Introduction

Toyota’s 1MZ-FE was a 3.0-litre petrol engine with a 60-degree ‘V’ angle. With its aluminium alloy cylinder block, the 1MZ-FE engine had a service weight of 151 kg and replaced Toyota’s 3VZ-FE engine. The 1MZ-FE was a non-interference engine.

In Australia, the 1MZ-FE engine was first introduced in the Lexus XV20 ES 300 and followed in the XV20 Camry and XV20 Vienta. For the Lexus XV30 ES 300, the 1MZ-FE was fitted with the Toyota’s ‘Variable Valve Timing – intelligence’ which provided variable inlet cam timing – this was the only 1MZ-FE engine to be so equipped in Australia.

1MZ-FE block

The 1MZ-FE engine had a deep-skirt, aluminium alloy cylinder block with six bolt main bearing caps. The 2995 cc 1MZ-FE had 87.5 mm bores – with a bore pitch of 105.5 mm – and an 83.0 mm stroke. Within the bores, the 1MZ-FE had press-fitted cast-iron cylinder liners. Furthermore, the cylinder banks had an offset 36.6 mm.

The cylinder block contained a water jacket through which coolant was pumped to cool the cylinders.

Crankshaft, connecting rods and pistons

The 1MZ-FE engine had a forged crankshaft with four main journals, nine semi-balance weights and roll-finished pins and journals. Crankshaft bearing caps were fastened using four plastic-region tightening bolts for each journal.

Attached to the crankshaft were sintered and forged connecting rods. Like the crankshaft, the connecting rods had plastic region tightening bolts.

The 1MZ-FE engine had aluminium alloy pistons with full-floating type piston pins which had snap rings fitted on both ends of the pins. Depending on its application, the piston skirt had a resin coating, molybdenum coating or Teflon coating. While the No.1 compression ring was made of steel, the No.2 compression ring was made of cast iron.

Cylinder head and camshafts

The 1MZ-FE engine had an aluminium alloy cylinder head and a carbon graphite-type cylinder head gasket. Within the cylinder head, the 1MZ-FE engine had cast iron alloy crankshafts. The exhaust camshafts were driven by a timing belt, while the intake camshafts were driven through gears on the exhaust camshafts. The scissor gear mechanism for the exhaust camshaft was used to control backlash and suppress gear noise. The camshaft journal was supported at five places between the valve lifters on each cylinder and on the front end of the cylinder head.

Acoustic Control Induction System (ACIS)

Certain applications of the 1MZ-FE featured an Acoustic Control Induction System (ACIS) which varied the length of the intake pipe to harness the effect of inlet pulsations to improve engine performance. ACIS consisted of:

• A bulkhead to divide the intake manifold into stages; and,
• An intake air control valve in the bulkhead which opened and closed to vary the effective length of the intake manifold according to engine speed and throttle valve opening angle.

The XV20 ES 300, XX10 Avalon and XV30 Camry had a two-stage ACIS, the XV30 ES 300 had a three-stage system.

Valves and non-VVT-i 1MZ-FE

The 1MZ-FE engine had four valves per cylinder with an included valve angle of 22.5 degrees (i.e. the angle between the intake and exhaust valves). The intake and exhaust valves were fitted with irregular pitch springs that were made of special valve spring carbon steel that was capable of following the cam profile at all engine speeds. Adjustment of valve clearance was done by means of an outer shim type system in which valve adjusting shims were located above the valve lifters – this permitted replacement of the shims without removal of the camshafts

The 1MZ-FE engine had 34.0 mm diameter intake valves and 27.3 mm diameter exhaust valves; valve stem diameter was 5.5 mm. Furthermore, intake valve lift was 7.85 mm and exhaust valve lift was 7.60 mm.

Non-VVT-i 1MZ-FE

For engines without Toyota’s ‘Variable Valve Timing – intelligence’ (VVT-i), the 1MZ-FE engine had valve overlap of 6 degrees, intake duration of 228 degrees and exhaust duration of 228 degrees.

VVT-i 1MZ-FE

For the XV30 ES 300, the 1MZ-FE engine had ‘Variable Valve Timing – intelligence’ which could vary inlet valve timing to provide greater torque at low engine speeds and power at high engine speeds. With VVTi, the 1MZ-FE engine had valve overlap of -2 to 58 degrees, intake duration of 236 degrees and exhaust duration of 236 degrees.

• A housing driven from the exhaust camshaft; and,
• A vane coupled with the intake camshaft.

In this system, oil pressure sent from the advance or retard side path at the intake camshaft caused rotation in the VVT-i controller vane circumferential direction to vary intake valve timing. Inlet camshaft timing was varied according to engine speed, throttle position, accelerator pedal angle, engine coolant temperature, intake air volume and intake air temperature.

When the engine was stopped, the intake camshaft would be in its most retarded state because of the external force of the valve springs. At this time, a lock pin fixed the housing and the vane in the VVT-i controller. When the engine started, the lock pin was released by the hydraulic pressure.

Injection and ignition

The 1MZ-FE engine had sequential multi-point fuel injection with a hot-wire air-flow meter to measure intake air density.

The 1MZ-FE engine had Toyota’s ‘Direct Ignition System’ which consisted of six ignition coils and each coil fitted over a spark plug. The spark plug was located in the centre of the combustion chamber.

The 1MZ-FE engine had a compression ratio of 10.5:1 and a firing order of 1-2-3-4-5-6.

Exhaust

The 1MZ-FE engine had stainless steel exhaust manifolds. For 1MZ-FE engines without VVT-i, an exhaust gas recirculation (EGR) system EGR system: recirculated a portion of the exhaust gases through the intake to reduce the nitrous oxides in the exhaust gases.

For the Lexus XV30 ES 300, the main muffler included a variable back-pressure valve. The exhaust valve opened steplessly according to back-pressure, remaining closed at low engine speeds to reduce noise and opening at higher engine speeds for improved performance.

Introduction

First introduced in 1993, Toyota’s 1KZ-TE was a 3.0-litre turbo-diesel four-cylinder engine. Key features of the 1KZ-TE included its alloy cast iron block, aluminium alloy cylinder head, single overhead camshaft, two valves per cylinder, drive-by-wire electronic throttle control and indirect injection. Furthermore, the 1KZ-TE engine had a 4400 rpm redline.

For Australia, the 1KZ-TE engine was first introduced in the 1997 Toyota Mk.6 Hilux. For the 90-Series and 120-Series LandCruiser Prado, in which the 1KZ-TE produced 96 kW, the engine was fitted with an air-to-air intercooler.

1KZ-TE block

The 1KZ-TE engine had a deep-skirt, externally ribbed, linerless cylinder block that was made from wear-resistant alloy and cast iron. The 1KZ-TE engine had 96.0 mm bores and a 103.0 mm stroke for a capacity of 2982 cc. Furthermore, the cylinder bores were ‘plateau honed’ for more efficient piston ring sealing.

Crankshaft, connecting rods and pistons

The 1KZ-TE engine had a fully balanced steel crankshaft that had five journals and operated on aluminium alloy bearings.

The connecting rods were made from lightweight carbon steel and each rod had an internal oil passage which supplied an oil gallery in the piston. The small-end connecting rod bearings were tapered to reduce mass, while the big-ends had plastic region tightening bolts to maximise clamping force

The pistons were made from aluminium alloy and a FRM (fibre reinforced metal) top ring groove to improve wear resistance.

Balance shafts

The 1KZ-TE engine had twin counter-rotating balance shafts within the crankcase to cancel the secondary inertia forces that were inherent in an in-line four-cylinder engine. Since each piston reached its maximum speed – both rising and falling – at a point just above the centre of the stroke, the upward inertial force of the two rising pistons was greater than the downward inertial force of the two falling pistons. To offset this, the twin gear-driven balance shafts counter-rotated at twice the speed of the crankshaft.

