ZR engines was introduced in the fall of 2006 for domestic market. In the summer of 2007 first Valvematic versions released. It superseded a several predecessors: 3ZZ-FE ⇒ 1ZR-FE/FAE, 1ZZ-FE ⇒ 2ZR-FE/FAE, 1AZ-FE/FSE ⇒ 3ZR-FE/FAE. In the early 2010s ZR was installed in B/C/D-class cars (Yaris, Corolla, Avensis, Premio families), light-SUV (RAV4), vans (Noah, Isis).
Beside to the modern analogues, the performance of 1.6 and 1.8 vm seems not bad, but 2.0 and 2.0 vm are at average level. Fuel economy is "good" (in a conventional category "up to 10 lt per 100 km"), note a low consumption at cruising speeds on the highways and appreciable dependence on the ambient temperature. But economy can be sooner the result of more effective CVT implementation, so ZR unitized with classical automatic transmission have not low consumption.
Engine mechanical / Cylinder block
The cylinder block - aluminium "open deck" with thin cast iron liners. The liners are fused into block and their special rough outer surface promotes strong connection. The wall thickness between the cylinders is 7 mm only, no overhaul with reboring provided by manufacturer. Sometimes the circumstances force to perform boring or liners replacement, but the final result of such "hick-tuning" is difficult to name "Toyota".
The axis of the crankshaft has been shifted by 8 mm relative to the cylinder axis lines ("desaxage"), thus reducing the lateral component of the force exerted by the piston to the cylinder wall, reducing wear. This solution has already been used at AZ and NZ, but absent at ZZ.
The crankshaft has 8 balance weights, narrowed journals and individual main bearing caps. The massive alloy crankcase mounted to block also performs the function of the sump upper part. Compact steel lower oil sump can be detached without removal of other components.
The pistons are of aluminium alloy, compact T-shaped in projection, with cutted skirt. The groove for the upper compression ring is anodized, the edge of the upper compression ring and oil scraper have anti-wear PVD coating. The pistons are connected to the rods with fully floating pins.
The engine installed vertically, not impeding maintenence. The powertrain have four mounts, the right top is "liquid-filled".
Engines have the same cylinder bore with the piston stroke different. 1.8 is a just long-stroke, but 2.0 have record D/S ratio. As a result, the average piston speed at max power rpm is about 22 m/s, which was once considered as upper limit even for racing motors. In spite of the lightweight pistons and new technologies, it is not good for durability of purely "civil" engine. And some problems of oil consumption are directly related to this "record".
Engine mechanical / Cylinder head
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 roller rockers and lash adjusters are used instead of adjusting tappets of previous series. The angle between the intake and exhaust valves is 29°, rather large for Toyota.
The head cover is made of alloy and provided with oil delivery pipe for the rockers lubrication.
Valvematic engines are equipped with vane type vacuum pump driven by rear side of exhaust camshaft (for brake booster operation).
Engine mechanical / Timing drive
Timing drive - 16-valve DOHC, driven by single-row roller chain (pitch 8 mm). Hydraulic tensioner (with ratchet mechanism) is installed outside the cover.
The design of cast aluminium timing chain cover is complicated - there are the water pump and the oil nozzle line for chain lubrication in cover installed.
VVT actuators both on the inlet and outlet camshafts are installed (DVVT - Dual Variable Valve Timing). Timing variations range - 55° for intake and 40° for exhaust.
Each of the engines has a modification with continuous variable lifting of the intake valves (Valvematic), more about this feature - "Valvematic system".
As usually, critical chains stretch and consequently replacement need occurs at 120.000-150.000 km. Together with the chain replacement it would be appropriate also replace other components (sprockets, tensioner, guides), as used ones contribute to a rapid wear of a new chain. But the camshaft sprocket is assembled with quite expensive VVT actuator.
Trochoid type oil pump is installed in the crankcase and is driven by short additional chain (similar to AZ series). It improves performance after cold start, but complicates the construction.
