Demi Gods and Semi Devils 1997 Tvb Review
Introduction
The FA20D engine was a 2.0-litre horizontally-opposed (or 'boxer') 4-cylinder petrol engine that was manufactured at Subaru's engine plant in Ota, Gunma. The FA20D engine was introduced in the Subaru BRZ and Toyota ZN6 86; for the latter, Toyota initially referred to information technology as the 4U-GSE earlier adopting the FA20 name.
Cardinal features of the FA20D engine included it:
- Open deck design (i.eastward. the space between the cylinder bores at the top of the cylinder block was open);
- Aluminium alloy block and cylinder head;
- Double overhead camshafts;
- Four valves per cylinder with variable inlet and frazzle valve timing;
- Direct and port fuel injection systems;
- Compression ratio of 12.5:i; and,
- 7450 rpm redline.
FA20D cake
The FA20D engine had an aluminium alloy block with 86.0 mm bores and an 86.0 mm stroke for a chapters of 1998 cc. Within the cylinder bores, the FA20D engine had cast fe liners.
Cylinder head: camshaft and valves
The FA20D engine had an aluminium alloy cylinder head with concatenation-driven double overhead camshafts. The iv valves per cylinder – two intake and two exhaust – were actuated by roller rocker arms which had built-in needle bearings that reduced the friction that occurred between the camshafts and the roller rocker artillery (which actuated the valves). The hydraulic lash adjuster – located at the fulcrum of the roller rocker arm – consisted primarily of a plunger, plunger jump, cheque brawl and bank check ball leap. Through the utilize of oil pressure level and jump forcefulness, the lash adjuster maintained a constant zero valve clearance.
Valve timing: D-AVCS
To optimise valve overlap and utilise exhaust pulsation to enhance cylinder filling at high engine speeds, the FA20D engine had variable intake and frazzle valve timing, known as Subaru's 'Dual Active Valve Control System' (D-AVCS).
For the FA20D engine, the intake camshaft had a 60 degree range of adjustment (relative to crankshaft angle), while the frazzle camshaft had a 54 caste range. For the FA20D engine,
- Valve overlap ranged from -33 degrees to 89 degrees (a range of 122 degrees);
- Intake duration was 255 degrees; and,
- Exhaust duration was 252 degrees.
The camshaft timing gear assembly independent advance and retard oil passages, as well as a detent oil passage to brand intermediate locking possible. Furthermore, a thin cam timing oil control valve assembly was installed on the front end surface side of the timing chain embrace to brand the variable valve timing mechanism more compact. The cam timing oil control valve assembly operated according to signals from the ECM, controlling the position of the spool valve and supplying engine oil to the advance hydraulic chamber or retard hydraulic chamber of the camshaft timing gear associates.
To modify cam timing, the spool valve would be activated by the cam timing oil command valve assembly via a signal from the ECM and motility to either the right (to accelerate timing) or the left (to retard timing). Hydraulic pressure in the advance chamber from negative or positive cam torque (for advance or retard, respectively) would apply pressure to the advance/retard hydraulic chamber through the advance/retard bank check valve. The rotor vane, which was coupled with the camshaft, would then rotate in the advance/retard direction against the rotation of the camshaft timing gear assembly – which was driven by the timing chain – and advance/retard valve timing. Pressed past hydraulic pressure from the oil pump, the detent oil passage would become blocked so that it did not operate.
When the engine was stopped, the spool valve was put into an intermediate locking position on the intake side past jump ability, and maximum accelerate land on the frazzle side, to set for the next activation.
Intake and throttle
The intake system for the Toyota ZN6 86 and Subaru Z1 BRZ included a 'sound creator', damper and a thin rubber tube to transmit intake pulsations to the cabin. When the intake pulsations reached the audio creator, the damper resonated at certain frequencies. According to Toyota, this design enhanced the engine induction dissonance heard in the cabin, producing a 'linear intake sound' in response to throttle application.