Cylinder head

The 1KZ-TE engine had an aluminium alloy cylinder head with a cross-flow configuration. The cylinder head was mounted on a steel laminate type head gasket and had plastic region tightening bolts to maximise clamping force. The cylinder head cover made of resin for its lightweight and noise absorption properties. Inside the cylinder head cover, a baffle plate and camshaft cover reduced engine oil consumption by reducing gas blow-by.

Turbocharger and intercooler

The 1KZ-TE engine had a water-cooled Toyota CT12B turbocharger. For the 96 kW output 1KZ-TE engines, an air-to-air intercooler was used; its dimensions were 320 mm by 230 mm by 65 mm.

Camshafts and valves

The 1KZ-TE engine had a single overhead camshaft (SOHC) that acted directly on the valves. The camshaft had a ‘gear and belt drive’ in that it was driven by timing gears to the injection pump gear, then a toothed rubber belt (which had an automatic tensioner and a belt idler).

The 1KZ-TE engine two valves per cylinder: one intake and one exhaust. As per the table below, the 1KZ-TE had 9 degrees of overlap, intake duration of 218 degrees and exhaust duration of 236 degrees.

Injection and combustion

The 1KZ-TE engine had electronically controlled, indirect fuel injection via fuel injection nozzles that had a double-cut needle. Fuel was supplied to the injectors via a Denso ‘Generation 3’ (ECD-V3-Rom-D) vane-type fuel pump which featured a spill control valve, timing control valve, fuel temperature sensor, engine speed sensor and correction PROM (Programmable Read Only Memory).

The 1KZ-TE engine had swirl type combustion chambers with ceramic-tipped glow plugs. Furthermore, the 1KZ-TE engine had a compression ratio of 21.2:1; the firing order was 1-3-4-2.

2003: 1KZ-TE upgraded for 120-Series LandCruiser Prado

For the 120-Series LandCruiser Prado, the 1KZ-TE was improved with the introduction of a lighter aluminium sump and electronic throttle control; an intercooler protector was also fitted for durability.

1KZ-TE Problems

1KZ-TE: Overheating

Overheating of the 1KZ-TE engine requires urgent attention since it can cause the cylinder head to crack. Overheating may be caused by:

• Failure of the viscous fan hub – this is generally noticed by temperatures rising when ascending hills or during stop/start traffic on hot days;
• Blockage of the radiator;
• Seizure of the wastegate actuator resulting in overboost;
• A hole in the heater hose; and,
• Too much load on the cooling system – a worn torque converter may contribute to this.

To improve the cooling system, common modifications for the LandCruiser Prado upgrading the radiator and fitting larger exhaust systems.

1KZ-TE: Cracked cylinder head

As a result of overheating, the 1KZ-TE is susceptible to cracked cylinder heads. Symptoms of a cracked cylinder head include:

• Small bubbles in coolant system, pushing coolant into the overflow bottle;
• Consumption and discolouration of coolant;
• Rapid overheating;
• Rough running; and,
• A loss of power.

If the cylinder head has cracked, the turbocharger is susceptible to overheating – this may cause excessive movement of the shaft and allow the blades to hit the housing. It is recommended that the cylinder head be replaced with a genuine Toyota head since there have been reports of casting faults in non-genuine products.

Please note that pressure testing the cylinder head does not always reveal a problem.

Introduction

The 1LR-GUE was a 4.8-litre V10 petrol engine that powered the Lexus LFA. Co-developed with Yamaha, the 1LR-GUE produced peak outputs of 412 kW at 8700 rpm and 480 Nm at 7000 rpm. Furthermore, maximum engine speed was 9000 rpm and 90 per cent of peak torque was available from 3700 rpm to 9000 rpm. The 1LR-GUE engine could rev from idle to 9000 rpm in 0.6 seconds, such that a digital LCD tachometer was used to match the engine’s ability to vary revolutions.

The 1LR-GUE engine also featured dry sump lubrication for lubrication capable of withstanding sustained high-speed cornering in excess of 2g.

1LR-GUE block and internals

The 1LR-GUE had an aluminium alloy block with 88.0 mm bores and a 79.0 mm stroke for a capacity of 4805 cc. The cylinder banks had a 72 degree ‘V’ angle for balancing the primary and secondary movement of the internals, and to circumvent the need for a split-journal crankshaft.

The 1LR-GUE engine had forged titanium alloy connecting rods, which were 40 per cent lighter than equivalent iron components, and forged aluminium pistons.

Cylinder head

The 1LR-GUE engine had an aluminium alloy cylinder head with double overhead camshafts and dual ‘Variable Valve Timing – intelligence’ (VVT-i). Furthermore, the 1LR-GUE engine had a magnesium alloy cylinder head cover.

Valves

The 1LR-GUE engine had four solid titanium valves per cylinder: two intake and two exhaust. The valves were actuated by solid rocker arms which were produced from high-strength tool steel and had a narrow profile for mass reduction. To reduce friction, the rocker arms had a diamond-like carbon/silicon coating.

Significantly, the valvetrain for the 1LR-GUE engine was estimated to have around half the inertia mass of a conventional high-performance engine that used steel valves and bucket type valve lifters.

Intake and throttle

The 1LR-GUE engine had a dual intake system that could switch from a primary inlet port at low to medium engine speeds to dual ports at higher speeds to enhance breathing efficiency.

Each cylinder had an independent, electronically controlled throttle body and throttle response was optimised by adopting ‘prioritised logic functionality’, which estimated air volume based on throttle pedal angle and enabled the appropriate injection volume to be calculated faster than a conventional system.

Injection and ignition

The 1LR-GUE engine had electronic fuel injection and twelve-hole injectors. For ignition, the 1LR-GUE had PK22HTBR-L8 Denso spark plugs, while the compression ratio was 12.0:1.

Exhaust and emissions

The 1LR-GUE engine had separate, equal-length exhaust manifold runners. Harmonic management used at the titanium dual stage rear silencer which incorporated a valve-actuated structure to vary exhaust sound. At engine speeds beyond 3000 rpm, all sound-deadening chambers were bypassed.

To reduce emissions, the 1LR-GUE engine had an air injection system which included an air pump that supplied fresh air into the exhaust after cold-engine start and early activating catalytic converters.

Introduction

Toyota’s 1KD-FTV was a 3.0-litre four-cylinder turbo diesel engine. A member of Toyota’s ‘KD’ engine family, which included the related 2KD-FTV, key features of the 1KD-FTV included its:

• Cast iron block;
• Aluminium alloy cylinder head;
• Variable nozzle vane type turbocharger;
• Intercooler;
• Double overhead camshafts;
• Four valves per cylinder; and,
• Compression ratio of 17.9:1.

In Australia, the 1KD-FTV engine was first introduced in the Toyota Mk.7 Hilux in April 2005, before following in the 120-Series LandCruiser Prado and Mk.5 HiAce in 2006; the full range is given in the table below. The 1KD-FTV engine is being replaced by the 1GD-FTV and 2GD-FTV engines.

1KD-FTV block

The 1KD-FTV engine had a deep-skirt cast iron cylinder block with 96.0 mm bores and a 103.0 mm stroke for a capacity of 2982 cc. The block had a reinforcing rib to reduce engine vibrations, while the cylinder bores were liner-less.

Balance shafts

Unlike the 2KD-FTV engine, the 1KD-FTV engine had two counter-rotating balance shafts that were driven by the crankshaft timing gear. The purpose of the balance shafts was to counteract the secondary inertia forces inherent in an in-line four-cylinder engine. Since each piston reached its maximum speed – both rising and falling – at a point just above the centre of the stroke, the upward inertial force of the two rising pistons was greater than the downward inertial force of the two falling pistons. To oppose this, the balance shafts rotated at twice the speed of the crankshaft in opposite directions to one another.

Crankshaft, connecting rods and pistons

The crankshaft for the 1KD-FTV engine had eight balance weights and five journals, while the pin and journal fillets were roll-finished. The crankshaft bearings were made from aluminium alloy and had micro-grooved lining surfaces to optimise oil clearance for better cold-engine cranking performance and reduced engine vibrations; the upper main bearing had an oil groove around its circumferences. To reduce noise, vibration and harshness (NVH), the crankshaft pulley had a torsional rubber damper.

