GR series introduced first in 2003 for domestic Japanese market. Over time, it replaced previous V6 series MZ and VZ, as well as the legendary R6 series G and JZ. At 2010s installed in wide range of models - C/D/E-class cars, vans, mid- and full-size SUV and pickups. Because they are difficult to be attributed as "mass", only its diversity is interesting.
1GR-FE (4.0 EFI VVT) type'04 - longitudinal layout, multipoint injection, mono-VVT. Installed in: 4Runner 210, FJ Cruiser, Fortuner 50, Hilux 20..120, Hilux Surf 210, LC 200, LC 70, LC Prado 120, Tacoma 200, Tundra 30..50.
1GR-FE (4.0 EFI DVVT) type'09 - longitudinal layout, multipoint injection, Dual-VVT. Installed in: 4Runner 280, FJ Cruiser, GX 150, LC 200, LC Prado 150, Tacoma 200, Tundra 50.
2GR-FE (3.5 EFI DVVT) - transverse layout, multipoint injection. Installed in: Alphard 20, Avalon 30..40, Aurion 40, Blade, Camry 40..50, ES 40..60, Estima 50, Harrier 30, Highlander 40, Mark X Zio, Previa 50, RAV4 30, RX 30..L10, Sienna 20..30, Vanguard, Venza, Lotus Evora.
2GR-FKS (3.5 D-4S DVVT-iW) - transverse layout, combined injection, VVT-iW and Miller / Atkinson cycle operation mode. Installed in: RX L20.
2GR-FKS (3.5 D-4S DVVT-iW) - longitudinal layout, combined injection, VVT-iW and Miller / Atkinson cycle operation mode. Installed in: GS L10, Tacoma 300.
2GR-FSE (3.5 D-4S DVVT) - longitudinal layout, combined injection. Installed in: Crown 180..200..210, GS 190..L10, IS 20..30, Mark X 120..130, RC.
2GR-FXE (3.5 EFI DVVT) - transverse layout, multipoint injection, for hybrid vehicles. Installed in: RX L10, Highlander 40.
2GR-FXE (3.5 D-4S DVVT) - longitudinal layout, combined injection, for hybrid vehicles. Installed in: Crown 210, GS L10.
2GR-FXS (3.5 D-4S DVVT-iW) - transverse layout, combined injection, VVT-iW and Miller / Atkinson cycle operation mode, for hybrid vehicles. Installed in: RX L20.
2GR-FZE (3.5 EFI DVVT) - transverse layout, multipoint injection, supercharged. Installed in: TRD Aurion, Lotus Evora, Exige.
3GR-FE (3.0 EFI DVVT) - longitudinal layout, multipoint injection. Installed in: Crown 180..200 CHN, GS 190, IS 20, Reiz 120..130.
3GR-FSE (3.0 D-4 DVVT) - longitudinal layout, direct injection. Installed in: Crown 180..200, GS 190, Mark X 120.
4GR-FSE (2.5 D-4 DVVT) - longitudinal layout, direct injection. For Toyota brand models at Japanese market since the early 2010s used deforced variant. Installed in: Crown 180..200..210, GS L10, IS 20..30, Mark X 120..130.
5GR-FE (2.5 EFI DVVT) - longitudinal layout, multipoint injection, for Chinese market. It is not a version of 4GR, but separate motor on the basis of 3GR-FE. Installed in: Crown 180..200 CHN, Reiz 120..130.
6GR-FE (4.0 EFI DVVT) - longitudinal layout, multipoint injection, for Chinese market commercial vehicles. Analogue of 1GR-FE type'09. Installed in: Coaster 50 CHN.
7GR-FKS (3.5 D-4S DVVT-iW) - longitudinal layout, combined injection, VVT-iW and Miller / Atkinson cycle operation mode, for Chinese market. Analogue of 2GR-FKS. Installed in: LC Prado 150 CHN.
The cylinder block - aluminium "open deck" with thin cast iron liners, cylinder bank angle is 60°. The liners are fused into block and their special rough outer surface promotes strong connection. There are additional channels for coolant between the cylinders, and there are not spacer in the water jacket of 2GR-FE. Of course, no overhaul with reboring provided.
The oil sump consist of massive upper part (additionally connected to transmission for stiffness) and stamped steel lower sump.