Valvematic engines are equipped with mechanical bypass valve, which allows to regulate oil flow and pressure depending on engine speed.
Oil nozzles for lubrication and cooling of the pistons are provided.
The oil filter layout is not convenient - horizontally at bulkhead side - in contrast to the previous series with vertically installed filters (opening up), which does not allow the oil to drain from the filter after engine stalled and contributes to the rapid pressure up after starting. Since 2008, the collapsible filter with replaceable cartridges are used.
The cooling system is implemented without any "modern" solutions - pump drive by outer side of serpentine belt, mechanical thermostat, heated throttle body.
Valvematic engines are 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
Plastic intake manifold is mounted at front side, steel exhaust manifold - at bulkhead side (similar to ZZ). Beyond the manifold the pre-catalyst is installed, a little further - the second catalyst combined with the main silencer.
Valvematic engines are equipped with ACIS system allows to increase output by switching the effective length of the intake path. 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 short path.
Fuel injection - traditional multipoint, sequential under normal conditions, at low temperature and low speed paired or grouped injection can be performed.
- Mass air flow sensor (MAF) - "hot wire" type, combined with the intake temperature sensor.
- Throttle valve - 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 sensor - wideband "flat" piezoelectric, unlike the old type of resonant knock sensors it feels a wider range of vibration frequencies.
- At 1ZR-FE conventional planar type oxygen sensor (89465-) is installed (advantage - more rapid heating), the other engines are equipped with air-fuel ratio sensor (AFS) (89467-), Downstream sensor - standard oxygen (older "cap" type).
- Injectors with elongate nozzle are installed in the cylinder head and the fuel is injected as close as possible to the intake valves. This gives a meager contribution to "ecology", but at low winter temperatures the gasoline sometimes does not have time enough to evaporate.
- Fuel supply - without return line, pulsation damper - internal in the fuel rail. In addition to the pressure regulator and level gauge sensor, EVAP canister is combined with the fuel pump in the tank.
Ignition system - DIS-4 (separate coil for each cylinder). Spark plugs - thin "iridium" SC20HR11 with long threaded portion, hex 14 mm.
Charging system - with conventional or segment conductor type alternators with one-way clutch in the pulley, 90-100 A output. For Valvematic engines continuously charging of battery is carried out during deceleration, but in steady-state mode cycles of charging and discharging of the battery are alternates for maximum efficiency. More complex control system required to use the battery temperature sensor and current sensor.
Starting system - conventional starters with a planetary gear, 0.8-1.1 kW power.
Auxiliary drive - by single serpentine belt, without tensioner (tension adjusting - by alternator moving).
Previous ZZ series problems of oil consumption affected the reputation of all new engines of Toyota - and not in vain - the phenomenon of oil consumption at new ZR engines (2-3 years old) occurred again. Not so scary (as for German motors with "liter per thousand") but 200-300 ml per 1000 km is not considered critical now. Although, if for ZZ high oil consumption clearly indicates mechanical problems (at least with piston rings), then at ZR it can be consequences of recommended extremely liquid energy-saving 0W-20 oil of 0W-20 application, so using of a more adequate viscosity can solve the problem. Toyota mentioned oil consumption as problems in TSB since 2008.
In TSBs we can found the other possible problems of ZR series - difficult starting and misfiring due to increased soot deposits in the combustion chambers (2009), usual EVAP trouble codes (2009-2011), camshaft sprocket replacement because of VVT actuator knocking (2009), water pump leaks and noise (2009-2010), fuel cut-off mode problems (2011), warm start problems (2011), defects of alternator pulley (2009-2010)... And sure, famous "feature" of knocking at Valvematic engine top (so good audible with oil filler cap removed) due to vacuum pump operation.
Absence of destructive failures within the warranty period, the normal winter starting and a non-extreme fuel consumption - it is already an achievement for modern engines. ZR series can be considered "normal" - better than ZZ and AZ (especially D-4), worse than NZ and AR. But Valvematic versions are too complicated and have needless problems.