The high-strength connecting rods had aluminium bearings and plastic region tightening bolts. Furthermore, knock pins used at the mating surfaces of the bearing caps of the connecting rod to minimise shifting of the bearing caps during assembly.

The 1KD-FTV engine had aluminium alloy pistons with resin-coated skirts. Other features of the 1KD-FTV pistons included:

• A Sintered Iron Reinforced Material (SIRM) ring carrier in the top ring groove of the piston; and,
• A Physical Vapor Deposition (PVD) coating for the surface of the no.1 compression ring.

For cooling and lubrication, oil jets at the bottom of the cylinder block sprayed oil into the internal cooling channels of the pistons; these oil jets had a check valve to prevent oil supply when oil pressure was low.

Cylinder head

The 1KD-FTV engine had an aluminium alloy cylinder head which used plastic region tightening bolts. The cylinder head was mounted on a steel-laminate type head gasket, while a shim was used around the cylinder bores to increase the area of the sealing surface.

To reduce mass and noise, the 1KD-FTV engine had a plastic cylinder head cover. Inside the cylinder head cover, there was a baffle plate to reduce the consumption of engine oil through blow-by gas.

Turbocharger and intercooler

The 1KD-FTV engine had a variable nozzle vane type turbocharger which included an impeller, turbine, nozzle vane, unison ring, DC motor and nozzle vane position sensor. Exhaust gas from the exhaust manifold passed through the nozzle vane inside the turbocharger housing and then flowed to the exhaust pipe through the turbine wheel. The speed of the turbine wheel (and hence turbocharging pressure) varied according to the opening of the nozzle valve. For example,

• At idle, exhaust gas flow was relatively low and the nozzle vane was fully closed. However, since there was a slight clearance between the vanes, exhaust gas would flow through this clearance to the exhaust pipe (i.e. no bypass);
• At low engine loads or speeds, the nozzle vane actuator would retract the actuator linkage which was connected to a unison ring – this would cause the drive arms on the unison ring to change nozzle vane angle toward the closed position. As a result, the flow velocity of the exhaust gas to the turbocharger increased for greater torque output; and,
• At high engine loads or speeds, the actuator would pull down the actuator linkage and the drive arms would change nozzle vane angle toward the open position – this would maintain the specified turbocharging pressure and reduce exhaust gas back pressure, improving power output and fuel consumption.

Inside the bearing housing of the turbocharger, a water jacket was used to improve cooling.

The IKD-FTV engine had an air-cooled intercooler which was located on top of the engine and intake air to increase its density and increase engine performance. The intercooler and the inlet tank were made of aluminium, while the outlet tank was made of plastic for mass reduction.

Camshafts

The 1KD-FTV engine had double overhead camshafts with a belt and gear drive. As such, the intake camshaft was driven by a replaceable rubber timing belt, while the exhaust camshaft was driven via a gear on the intake camshaft. To reduce noise, the gear had small diameter, flat teeth gears.

To increase abrasion resistance, the noses of each cam lobe were chill-treated.

Valves

The 1KD-FTV engine had four valves per cylinder – two intake and two exhaust – that were actuated directly by shim-less valve lifters that provided a large cam contact surface. Adjustment of valve clearance required the valve lifters to be replaced.

The 1KD-FTV engine had valve overlap of 2 degrees, intake duration of 219 degrees and exhaust duration of 225 degrees.

Intake and throttle

The 1KD-FTV engine had two intake ports for each cylinder which had different shapes to increase swirl in the combustion chamber. Unlike the standard 2KD-FTV engine, all 1KD-FTV engines had vacuum-actuated swirl control valves in one of the two intake ports for each cylinder. The swirl control valves consisted of a stainless steel shaft and an actuator which was integrated in the valve. At low engine speeds, the swirl control valve would close to increase swirl; for cold starts and high engine speeds, the valve would be open.

The intake shutter valve (throttle valve) was fitted with a rotary solenoid type torque motor, while non-contact sensors were used for both the intake shutter valve and accelerator pedal position sensors.

Common-rail injection (D-4D)

The 1KD-FTV engine had common-rail injection (Toyota’s ‘Direct Injection 4-Stroke Common Rail Diesel Engine’, or D-4D). The function of the common-rail was to store fuel that had been pressurised by the supply pump. The common-rail contained a main hole and five branch holes that intersect the main hole; each branch hole functions as an orifice that dampens the fluctuation of the fuel pressure. Furthermore, the common-rail had a fuel pressure sensor and a pressure limiter that mechanically relieved pressure if it rose abnormally (200 MPa).

The injectors consisted of a nozzle needle, piston and solenoid valve. When an electric current was applied to the solenoid coil, the solenoid valve would retract. The orifice of the control chamber would then open to allow fuel to flow out, causing fuel pressure in the control chamber to drop. Simultaneously, fuel would flow from the orifice to the bottom of the piston and the piston would rise. As a result, the piston would raise the nozzle needle to inject fuel.

For the 1KD-FTV engine, common-rail pressure ranged from 30 to 160 MPa. The 1KD-FTV engine used eight-hole type injectors where the holes measured 0.14 mm. Furthermore, each injector was located in the centre of the combustion chamber.

The ECU calculated target injection pressure based on signals from the acceleration pedal position sensor and crankshaft position sensor. The ECU controlled the Suction Control Valve (SCV) opening to regulate pumping volume so that the pressure detected by the fuel pressure sensor matched the target injection pressure.

The 1KD-FTV engine could perform ‘pilot injection’ which consisted of a series of small injection phases prior to the main injection phase. Pilot injection was used to reduce:

• Ignition delay at the main injection;
• Noise and vibrations; and,
• Emissions by preventing sudden increases in combustion pressure.

The electronic injection system determined the volume, timing and count interval between pilot injections and the main injection.

For ease of starting, the glow plug was placed between the intake ports of each cylinder. Firing order for the 1KD-FTV engine was 1-3-4-2.

Exhaust and emissions

The 1KD-FTV engine used a ball joint to connect the exhaust manifold to the front exhaust pipe and an oxidation catalytic converter was used to clean exhaust gas particulates (HC and CO).

For models complying with Euro III and beyond emissions standards, the 1KD-FTV engine used cooled exhaust gas recirculation (EGR) to reduce recirculate a small amount of inert exhaust gas into the intake manifold, thereby reducing peak temperatures in the combustion chamber and NOx formation. For the 1KD-FTV engine, a vacuum port for a Vacuum Switching Valve (VSV) was used to improve valve closure response.

1KD-FTV problems

1KD-FTV engine: injector seal failure (2005-07)

Initially, the 1KD-FTV engine had copper seats at the base of the common rail injector to provide a seal against the combustion chamber.These seats, however, can fail and cause the following problems:

• Blow-by gases enter the tappet cover and mix with the engine oil – this bakes and carbonises the engine oil;
• Blow-by gases block the oil sump pick-up;
• The engine can be starved of oil;
• The lack of lubrication cause excessive friction and heat, causing the bottom end bearings to melt and engine failure.

Symptoms of a failed common rail injector seal include:

• White smoke and a rattling noise after a cold start; and,
• A blocked oil sump pick-up.

AustralianCar.Reviews understands that new diamond-like coating (DLC) seats were introduced for the 1KD-FTV engine from August 2007. AustralianCar.Reviews recommends that owners of vehicles with the 1KD-FTV engine which have copper injector seats have them replaced with the updated injectors and the oil sump pick-up cleaned if there is evidence of the copper injector seats allowing blow-by gases to pass. At each service, the oil sump pick-up should be inspected and, if required, cleaned by removing the oil sump covers, taking out the screen and spraying it with a carbon cleaner or degreaser.

For further information, please see pradopoint.com and What Causes the Hilux and Prado Clogged Oil Sump Pickup?

