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Introduction

The FA20D engine was a 2.0-litre horizontally-opposed (or 'boxer') four-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 it as the 4U-GSE earlier adopting the FA20 name.

Fundamental features of the FA20D engine included it:

• Open deck pattern (i.east. the space between the cylinder bores at the top of the cylinder block was open up);
• Aluminium blend block and cylinder head;
• Double overhead camshafts;
• Four valves per cylinder with variable inlet and exhaust valve timing;
• Direct and port fuel injection systems;
• Compression ratio of 12.five:ane; 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 capacity of 1998 cc. Within the cylinder bores, the FA20D engine had cast iron liners.

Cylinder caput: camshaft and valves

The FA20D engine had an aluminium alloy cylinder caput with concatenation-driven double overhead camshafts. The four valves per cylinder – two intake and 2 exhaust – were actuated by roller rocker arms which had congenital-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 spring, check ball and check ball spring. Through the use of oil pressure level and leap force, the lash adjuster maintained a constant nil valve clearance.

Valve timing: D-AVCS

To optimise valve overlap and utilise frazzle pulsation to enhance cylinder filling at high engine speeds, the FA20D engine had variable intake and frazzle valve timing, known as Subaru's 'Dual Agile Valve Control System' (D-AVCS).

For the FA20D engine, the intake camshaft had a sixty degree range of adjustment (relative to crankshaft angle), while the exhaust camshaft had a 54 degree 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 contained accelerate and retard oil passages, as well equally a detent oil passage to make intermediate locking possible. Furthermore, a thin cam timing oil command valve assembly was installed on the forepart surface side of the timing concatenation comprehend to make 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 assembly.

To alter cam timing, the spool valve would be activated by the cam timing oil control valve assembly via a signal from the ECM and movement to either the right (to advance timing) or the left (to retard timing). Hydraulic force per unit area in the accelerate chamber from negative or positive cam torque (for advance or retard, respectively) would apply pressure to the advance/retard hydraulic sleeping accommodation through the advance/retard bank check valve. The rotor vane, which was coupled with the camshaft, would then rotate in the advance/retard management against the rotation of the camshaft timing gear assembly – which was driven by the timing chain – and accelerate/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 by spring power, and maximum advance country on the frazzle side, to prepare 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 condom tube to transmit intake pulsations to the cabin. When the intake pulsations reached the sound creator, the damper resonated at certain frequencies. According to Toyota, this blueprint enhanced the engine induction noise heard in the cabin, producing a 'linear intake sound' in response to throttle awarding.

In contrast to a conventional throttle which used accelerator pedal effort to make up one's mind throttle angle, 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 bending. Furthermore, the electronically controlled throttle regulated idle speed, traction command, stability command and cruise control functions.

Port and direct injection

The FA20D engine had:

• A direct injection system which included a loftier-pressure fuel pump, fuel commitment pipe and fuel injector assembly; and,
• A port injection system which consisted of a fuel suction tube with pump and estimate assembly, fuel pipe sub-associates and fuel injector assembly.

Based on inputs from sensors, the ECM controlled the injection book and timing of each type of fuel injector, according to engine load and engine speed, to optimise the fuel:air mixture for engine weather. According to Toyota, port and straight injection increased performance beyond the revolution range compared with a port-just injection engine, increasing power by upwards to 10 kW and torque past up to 20 Nm.

As per the table below, the injection system had the following operating conditions:

• Cold start: the port injectors provided a homogeneous air:fuel mixture in the combustion bedchamber, 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 straight injection for a homogenous air:fuel mixture to stabilise combustion, improve fuel efficiency and reduce emissions;
• Medium engine speeds and loads: direct injection just to utilise the cooling outcome of the fuel evaporating as information technology entered the combustion chamber to increase intake air volume and charging efficiency; and,
• High engine speeds and loads: port injection and direct injection for high fuel menstruum book.

The FA20D engine used a hot-wire, slot-in type air flow meter to mensurate intake mass – this meter allowed a portion of intake air to period through the detection area so that the air mass and catamenia rate could exist measured directly. The mass air flow meter also had a born intake air temperature sensor.

The FA20D engine had a compression ratio of 12.5:1.

Ignition

The FA20D engine had a direct ignition organization whereby an ignition roll 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 ringlet associates.

The FA20D engine had long-reach, 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 nearly the combustion chamber to enhance cooling performance. The triple basis electrode blazon iridium-tipped spark plugs had 60,000 mile (96,000 km) maintenance intervals.

The FA20D engine had flat type knock control sensors (not-resonant type) fastened to the left and correct cylinder blocks.

Exhaust and emissions

The FA20D engine had a 4-two-i exhaust manifold and dual tailpipe outlets. To reduce emissions, the FA20D engine had a returnless fuel system with evaporative emissions control that prevented fuel vapours created in the fuel tank from being released into the atmosphere by communicable them in an activated charcoal canister.

Uneven idle and stalling

For the Subaru BRZ and Toyota 86, there take been reports of

• varying idle speed;
• crude idling;
• shuddering; or,
• stalling

that were accompanied by

• the '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 acquired the ECU to find an abnormality in the cam actuator duty cycle and restrict the operation of the controller. To fix, Subaru and Toyota developed new software mapping that relaxed the ECU's tolerances and the VVT-i/AVCS controllers were afterward manufactured to a 'tighter specification'.

At that place take been cases, however, where the vehicle has stalled when coming to balance and the ECU has issued mistake 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.

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Source: http://www.australiancar.reviews/Subaru_FA20D_Engine.php

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