Forged steel crankshaft with 4 journals and 5 balance weights is held by individual main bearing caps, which are fastened by four main bolts and by another two side bolts to block walls for maximum rigidity.
Pistons - of aluminium alloy, compact T-shaped in projection, with cutted skirt, all the same size and the same for each bank (as opposed to MZ series). The groove for the upper compression ring has alumite coating and friction reducing polymer coating is applied on the skirt. Thin rings have protective coatings: upper compression - by PVD, lower - anti-corrosion, oil scraper - by gas nitriding. The pistons are connected to the rods with fully floating pins.
The camshafts are installed in a separate housing, which mounted on the cylinder head - it simplifies the design and manufacturing technology of cylinder head. The intake ports are paired, to improve the air flow characteristics the diameter decreases towards the combustion chamber. There are valve adjusters and roller rockers in the valve mechanism. The head covers are made of alloy and provided with oil delivery pipe for the rockers lubrication.
Timing drive is "two-step". From the crankshaft by the primary roller chain (pitch 9.525 mm) intake camshafts are driven, and two short secondary chains for exhaust camshafts drive are used. Primary circuit tensioner - with a ratchet mechanism, spring and return valve, secondary chain tensioner have not ratchet, but also is spring enforced. The chains are lubricated by separate oil nozzles.
Camshaft cams - with a concave profile (thus increasing valve lift at the beginning and at the end of the opening phase, which improves the cylinder admission).
VVT actuators both on the inlet and outlet camshafts are installed (DVVT - Dual Variable Valve Timing). Timing variations range - 40° for intake and 35° for exhaust. The auxiliary spring is installed in VVT actuator of exhaust camshaft to apply a torque to the rotor in the advance direction for secure locking it with pin after engine stall.
The water pump and oil pump are installed in cast timing chain cover, respectively, oil and coolant passages in the cover are provided.
Cycloid oil pump in chain cover is driven directly by the crankshaft, the excess oil is not drain to sump but feed back to the pump inlet. Oil nozzles that lubricate and cool the pistons are provided.
The collapsible filter with replaceable cartridges are used, filter housing is built into the upper sump.
Cooling system is classic: pump drive by outer side of serpentine belt, pump impeller of stainless steel, mechanical thermostat (80-84°C). The throttle body is heated to counteract freezing. Some versions are equipped with oil cooler.
The engine was equipped with separate fan motor control unit, which allows to adjust fan speed depending on the coolant temperature, refrigerant pressure, vehicle speed and engine speed.
Intake and exhaust
There are ACIS valve with electrical drive in the upper intake manifold installed, to change the effective length of the intake for output increase. At low and medium speed and high load ACIS valve is closed and the air flows via long path, in other conditions the valve is opened and air flows via shorter path.
AICS vacuum actuator closes one of the two channels between the air inlet and air filter. At low and middle speed the valve closes one of the channels, so the air passes to filter via smaller hole, which helps to reduce noise. At high speeds and wide open throttle both channels are opened to increase intake efficiency.
Some models have the muffler with a mechanical valve that regulates the flow of exhaust gases. At low speed closed valve helps to reduce noise, at high speeds it is opened reducing the back-pressure.
Fuel injection system (EFI)
Fuel injection - multipoint. Under normal conditions - sequential, once per cycle for each cylinder, at low temperature and low speed group injection can be performed. Fuel supply - without return line, pulsation damper - external on the fuel rail (in some versions, an additional damper can be installed in the line before the fuel feed pipe), the collector is made of plastic. The speed of the fuel pump is regulated by ECM via resistor and relay. EVAP absorber is installed near the fuel tank.
Throttle - fully electronically controlled (ETCS): DC motor, dual-channel non-contact position sensor (Hall effect). ETCS performs some functions of traction control (TRC) and stabilization (VSC).
Accelerator pedal position sensor - dual-channel non-contact (Hall effect). Camshaft position sensors - MRE type (magnetoresistive) , provide a digital output signal and work properly at low engine speed. Knock sensors - "flat" wideband piezoelectric, installed on each bank at the middle cylinder zone. Mass air flow sensor (MAF) - "hot wire" type, combined with the intake temperature sensor. Upstream - planar air-fuel ratio sensor (AFS), downstream - traditional oxygen sensor.