1KD-FTV engine: injector failure

It is not uncommon for the injectors in the 1KD-FTV engine to fail around 120,000 to 140,000 kilometres, though they may fail as early as 75,000 kilometres or last 250,000 kilometres. Symptoms of a failing injector include:

• A loud ‘knock’ noise that is audible when the windows are down, particularly when the engine is cold;
• Poor fuel economy;
• An erratic or rough idle; and,
• Rough running, particularly under load at low engine speeds.

The shorter lifespan of these injectors is attributable to the high fuel pressure (from 30 to 160 MPa), multiple injections per combustion stroke, small tolerances and fuel quality. As a preventative measure, it is recommended that the injectors be replaced every 100,000 kilometres. At each service, it is recommended that a diagnostic test be conducted to measure feedback volumes or total volumes for the injectors to see if they are working properly.

1KD-FTV engine: cracked pistons

For 2006-14 Toyota vehicles with 3.0-litre 1KD-FTV engines that comply with Euro IV emissions standards, the pistons are susceptible to cracking. While the size of the cracks varies, they can amount to a localised rupture. In affected vehicles, piston cracking is most common between 100,000 km and 150,000 km. Issued in September 2014 by Toyota, Technical Service Bulletin EG-008T-0112 acknowledged the problem of cracked pistons for the Euro IV 1KD-FTV engine.

Symptoms of a cracked piston include:

• A sudden, strong knocking noise from the engine;
• Black smoke from the exhaust;
• A loss of power;
• The engine ‘running rough’ (i.e. on 3 cylinders); and,
• Excessive crankcase pressure.

The pre-Euro IV 1KD-FTV engines did not experience this problem because the piston had a metal fibrous structure fused into the piston crown. The piston design, however, was changed for the Euro IV 1KD-FTV engine.

To reduce the risk of cracked pistons in a Euro IV 1KD-FTV engine, it is recommended that:

• The engine not be subjected to chip tuning;
• The vehicle not be driven for under load for extended periods; and,
• That the fuel injectors are serviced every 100,000 kilometres.

While these measures will reduce the likelihood of failure, they do not rectify the design fault of the pistons.

According to the technical bulletin, two production changes – ‘improved injectors to prevent wrong combustion’ and more robust pistons – were implemented in 2014 –

• For the 150-Series LandCruiser Prado (KDJ150/KDJ155), these production changes were implemented in January 2014 from engine no. 2361817; and,
• For the Mk.7 Hilux (KUN26), these production changes were implemented in July 2014 from engine no. A477120.

Despite these changes, however, cracked pistons have been reported in revised vehicles (although the failure rate is lower).

Toyota’s 1HZ was a 4.2-litre diesel engine that was offered in Toyota LandCruiser vehicles . Key features of the 1HZ engine included its cast iron cylinder block and head, single overhead camshaft, two valves per cylinder and indirect injection. Although there are aftermarket examples of turbocharged 1HZ engines, Toyota did not offer a turbocharged 1HZ engine.

In 1998, the 1HZ engine was upgraded for the 105-Series LandCruiser – these changes are included in the description below.

1HZ block

The 4164 cc cast iron cylinder block for the 1HZ had 94.0 mm bores and a 100.00 mm stroke. The cylinder block contained a water jacket through which coolant was pumped to cool the cylinders, while the oil pan was bolted onto the bottom of the crankshaft bearing cap.

For the post-1998 1HZ engine, the rigidity of the cylinder block was improved to reduce noise and vibration.

Crankshaft

The crankshaft for the 1HZ engine had twelve balancing weights and was supported by seven aluminium alloy bearings. The crankshaft bearing cap had ladder frame construction and was incorporated into the crankcase, while plastic region tightening bolts were used for both the crankshaft bearing cap bolts and connecting rod cap bolts. Furthermore, the crankshaft had built-in oil holes to supply oil to the connecting rods, bearings and other components.

For the post-1998 1HZ engine, a more rigid crankshaft was adopted and the crankshaft bearings were machine-bored for greater reliability.

Pistons

The 1HZ engine had aluminium alloy pistons with full-floating type piston pins for which snap rings were fitted to both ends of the pin to prevent the pin from slipping out. Of the piston rings,

• The no.1 compression ring was made of steel
• The no.2 compression ring of cast ring; and,
• The oil ring was made of steel.

The outer diameter of each piston ring was slightly larger than the diameter of the piston and the flexibility of the rings enabled them to hug the cylinder walls when they were mounted on the piston. The no.1 and no.2 compression rings operated to prevent the leakage of gas from the cylinder, while the oil ring scraped oil off the cylinder walls to prevent it from entering the combustion chamber.

From 1998, the top piston ring groove was treated with MMC (Metal Matrix Composites) – previously FRM (Fibre Reinforced Metal) – to increase wear resistance. Furthermore,

• The shape of the piston skirt was optimised and the steel strut discontinued; and,
• The shape of the combustion chamber at the top of the piston was changed.

Cylinder head

The 1HZ engine had a cast iron cylinder head with a cross-flow configuration and swirl-type combustion chamber; plastic region tightening bolts were used for the cylinder head bolts. The camshaft journal part of the cylinder head was made of cast iron and had aluminium alloy camshaft caps.

Camshaft

The 1HZ engine had a single overhead camshaft (SOHC) that was driven by the timing belt. While the original 1HZ engine had an automatic, wear-reducing timing belt tensioner, this was changed to a hydraulic type for the post-1998 1HZ engine. For the post-1998 1HZ engine, a cover with integrated foam rubber was adopted for the timing belt cover gasket for easier servicing.

The camshaft journal was supported at seven locations; lubrication of the camshaft journal and cam occurred via the oil port of the no.7 camshaft journal. With the exception of the no.1 journal, the camshaft journal had no bearings.

Valves

The 1HZ engine had two valves per cylinder – one intake and one exhaust – that were fitted with irregular pitch springs. The valves were actuated directly and valve clearance was adjustment occurred via an outer shim type system in which valve adjusting shims were located above the valve lifters – this enabled the shims to be replaced without having to remove the camshaft.

Valve timing for the 1HZ engine is given in the table below; the 1HZ engine had valve overlap of 13 degrees, intake duration of 224 degrees and exhaust duration of 236 degrees.

Injection

The 1HZ engine had indirect injection. For the post-1998 1HZ engine, the orifice of the injection nozzle was increased from 1.0 mm to 1.2 mm and its shape was changed to optimise the injection rate. Furthermore, the injection pump adopted Fuel Cut Valve Control (FCVC) and an engine immobiliser was introduced. Upon receiving a signal from the transponder key computer, the FCVC turned off the fuel cut valve to prohibit the engine from starting if an invalid ignition key was used to start the engine.

For the post-1998 1HZ engine, new metal glow plugs were introduced which had a temperature control function in the plug itself; the glow plug resistor and sub-relay were also discontinued.

For the post-1998 1HZ engine, the shape of the combustion chamber and the piston were changed to reduce exhaust emissions. While the original 1HZ engine had a compression ratio of 22.7:1, this was lowered to 22.4:1 for the post-1998 1HZ engine.

Exhaust

The 1HZ engine had dual-type exhaust manifolds.

2002: 1HZ update

In October 2002, the 1HZ engine for the HZJ105 LandCruiser was upgraded with: :

• An exhaust gas recirculation system; and,
• A timing control valve for the fuel injection pump to reduce nitrogen emissions.

Introduction

The 1FZ-FE was a 4.5-litre inline six-cylinder petrol engine that replaced Toyota’s 3F-E engine. The 1FZ-FE engine had a cast iron block with 100.0 mm bores and a 95.0 mm stroke for a capacity of 4477 cc.

The 1FZ-FE engine had a cast iron cylinder head and double overhead camshafts. The intake camshaft was driven by a single roller chain, while the exhaust camshaft was driven by a scissor gear off the intake camshaft. The 1FZ-FE engine had four valves per cylinder – in a cross-flow layout – that were actuated by outer pad type valve lifters with adjusting shims. As per the table below, the 1FZ-FE engine had valve overlap of 10 degrees, intake duration of 225 degrees and exhaust duration of 225 degrees.