In contrast to a conventional throttle which used accelerator pedal effort to decide throttle bending, the FA20D engine had electronic throttle control which used the ECM to calculate the optimal throttle valve angle and a throttle control motor to control the angle. Furthermore, the electronically controlled throttle regulated idle speed, traction control, stability control and cruise control functions.
Port and straight injection
The FA20D engine had:
- A direct injection organisation which included a loftier-pressure level fuel pump, fuel commitment pipe and fuel injector assembly; and,
- A port injection system which consisted of a fuel suction tube with pump and gauge assembly, fuel pipe sub-assembly and fuel injector assembly.
Based on inputs from sensors, the ECM controlled the injection volume and timing of each blazon of fuel injector, co-ordinate to engine load and engine speed, to optimise the fuel:air mixture for engine conditions. Co-ordinate to Toyota, port and direct injection increased performance across the revolution range compared with a port-but injection engine, increasing ability by upwardly to 10 kW and torque by upward to twenty Nm.
Every bit per the table below, the injection system had the following operating weather condition:
- Cold kickoff: the port injectors provided a homogeneous air:fuel mixture in the combustion bedroom, though the mixture around the spark plugs was stratified past compression stroke injection from the direct injectors. Furthermore, ignition timing was retarded to raise exhaust gas temperatures so that the catalytic converter could reach operating temperature more than quickly;
- Low engine speeds: port injection and directly injection for a homogenous air:fuel mixture to stabilise combustion, better fuel efficiency and reduce emissions;
- Medium engine speeds and loads: straight injection only to utilise the cooling effect of the fuel evaporating as it entered the combustion chamber to increase intake air book and charging efficiency; and,
- High engine speeds and loads: port injection and direct injection for high fuel flow volume.
The FA20D engine used a hot-wire, slot-in blazon air catamenia meter to measure intake mass – this meter allowed a portion of intake air to flow through the detection area then that the air mass and flow charge per unit could be measured directly. The mass air flow meter too had a built-in intake air temperature sensor.
The FA20D engine had a compression ratio of 12.5:ane.
Ignition
The FA20D engine had a direct ignition system whereby an ignition coil with an integrated igniter was used for each cylinder. The spark plug caps, which provided contact to the spark plugs, were integrated with the ignition roll assembly.
The FA20D engine had long-accomplish, iridium-tipped spark plugs which enabled the thickness of the cylinder head sub-assembly that received the spark plugs to be increased. Furthermore, the water jacket could be extended near the combustion chamber to heighten cooling performance. The triple ground electrode type iridium-tipped spark plugs had lx,000 mile (96,000 km) maintenance intervals.
The FA20D engine had apartment type knock control sensors (non-resonant type) fastened to the left and correct cylinder blocks.
Exhaust and emissions
The FA20D engine had a 4-2-i frazzle manifold and dual tailpipe outlets. To reduce emissions, the FA20D engine had a returnless fuel organization with evaporative emissions command that prevented fuel vapours created in the fuel tank from beingness released into the atmosphere by catching them in an activated charcoal canister.
Uneven idle and stalling
For the Subaru BRZ and Toyota 86, there have been reports of
- varying idle speed;
- rough idling;
- shuddering; or,
- stalling
that were accompanied by
- the 'bank check engine' light illuminating; and,
- the ECU issuing fault codes P0016, P0017, P0018 and P0019.
Initially, Subaru and Toyota attributed these symptoms to the VVT-i/AVCS controllers not meeting manufacturing tolerances which caused the ECU to detect an abnormality in the cam actuator duty bike and restrict the operation of the controller. To fix, Subaru and Toyota developed new software mapping that relaxed the ECU'southward tolerances and the VVT-i/AVCS controllers were after manufactured to a 'tighter specification'.
There take been cases, however, where the vehicle has stalled when coming to rest and the ECU has issued error codes P0016 or P0017 – these symptoms have been attributed to a faulty cam sprocket which could cause oil force per unit area loss. Every bit a result, the hydraulically-controlled camshaft could not respond to ECU signals. If this occurred, the cam sprocket needed to be replaced.
Source: http://www.australiancar.reviews/Subaru_FA20D_Engine.php