To reduce vibrations an active front engine mount is used (operates at speed below 900 rpm). ECM commands VSV to supply vacuum to the mount changing the pressure in the air chamber. The diaphragm vibrates and transmits vibrations through the liquid to the rubber part. So the mount internal vibration compensates engine vibration at idling. The desired frequency of vibration is regulated by selective orifices and vacuum drain hose.
Ignition system - DIS-6 (separate coil for each cylinder). Spark plugs - "iridium" (Denso FK20HR11 - central electrode of iridium alloy, side electrode of platinum), with a long threaded portion (thereby cooling channel can be expanded in the head to improve heat dissipation).
Alternator - with double segment coil and one-way clutch in the pulley (return current 100/130A). Double coil (two sets of three-phase windings with a shift of 30°) reduces electrical interference and noise at high load. One-way clutch with spring is installed between the inner and outer portions of the pulley to transmit torque only in the direction of rotation of the crankshaft, reducing the load on the drive belt.
Starting system - new 1.7 kW starter with planetary gear and segment armature coil and permanent magnets instead the field coil.
Auxiliary drive - by serpentine belt with automatic spring tensioner.
Specific failures of 2GR-FE.
• Usual problem of water pump leaking and noise, so the pump should be just considered as consumable with a life time about 40-60.000 km.
• The failure of the ignition coils (until 2010, part # 90919-02251) - prescribed to replace the coils with modified.
• Noise from head cover area at starting and possible errors related to the valve timing - prescribed a complicated procedure for replacing the valvetrain components of the sprockets to the camshafts and carriers assembly. VVT sprocket problems are standard of almost all GR engines.
• Errors associated with VVT control valves (until 2011) - prescribed faulty valves replacement.
• Idle speed control system problems and DTCs (until 2010) - prescribed replacement of the throttle body assembly.
• Alternator pulley one-way clutch failure (until 2012) - prescribed installation of new pulleys (a common disease of GR series).
• Oil cooler hose leaks (until 2012, part 15767-31010).
• Oil leak from under the cylinder head cover (until 2007) - prescribed replacement of camshaft carriers.
• Difficult restarting at low temperatures (some models until 2013) - replacement of the junction box..
• Fuel pump resistor failure (some models until 2007).
Indirect deficiencies are not associated with the reliability of the engine:
• As for most models with high performance transverse powertrain reduced transmission life time (as in the case of "famous" U660).
• V6 transverse layout makes access to engine significantly difficult, so for a number of works front side disassembly required or engine hanging.
Early version (type'2004) have a number differences beside the rest of GR engines.
• "Mono"-VVT - adjustable timing for intake only, in range of 50°.
• The cylinder heads are traditional, without camshafts carrier, without hydraulic lash adjusters.
• There are not spacer in the water jacket.
• More complex crankshaft shape (9 counterweights).
• More massive piston with less reduced skirt.
• The oil filter is installed at he engine top with oil cooler.
• The main cooling fan is mechanical belt driven, mounted with silicone fluid filled coupling, which is controlled by the bimetallic thermoelement, to provides a desired dependence between temperature and fan speed.
• Unusual high RON requirements even for Japanese market version (Regular - only in North America).
• Some models was equipped by additional fuel tank, but simple scheme is implemented - with ejection pump and common filler, without switching system.
• To control the performance of the fuel pump (3 speeds) the separate electronic control unit was installed.
• The fuel system - with return line, the fuel pressure regulator - vacuum, at the intake manifold.
• At the first year of production engines inductive camshaft position sensors was installed..
• ACIS with vacuum actuator instead of the electric drive and somewhat different work algorithm..
• Spark plugs with a long threaded portion, but of conventional materials (Denso K20HR-U11, NGK LFR6C-11).
• Starters - modern with a planetary gear and segment armature coil as well more powerful (2 kW) conventional with reducer (for cold climate).
The second variant (type'2009) was structurally similar to other GR motors. The exhaust timing adjusting (the range is 40° for intake and 35° for exhaust), the camshaft carriers, the spacer in the cooling jacket, more compact pistons, simplified crankshaft were implemented, collapsible oil filter and oil cooler are moved to a separate bracket under the engine, more advanced spark plugs are used (Denso SK20HR11), the exhaust air injection system was applied.
• No extra rubber elements in the lubrication system, simplified valvetrain - automatically mean the absence of relevant problems specific to 2GR-FE. The timing chain life time is quiet good. Some knocking in the engine compartment are often a normal operation sound of EVAP VSV and injectors.