Introduction

Toyota’s 1GR-FE was a 4.0-litre V6 petrol engine that was first available in Australia in the 2003 Toyota 120-Series LandCruiser Prado, but subsequently offered in the Toyota Mk.7 Hilux. For these vehicles, key features for the 1GR-FE engine included its aluminium alloy cylinder block and head, variable intake valve timing (VVT-i), Acoustic Control Induction System (ACIS) and compression ratio of 10.0:1.

For the 150-Series LandCruiser Prado and FJ Cruiser, however, an upgraded 1GR-FE engine was used which had modified internals, variable intake and exhaust valve timing (‘dual VVT-i), omitted ACIS and had a compression ratio of 10.4:1.

This article will describe attributes of the original 1GR-FE engine and include details of the differences with the upgraded, ‘dual VVT-i 1GR-FE’ engine in turn.

1GR-FE Block

With its die-cast aluminium alloy cylinder block, the cylinder banks of the 1GR-FE engine had a 60-degree ‘V’ angle. The 1GR-FE engine had 94.0 mm bores and a 95.0 mm stroke for a capacity of 3956 cc; bore pitch was 105.5 (i.e. the distance between the centre of adjacent bores), while cylinder bank offset was 36.6 mm. Between the cylinder bores, passages existed for coolant flow.

The 1GR-FE engine had ‘spiny type’ cast-iron cylinder liners. The casting exteriors of these liners had irregular surfaces to enhance the adhesion between the liners and the aluminium cylinder block – this improved heat dissipation and reduced heat deformation of the cylinder bores.

For the dual VVT-i 1GR-FE engine, the surface cross-hatching of the cylinder liner was optimised to improve oil retention performance, thereby reducing friction. Furthermore, cylinder block water jacket spacers were added to the water jacket. The cylinder block water jacket spacers prevented water flow in the middle and below the water jacket, and drew coolant above the cylinder bore for uniform temperature distribution. As a result, the viscosity of the engine oil that acted as a lubricant between the bore walls and the pistons could be lowered, thus reducing friction.

Crankshaft, connecting rods and pistons

For the VVT-i 1GR-FE engine, the forged steel crankshaft had four journals and nine balance weights. The six-bolt main crankshaft bearings were made of aluminium alloy and, like the connecting rod bearings, the lining surfaces were micro-grooved for an optimal amount of oil clearance – this improved cold-engine cranking performance and reduced engine vibration. Furthermore, all pin and journal fillets were roll-finished. The crankshaft bearing caps were tightened using four (4) plastic region tightening bolts for each journal.

For the dual VVT-i 1GR-FE engine, a five balance weight crankshaft was introduced (as per the 2GR-FE); the locations of the balance weights were optimised to reduce vibration and noise.

The 1GR-FE engine had forged connecting rods which used aluminium bearings; for an optimal amount of oil clearance, the lining surface of the connecting rod bearing was micro-grooved. The connecting rods and caps were made of high-strength steel and nutless-type plastic region tightening bolts were used to reduce mass. Furthermore, knock pins were used at the mating surfaces of the bearing caps to minimise movement during assembly.

The 1GR-FE engine had aluminium alloy pistons which had a ‘taper squish’ shape for the piston head. Furthermore, the groove of the top piston ring was coated with anodic oxide to improve wear resistance and rust resistance, while the piston skirt was coated with resin to reduce friction. Oil-cooling jets under the pistons acted to reduce piston temperatures.

For the higher compression ratio of the dual VVT-i 1GR-FE engine (10.4:1 versus 10.0:1), the shape of the pistons was optimised. To reduce weight, cast holes were added on the bottom of the piston head near the pin bosses. The outer surfaces of the second compression ring were also plated with chrome to be compatible with petrol/ethanol blends.

Cylinder head

The 1GR-FE engine had an aluminium alloy cylinder head with steel laminate-type head gaskets. To increase the sealing surface for better durability, a shim was added around the cylinder bore. For the dual VVT-i 1GR-FE engine, the structure of the cylinder head was simplified by separating the camshaft housing (cam journal portion) from the cylinder head.

The cylinder head bolts were positioned below the camshaft journal in the front of the right bank, and the holes for placing the bolts were above the camshaft journal. Furthermore, the 1GR-FE engine had an aluminium cylinder head cover.

CCamshafts

The 1GR-FE engine had double overhead camshafts that were made of cast iron alloy. Both the primary and secondary timing chains used pitch roller chains with a pitch of 9.525 mm. The intake camshafts were driven by the crankshaft via the primary timing chain. The exhaust camshafts were driven by the intake camshaft of the respective bank via the secondary timing chain.

The primary timing chain used one chain tensioner (ratchet type with a non-return mechanism), and each of the secondary timing chains for the right and left banks used one chain tensioner. Both the primary and secondary chain tensioners used a spring and oil pressure to maintain proper chain tension at all times. Furthermore, the timing chains were lubricated by oil jets.

For the dual VVT-i 1GR-FE, the cam lobes had indented R profiles to increase valve lift when the valve began to open and as it finished closing.

Shimless type valve lifters/rocker arms

For valve actuation, the VVTi 1GR-FE had shimless type valve lifters. The dual VVTi 1GR-FE engine, however, had roller rocker arms with built-in needle bearings that reduced the friction that occurred between the camshafts and the roller rocker arms. The hydraulic lash adjuster – located at the fulcrum of the roller rocker arm – consisted primarily of a plunger, plunger spring, check ball and check ball spring. Through the use of oil pressure and spring force, the lash adjuster maintained a constant zero valve clearance.

VVT-i

For the 120-Series LandCruiser Prado andMk.7 Hilux, the variable inlet valve timing (VVT-i) a 50 degree range of adjustment (relative to crankshaft. Furthermore, the 1GR-FE engine had valve overlap of -6 degrees, intake duration of 232 degrees and exhaust duration of 236 degrees.

• An oil control valve (mounted on the cylinder head); and,
• Vane-type actuators on the ends of the intake camshafts.

The ECU also used signals from the camshaft position sensor and the crankshaft position sensor to detect actual valve timing, thus providing feedback control to achieve the target valve timing.

When the engine stopped, the intake side VVT-i controller was locked on the most retarded angle side by the lock pin, and the exhaust side VVT-i controller was locked on the most advanced angle side.

Dual VVT-i 1GR-FE

For the150-Series LandCruiser Prado andFJ Cruiser, the dual VVT-i system could vary inlet valve timing over a range of 40 degrees and exhaust camshaft timing over a range of 35 degrees (relative to crankshaft angle). Maximum valve overlap (the period when both exhaust and inlet valves were open) was 68 degrees for maximum power, while minimum overlap was -7 degrees for optimum economy.

Intake and ACIS

For the 1120-Series LandCruiser Prado andMk.7 Hilux VVT-i 1GR-FE engine, the intake air chamber was made of plastic and contained an intake air control valve for Toyota’s ‘Acoustic Control Induction System’ (ACIS). ACIS consisted of:

• A bulkhead to divide the intake manifold into two stages; and,
• An intake air control valve in the bulkhead which opened and closed to vary the effective length of the intake manifold according to engine speed and throttle valve opening angle.

When the engine was running at middle speed under high load, an actuator would close the intake air control valve to increase the effective length of the intake manifold and improve intake efficiency – at medium engine speeds – due to the effect of inlet pulsations. In any condition other than middle speed running under high loads, the intake air control valve was open to shorten the effective length of the intake manifold. The dual VVT-i engine, however, omitted ACIS.

The 1GR-FE had straight and upright Siamese-type intake ports to reduce the overall surface area to the intake port walls and prevent fuel from adhering onto the intake port walls (wall wetting).

The 1GR-FE engine had a linkless-type throttle body in which the throttle position sensor and the throttle control motor were integrated. Furthermore, Toyota’s ‘Electronic Throttle Control System – intelligent’ (ETCS-i) controlled the throttle valve in accordance with the amount of accelerator pedal effort and the condition of the engine.

Injection

The 1GR-FE engine had a hot-wire air flow meter to measure intake air mass and a sequential fuel injection system which included a twelve-hole injector for each cylinder. The 1GR-FE engine also had a planar-type air-fuel ratio sensor and oxygen sensor which, according to Toyota, warmed up three times faster than the conventional type to achieve increased mixture accuracy.

For the VVT-i 1GR-FE engine, fuel pressure was 284 kPa; for the dual VVT-i 1GR-FE engine, however, this was increased to 324 kPa for compatibility with ethanol blend fuels. For the dual VVT-i engine, fuel injector was repositioned so that it extended into the intake port; the distance between the injector nozzle end and intake valves was also shortened to reduce wall wetting.

The 1GR-FE used an ‘independent’ injection system in which fuel was injected once into each cylinder for each two revolutions of the crankshaft. Furthermore, there were two injections:

• A synchronous injection in which corrections based on the signals from the sensors were added to the basic injection timing so that injection always occurred at the same position; and,
• A non-synchronous injection in which injection was influenced by signals from sensors (regardless of the crankshaft angle). To protect the engine and improve fuel economy, the system could temporarily cut off fuel supply.

Ignition

The 1GR-FE engine had a coil-on-plug ignition system, Toyota’s ‘Direct Ignition System’ (DIS), in which the spark plug cap was integrated with the ignition coil. Ignition timing was determined by the ECU based on signals from various sensors; the ECU corrected ignition timing in response to engine knocking.

The 1GR-FE had long-reach spark plugs that were positioned in the centre of the combustion chamber. For the VVT-i 1GR-FE engine, the spark plugs were either Denso K20HR-U11 (nickel type) or NGK LFR6C-11 (nickel type). For the dual VVT-i 1GR-FE, the nickel type spark plugs were replaced by Denso SK20HR11 iridium-tipped spark plugs which had 200,000 km maintenance intervals. By adopting an iridium centre electrode, ignition performance was superior to that of platinum-tipped spark plugs and durability was increased.

The 1GR-FE engine had pentroof-type combustion chambers with a ‘taper squish’ shape to improve anti-knocking performance. The squish angle was shaped obliquely along the wall surface of the combustion chamber to improve airflow, promote swirl and accelerate flame travel.

For the VVT-i 1GR-FE engine, the compression ratio of 10.0:1; for the dual VVT-i 1GR-FE, it was 10.4:1. The firing order of the 1GR-FE engine was 1-2-3-4-5-6.

Exhaust

The stainless-steel exhaust manifold had an integrated three-way ceramic-type catalytic converter. The catalytic converter was an ultra thin-wall, high-cell density ceramic type. For the exhaust, a ball joint was used to join the exhaust front pipe and exhaust centre pipe to minimise vibration.

For the dual VVT-i 1GR-FE engine,

• The shape of the exhaust manifold was revised to optimise exhaust gas flow and reduce pressure loss;
• Volume and cell density of the three-way catalytic converter were optimised; and,
• The material of the exhaust pipe was changed to improve rust resistance.

Introduction

Toyota’s 1HD-FTE was a 4.2-litre inline six-cylinder turbo-diesel engine with cast iron construction, direct injection, a single overhead camshaft and four valves per cylinder. Manufactured at Toyota’s hermetically sealed Hekkinen engine plant near Nagoya, the 1HD-FTE was based on the 1HD-FT engine, but introduced an electronically-controlled injection pump and intercooler. For the Toyota 100-Series LandCruiser (HDJ100), the 1HD-FTE engine produced peak power and torque of 151 kW at 3400 rpm and 430 Nm at 1400-3200 rpm; its redline was 4000 rpm.

With its cast iron block and cylinder head, the 1HD-FTE engine had a service mass of 348 kg for models with manual transmissions and 341 kg for models with automatic transmissions.

1HD-FTE block

The 1HD-FTE engine had a cast iron block with 94.0 mm bores and a 100.0 mm stroke for a capacity of 4164 cc. For rigidity, the cylinder block had external ribbing.

Crankshaft, connecting rods and pistons

The 1HD-FTE engine had a forged crankshaft with seven forged journals and twelve balance weights. Furthermore, the 1HD-FTE engine had a ladder type crankshaft bearing cap, while the main bearings had machine-bored inner surfaces to provide minute circumferential crests and valleys in the bearing surface. To reduce noise and vibration, a torsional damper crankshaft pulley was used.

The connecting rods were made from carbon-steel and had tapered small ends to reduce mass. For the aluminium alloy pistons, the top ring groove was treated with Metal Matrix Composites (MMC) to improve wear resistance and a gas nitriding process was applied to the piston ring surface to improve durability and reduce piston ring tension.

CCylinder head

The 1HD-FTE engine had a cast iron cylinder head which was mounted on a three-layer steel laminate type head gasket. The gasket had bead construction at its cylinder bores, water holes and oil holes.

The 1HD-FTE engine had a resin cylinder head cover which included a blowby gas passage with a maze-like configuration to reduce consumption of engine oil through blowby gas. A secondary cylinder head cover – made of iron sheet and with foam rubber on the inside – sat atop the primary cylinder head. A vibration isolating rubber gasket was used to achieve a floating retaining construction.

Relative to the 1HD-FT, cooling performance was improved for the 1HD-FTE engine by enlarging the water jacket around the exhaust valves and injection nozzles.

Intake, turbocharger and intercooler

The 1HD-FTE engine had an aluminium intake manifold that was integrated with a large-capacity intake air chamber. To reduce noise, insulators were used where the intake manifold was mounted onto the cylinder head. For optimum breathing and swirl in the combustion chamber, the 1HD-FTE engine had a combination of helical and tangential inlet ports.

The intake manifold gasket was made of steel plates that were coated with foam rubber on both sides, then riveted to a stainless steel substrate. A composite gasket cinched with layered washers was used in areas that were tightened with bolts to achieve a floating retaining construction.

The 1HD-FTE was fitted with a CT20B (100-Series) or CT26 (80-Series) turbocharger. Furthermore, an air-cooled intercooler was used to lower intake air temperature and increase charge density.

Camshafts and valves

The 1HD-FTE engine had a hollow, single overhead camshaft (SOHC) that was made from carbon steel. The camshaft was driven by a belt and gears, while the timing gear train included a hydraulic auto tensioner. Furthermore, the timing gear train drove the oil pump, vacuum pump, steering gear pump, injection pump and camshaft.

The rocker arms were made of aluminium and used rollers to improve wear resistance; each rocker actuated a pair of valves. The rocker arm shaft – to which the rocker arms, nozzle clamps and camshaft bearing caps were attached – was mounted on the cylinder head via the camshaft bearing caps.

Compared to the 1HD-FT, the length of the exhaust valve was extended so that the valve in its fully closed state was positioned close to the piston to reduce the unnecessary amount of space in the combustion chamber – this improved combustion efficiency

For the 1HD-FTE engine, valve overlap was 24 degrees, intake duration was 216 degrees and exhaust duration 246 degrees (see table below).

Injection and ignition

For the 1HD-FTE engine, the fuel pump delivered fuel to the pump chamber at a pressure between 1.5 and 2.0 MPa. The 1HD-FTE engine then used a radial plunger type, electronically controlled injection pump and two-stage, direct injection nozzles which had valve covered orifices (VCOs). Compared to the 1HD-FT, the pre-lift of the injection nozzles was reduced for quieter operation. The injection nozzles were positioned perpendicularly over the centre of the cylinder bore

The ECU calculated the basic injection volume based on the throttle opening and engine speed, and the maximum injection volume for the engine condition. The two injection volumes were then compared and the lesser value selected. A correction value which was obtained via the correction resistors was added to that injection volume to determine the final injection volume.

The 1HD-FTE engine had a centralised, Toyota reflex-burn combustion chamber design. Furthermore, the compression ratio was 18.8:1 and the firing order 1-4-2-6-3-5.