• Minor defects are more common - oil leak from the timing cover, water pump leak, emission control system failures (oxygen sensors, EVAP).
• Known the spark plugs destruction cases because of overtightening.
Taking into account the difference in layout, 3GR MPI is substantially similar to 2GR-FE.
• There is the spacer in the water jacket installed, it allows more intensive coolant circulation near the top of the cylinder, which improves heat dissipation and helps to more evenly thermally load.
• Front engine mounts are liquid filled, active mounts not applied.
• The oil filter is installed horizontally in the front, on the top of upper sump bracket (the sump has a specific for longitudinal layout engines shape). The oil level sensor is installed (limit switch with a float) - if a low level is maintained for more than 40 seconds, the system switches on warning light.
• There is ATF heater in the cooling system installed. Radiator fans - electrical, controlled via a separate control unit.
• The fuel system - with return line, the fuel pressure regulator bilt in the fuel pump module.
• ACIS drive - electrical, operates by algorithm similar to 1GR-FE. Other intake geometry controls are not used.
• ETCS supports SNOW operation mode SNOW, damping response to the accelerator pedal pressing.
• Spark plugs - "iridium", single-electroded (Denso FK20HR11 / NGK ILFR6D11).
Direct injection engines have some differences at mechanical part.
• The higher the compression ratio.
• The fuel injectors are mounted in cylinder head. The shape of the intake port promotes the generation of "reverse swirl" in the cylinder.
• Pistons with a specific shape are different for the left and right banks.
Fuel injection system (D-4)
Fuel injection - direct in the combustion chamber, is synchronized with piston position. The fuel from tank pump is supplied to high pressure pump, than under pressure (4..13 MPa) into the fuel rail, and finally into the cylinders by injectors.
Operation . The engine works in two basic modes:
- Homogeneous mixture mode - injection during the intake stroke, the fuel mixes with air and forms a homogeneous mixture with a composition close to the stoichiometric. Due to the evaporation of injected fuel, air charge in the cylinder is cooled further reduces the possibility of knocking and improves cylinder filling.
- Stratified combustion mode - injection at the end of the compression stroke - the fuel is reflected from the recess of the piston, actively dispersed and vaporized, heading to the spark plug. Although the mixture in whole cylinder is lean, at spark plug area it is rich enough to be ignited by spark and fire the remaining volume. Lean mixture in the remaining volume is less prone to detonation, which allows to increase the compression ratio and increase engine output. Due to the evaporation of injected fuel air charge in the cylinder is cooled further reduces the possibility of knocking. This mode is used after a cold start to accelerate catalyst warm-up.
Injection/supply pump. Single-plunger with control valve, check valve and pulsation damper at inlet. Installed in the rear of the right bank valve cover, driven by exhaust camshaft additional cam. There is an insulating spacer installed between the pump and valve cover to reduce pump heat.
- At inlet stroke the plunger moves downward and fuel draws into the pumping chamber.
- At the beginning of the compression stroke part of the fuel is returned while control valve is open (the specified fuel pressure is set in the range 4-13 MPa).
- At the end of the compression stroke control valve is closed and the pressurized fuel through the check valve is supplied into the fuel rail.
- At the engine start the control valve is opened and the fuel is fed directly into the manifold at regulator pressure (400 kPa).
Fuel rail. Made of aluminium alloy, contains fuel pressure sensor to provide feedback, and a mechanical pressure relief valve (opens the drain line to the tank if the pressure exceeds 15.3 MPa).
Injectors. Slotted nozzle injector injects the fuel into the cylinder as specific shaped spray that draws in a significant amount of air and increases the mass admission. The nozzle protruding in the combustion chamber have special non-stick coating. Sealing teflon (PTFE) rings further reduce vibration.
Injector driver (EDU). The injectors are controlled by a driver, which converts the signal from the control unit in the high-voltage signal to the injectors, ensuring maximum operation speed. After the opening of the nozzle is held opened by low voltage signal.
SCV (swirl control valve) actuator. There is SCV block between the cylinder head and the inlet manifold, which closes one of two inlets channel to each cylinder, depending on the driving conditions. Flaps are driven by electric motor via linkage.