Exhaust and EGR

The 1HD-FTE had a cast iron exhaust manifold that was mounted on a five-layer steel laminate type exhaust manifold gasket.

The exhaust pipe was made of stainless steel and the front exhaust pipe had an oxidation catalytic converter. Furthermore, a ball-joint was used for joining the turbocharger and the front exhaust pipe; a clamp type joint was used to join the centre exhaust pipe and tail pipe.

For the 1HD-FTE engine’s EGR system, the ECU controlled the vacuum regulating valve to recirculate an appropriate amount of exhaust gas to the combustion chamber – this slowed the combustion rate, lowered combustion temperature and reduced NOx emissions.

Introduction

Toyota’s 1AR-FE was a 2.7-litre inline four-cylinder petrol engine. For Australia, the 1AR-FE engine has only been offered in the Lexus AL10 RX 270. In international markets, however, it has powered the Toyota Venza, Highlander and Sienna.

Features of the 1AR-FE included its:

• Die-cast aluminium block and crankcase;
• Offset crankshaft;
• Double overhead camshafts with roller rocker arms;
• Dual VVT-i; and,
• 10.0:1 compression ratio.

1AR-FE block

The 1AR-FE had am open deck, midi-skirt cylinder block that was made from die-cast aluminium. With its 90.0 mm bores and a 105.0 mm stroke (7.0 mm greater than the related 2AR-FE), the 1AR-FE engine had a capacity of 2672 cc. With the cylinder bores, the 1AR-FE had ‘spiny-type’ cast-iron liners which were manufactured so that the casting exteriors of the liners had irregular surfaces for better adhesion between the liners and the cylinder block.

The 1AR-FE block also contained:

• Oil jets for cooling and lubricating the pistons and bores;
• Water passages between the cylinder bores so that coolant could flow and keep the temperature of the cylinder walls uniform; and,
• A shallow bottom water jacket used to reduce the volume of engine coolant for faster warm-up. The water jacket included a water jacket spacer to suppress water flow in the bottom of the water jackets and guide the coolant in the upper area of the water jacket for uniform temperature distribution. As a result, the viscosity of the engine oil that acted as a lubricant between the bore walls and the pistons was lowered.

Within the die-cast aluminium crankcase, the 1AR-FE contained:

• Two balance shafts to counteract the secondary inertial forces that were generated twice for each rotation of the crankshaft. The crankshaft had helical gear that was pressed in the no.3 counterweight that was used to drive the no.1 balance shaft, while the no.2 balance shaft was gear-driven from the no. 1 balance shaft. To cancel secondary inertial forces, the balance shafts rotated twice for each rotation of the crankshaft to generate inertial force in the opposite direction. To cancel the inertial force generated by the balance shaft itself, the balance shaft consisted of two shafts rotating in opposite directions;
• Blowby gas passages with an oil separator that would separate oil from the blowby gas to reduce oil degradation and consumption; and,
• Oil drain passages to prevent the crankshaft from mixing the engine oil (reducing rotational resistance).

Crankshaft, connecting rods and pistons

The 1AR-FE engine had a forged steel crankshaft that had eight balance weights and was supported by five main bearings. To reduce lateral forces to the cylinder wall, the crankshaft was offset to move the bore centre 10 mm towards the exhaust side (relative to the crankshaft centre). Other attributes of the crankshaft included:

• A micro-grooved lining surface for an optimal amount of oil clearance; and,
• Narrow crankshaft bearings with eccentric oil grooves to reduce the amount of oil leakage from the bearing.

The connecting rods and caps were made of micro-alloyed steel; to reduce mass, the connecting rods used plastic region tightening bolts. Like the crankshaft, the connecting rod bearings had micro-grooved lining surfaces and a narrow width to reduce friction.

The 1AR-FE engine had aluminium alloy pistons with a ‘taper squish’ shape head to improve combustion efficiency. To reduce frictional losses, the piston skirts were coated with resin and low tension piston rings were used. To improve wear resistance, the top compression ring had an ‘inside bevel’ shape and a Physical Vapor Deposition (PVD) coating was applied to its surface to improve wear resistance.

Cylinder head

The 1AR-FE engine had an aluminium cylinder head in which the camshaft housing (cam journal portion) was separated from the cylinder head. The cylinder head was affixed to the block with a triple-layer metal type cylinder head gasket the surface of which was coated with fluoro rubber.

The 1AR-FE engine had a magnesium alloy die-cast cylinder head cover which contained an oil delivery pipe for lubrication of the sliding parts of the roller rocker arm.

Camshafts and roller rockers

The intake and exhaust camshafts for the 1AR-FE engine were driven by a 9.525 mm roller chain. The timing chain was lubricated by an oil jet, while the chain tensioner – a ratchet type with a non-return mechanism – used a spring and oil pressure to maintain chain tension. The 1AR-FE engine had roller rocker arms with built-in needle bearings that reduced friction between the cams and the roller rocker arms (which actuated the valves down).

The 1AR-FE engine used hydraulic lash adjusters to maintain constant zero valve clearance through the use of oil pressure and spring force. The hydraulic lash adjuster was located at the fulcrum of the roller rocker arm and consisted of a plunger, plunger spring, check ball and check ball spring. The hydraulic lash adjuster was actuated by engine oil supplied via the cylinder head and the built-in spring. The oil pressure and the spring force that acted on the plunger pushed the roller rocker arm against the cam to adjust the valve clearance that was created during the opening and closing of the valve.

The cam profile had an indented R (radius) to increase valve lift when the valve began to open and finished closing.

Dual VVT-i

For the 1AR-FE engine, the ‘dual variable valve timing with intelligence’ (Toyota’s ‘Dual VVT-i) system controlled the intake and exhaust camshafts within a range of 50 degrees and 40 degrees respectively (relative to crankshaft angle).

Each VVT-i controller consisted of a housing that was driven by the timing chain and a vane that was coupled with the intake or exhaust camshaft. Both the intake and exhaust sides had four-blade vane-type actuators. The camshaft timing oil control valve controlled the spool valve using duty cycle control from the engine control module (ECM) – this allowed hydraulic pressure to be applied to the advanced or retarded side of the VVT-i controller, causing rotation in the VVT-i controller vane circumferential direction to vary intake and exhaust valve timing. Once target timing was attained, valve timing was held by keeping the camshaft timing oil control valve in its neutral position.

When the engine was stopped, a lock pin locked the intake camshaft at the most retarded end and the exhaust camshaft at the most advanced end so that the engine would start properly. There was also an advance assist spring on the exhaust side VVT-i controller – this spring applied torque in the advance direction when the engine was stopped to ensure engagement of the lock pin.

The ECM calculated optimal valve timing for the driving condition according to engine speed, intake air mass, throttle position and engine coolant temperature. Furthermore, the ECM used signals from the camshaft position sensor and the crankshaft position sensor to detect actual valve timing, thus providing feedback control to achieve the target valve timing.

Intake

The 1AR-FE engine had a plastic intake manifold which contained a rotary type intake air control valve that was activated by Toyota’s ‘Acoustic Control Induction System’ (ACIS). ACIS used a bulkhead to divide the intake manifold into two stages with an intake air control valve in the bulkhead used to vary the effective length of the intake manifold – according to engine speed and throttle valve opening angle – to utilise the effect of inlet pulsations.

The intake manifold also contained a ‘Tumble Control System’ which closed the tumble control valves during cold start and cold running conditions to create a tumble current in the combustion chamber to reduce exhaust emissions. Once the engine had warmed up, the tumble control valve opened to reduce intake resistance.

The 1AR-FE engine had a linkless-type throttle body and Toyota’s ‘Electronic Throttle Control System – intelligent’ (ETCS-i) which controlled throttle valve opening according to with the amount of accelerator pedal effort and the condition of the engine.

Injection

The 1AR-FE engine had L-type sequential multiport fuel injection (SFI) system via twelve-hole, long nozzle-type fuel injectors. To measure air intake density, the 1AR-FE engine used a hot-wire type mass air flow meter. Furthermore, the 1AR-FE engine had pentroof-type combustion chambers and a compression ratio of 10.0:1.