- At low speed, low load, low coolant temperature SCV is closed, air flows through one port, that increases flow speed for better mixture combustion.
- At high loads SCV is opened, air enters through both ports increases filling of cylinders, the vertical vortex in the combustion chamber created, carburetion is improved.
A great advantage of D-4 at GR series - the absence of EGR.
Spark plugs. "Iridium" (Denso FK20HBR11 / NGK ILFR6D11T) - in addition to the platinum electrode contact, added two side electrodes.
As usual for Toyota, the new technical solutions caused a number of different "childhood diseases", especially in comparison with proven JZ and MZ.
• Since the first D-4 engine (infamous 3S-FSE), enough time has passed that the company was able to find the right solutions - and, indeed, control system and fuel system are not more problematical as of MPI engines. The absence of EGR significantly reduced the problem of carbon deposits in the intake manifold and at all related moving elements.
In addition to standard fault of EVAP (absorber module), can be noted two specific defects.
• Problems of AFS and oxygen sensors - not recommended for a long ride with an error related too rich mixture (the manufacturer supposes, that excessive amount of gasoline drains in the motor oil).
• A series of recalls: corrosion of aluminium components of the fuel system - internal corrosion and pressure fluctuations could cause destruction of welding or cracks and major fuel leaks (domestic market until 2005, overseas until 2008), defects of injector ring seals with fuel leak possibility (domestic market until 2005), spontaneously loosened fuel pressure sensor (Japanese market 2007-2009).
The mechanical part condition seems worse:
• Oil leaks at camshaft carriers (until 2008) does not deserve special attention.
• Abnormal sound (knock) in timing drive after starting - a chronic disease, supposedly "fixed" by periodically releases of another type of intake camshaft VVT sprocket (part numbers - 13050-
• Major recall campaigns related to valve springs - foreign matter in the material cause weakening or rupture of the springs, followed by noise during operation and engine stall (4GR-FSE 2005-2008, 2GR-FSE 2007-2008, 3GR-FSE 2006...).
With the exception of the fuel system, construction is similar to the 3GR / 4GR. Differences at the mechanical part include:
- Increased range of variable timing up to 60° (intake) and 35° (exhaust).
- Another type of the piston - for D-4 with a lower compression ratio.
Fuel injection system (D-4S)
Fuel injection - combined: directly in the combustion chamber and multipoint in the inlet ports. At low to medium loads and low speeds - combined injection is applied - homogeneous mixture increases the stability of the combustion process and reduces emissions. At high load - direct injection is applied - the evaporation of the fuel in the cylinder improves the mass admission and reduces the tendency to knocking, which allows to increase the compression ratio.
- Stratified combustion mode. Fuel is supplied in the intake ports on the exhaust stroke. On the intake stroke after the valves are opened a homogeneous mixture flows in the cylinder. At the end of the compression stroke, additional fuel is injected directly into the cylinder, allowing to enrich the mixture near the spark plug. This facilitates the initial ignition, is then distributed on the all lean mixture charge in the remaining volume of the combustion chamber. This mode is applied after a cold start to retard ignition timing and to increase the exhaust gas temperature for accelerate catalyst warming up.
- Homogeneous mixture mode. Fuel is supplied to the intake ports on the exhaust stroke. On the intake stroke after the valves are opened a homogeneous mixture flows in the cylinder, additional fuel is injected directly into the cylinder and uniformly mixed with the incoming charge due to turbulence. Homogeneous air-fuel mixture is compressed and then ignited. Due to the evaporation of injected fuel, air charge in the cylinder is cooled improves cylinder filling.
There are some differences in direct injection system:
• Pressure relief valve is electronically controlled.
• Double-slotted injector nozzles.
• For low pressure injection traditional fuel rail without the return line is provided.
Similar to 2GR-FSE.
Some differences in the mechanical:
- Variable valve timing system VVT-iW - see details. Increased range of variable timing up to 80° (intake) and 50° (exhaust).
- Implemented a possibility of engine operation by Miller / Atkinson cycle - see details.
Some differences in the fuel system:
- Increased range of operating pressure - 2..20 MPa
- Modified pump with roller lifter
- The absence of external pulsation dampers.
- Pressure relief valve built into the pump.
- Pressure sensor in the low pressure line.
1GR-FE / 6GR-FE
3GR-FE / 5GR-FE
3GR-FSE / 4GR-FSE