Ignition

The 1AR-FE engine had Toyota’s ‘Direct Ignition System’ (DIS) in which there was one ignition coil (with igniter) for each cylinder. Ignition timing was determined by the ECM based on signals from various sensors.

The 1AR-FE engine had long-reach type iridium-tipped spark plugs (Denso SK16HR11) to reduce the distance from injector to intake valve, preventing fuel from adhering to the intake port walls (wall wetting). Each spark plug was located in the centre of the combustion chamber to improve anti-knocking performance.

The firing order for the 1AR-FE engine was 1-3-4-2.

Exhaust and emissions

The 1AR-FE had a stainless steel exhaust manifold for fast warm-up of the thin-wall, ceramic three-way catalytic converter, while the exhaust pipe used two ball joints. To reduce evaporative emissions, the 1AR-FE engine had a returnless fuel system.

Introduction

Toyota’s 1AZ-FE was a 2.0-litre inline four-cylinder petrol engine. A member of Toyota’s AZ engine family, key features of the 1AZ-FE included its aluminium alloy block and cylinder head, double overhead camshafts, variable intake valve timing and 9.8:1 compression ratio.

For Australia, the 1AZ-FE was offered in the XA20 RAV4 and T250 Avensis Verso (see table below). In the Avensis Verso, the 1AZ-FE engine had a service weight of 123 kg for models with manual transmissions and 117 kg with automatic transmissions.

The 1AZ-FE was upgraded in late 2003, though no Australian-delivered models were offered with this engine. Upgrades for this post-2003 1AZ-FE engine included:

• The introduction of electronic throttle control;
• Revised valve timing; and,
• The adoption of a planar-type air:fuel ratio sensor (integrated with the oxygen sensor) and flat-type knock sensor.

1AZ-FE block

The aluminium alloy cylinder block of the 1AZ-FE engine had 86.0 mm bores and a 86.0 mm stroke for a capacity of 1998 cc. The 1AZ-FE engine had cast iron liners which were manufactured so that their casting exteriors formed large, irregular surfaces (‘spiny type’) for better adhesion between the liners and the cylinder block.

Other features of the 1AZ-FE cylinder block included:

• Air passage holes in the crankshaft bearing area of the cylinder block for better air flow and reduced back pressure at the bottom of the pistons;
• Water jacket spacers which suppressed water flow in the centre of the jackets and guided the coolant around the cylinder bores; and,
• Oil filter and air conditioning compressor brackets that were integrated into the crankcase.

Crankshaft, connecting rods and pistons

The 1AZ-FE engine had a forged steel crankshaft with five journals, eight balance weights and roll-finished pin and journal fillets. The 1AZ-FE’s crankshaft was offset by 10 mm to the thrust side of the cylinder bore centre line to reduce friction; according to Toyota, this design reduced fuel consumption by between one and three percent.

The connecting rods and caps were made of high-strength steel. To reduce mass, nut-less type plastic region tightening bolts were used.

The 1AZ-FE engine had aluminium alloy pistons. While the piston head had a taper squish shape, the piston skirt was coated with resin to reduce frictional losses.

Cylinder head

The 1AZ-FE engine had an aluminium alloy cylinder head which was mounted upon a steel-laminate type head gasket; to increase the sealing surface, a shim was used around the cylinder bore. To reduce mass, the 1AZ-FE engine had a magnesium alloy die-cast cylinder head cover.

Camshafts

The 1AZ-FE engine had double overhead camshafts (DOHC or Toyota’s ‘Twin Cam’) that were driven by a roller chain which had an 8 mm pitch and was lubricated by an oil jet. The chain tensioner used a spring and oil pressure to maintain chain tension; it also used a ratchet type non-return mechanism.

Valves

The 1AZ-FE engine had four valves per cylinder – two intake and two exhaust – that were positioned at a 27.5 degree included valve angle. The intake valves each had a diameter of 34.0 mm, while exhaust valve diameter was 29.5 mm. Furthermore, the 1AZ-FE engine used shimless type valve lifters that provided a large cam contact surface.

Variable Valve Timing – intelligent (VVT-i)

The 1AZ-FE engine featured Toyota’s ‘Variable Valve Timing – intelligent’ (VVT-i) system which varied intake valve timing according to driving conditions (based engine speed, vehicle speed, intake air mass and flow, throttle position and engine coolant temperature). The ECM used signals from the camshaft position sensor and crankshaft position sensor to detect the actual valve timing, thereby providing feedback control to achieve the target valve timing.

For the pre-2003 1AZ-FE engine, intake valve overlap ranged from -1 to 49 degrees relative to crankshaft angle, intake duration was 236 degrees and exhaust duration was 228 degrees.

• A camshaft timing oil control valve that was mounted adjacent to the inlet camshaft gear wheel; and,
• A VVT-i controller which had a four-bladed vane and was built onto the inlet camshaft timing gear.

The camshaft timing oil control valve was a spool-type valve that was controlled – via the ECU – by a coil and plunger; the ECU could signal ‘advance’, ‘hold’ or ‘retard’. When the ECU required a change in intake valve timing, it signalled the oil control valve to provide oil pressure to either the ‘advance’ or ‘retard’ side of the four vane chambers.

Inlet cam timing was set to the maximum ‘retard’ position for engine start-up, operation at low engine temperature, idle and engine shutdown. Furthermore, a locking pin in the controller locked the camshaft timing in the maximum ‘retard’ position for engine start-up and immediately after start-up (until oil pressure is established) to prevent any knocking noise.

Intake and throttle

The 1AZ-FE engine had a big bore, long-branch inlet that was made of plastic (to reduce heat transfer to the inlet charge), a resonator to reduce induction noise and vertical intake ports.

For XA20 RAV4 models with manual transmissions and all Avensis Verso models, the throttle body contained a spherical-plated throttle valve that, according to Toyota, provide greater pedal control and improved acceleration feel. The throttle had an additional spherical plate on one half of the butterfly valve to ‘spherical curve in the relationship between throttle opening angle and intake air volume to improve driveability in the initial phase of throttle opening’. Furthermore, the throttle body was water-heated.

From late 2003, the upgraded 1AZ-FE engine featured Toyota’s ‘Electronic Throttle Control System – intelligent’ (ETCS-i) which consisted of an electronic throttle body with a built-in contactless throttle position sensor and throttle control motor.

Injection

The 1AZ-FE engine had electronically controlled sequential fuel injection via 12-hole injector nozzles that were mounted in the inlet ports to prevent wall wetting and fuel adhesion to the walls of the port. The fuel injection system used a hot-wire L-type air flow meter to measure intake air volume, while two air:fuel ratio sensors in the exhaust headers were used to achieve a stoichiometric air:fuel mixture.

The 1AZ-FE engine had pentroof-type combustion chambers with a slanted (oblique) squish design to improve thermal efficiency and reduce the likelihood of engine knock (pre-ignition). Specifically, the squish angle was shaped obliquely along the wall surface of the combustion chamber to improve airflow, promote swirl and increase the speed of flame travel.

The 1AZ-FE engine had a compression ratio of 9.8:1.

Ignition

The 1AZ-FE engine had centrally located, iridium-tipped spark plugs. With the Toyota ‘Direct Ignition System’ (DIS) an ignition coil with an integrated igniter was used for each cylinder. Furthermore, the 1AZ-FE engine had Toyota’s ‘Electronic Spark Advance’ (ESA) which selected optimal ignition timing in accordance with inputs from sensors.

The firing order for the 1AZ-FE engine was 1-3-4-2.

Exhaust

The pre-2003 engine 1AZ-FE engine had:

• Double-walled stainless steel extractor-style exhaust headers;
• Three-way catalytic converters located downstream of the exhaust headers; and,
• A two-stage muffler.

For the upgraded 1AZ-FE engine introduced in late 2003, the two three-way catalytic converters were integrated into a single three-way catalytic converter and a three-way catalytic converter was added below the exhaust manifold and under the floor.