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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 information technology as the 4U-GSE earlier adopting the FA20 name.

Key features of the FA20D engine included information technology:

• Open up deck pattern (i.eastward. the space betwixt the cylinder bores at the top of the cylinder block was open up);
• Aluminium alloy block and cylinder caput;
• Double overhead camshafts;
• Four valves per cylinder with variable inlet and exhaust valve timing;
• Direct and port fuel injection systems;
• Pinch ratio of 12.5:1; and,
• 7450 rpm redline.

FA20D block

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. Inside the cylinder bores, the FA20D engine had bandage iron liners.

Cylinder head: camshaft and valves

The FA20D engine had an aluminium blend cylinder caput with chain-driven double overhead camshafts. The four 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 arms (which actuated the valves). The hydraulic lash adjuster – located at the fulcrum of the roller rocker arm – consisted primarily of a plunger, plunger spring, bank check ball and check ball leap. Through the use of oil pressure level and spring force, 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 exhaust valve timing, known equally Subaru'southward 'Dual Agile Valve Control System' (D-AVCS).

For the FA20D engine, the intake camshaft had a 60 caste 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 contained advance and retard oil passages, as well every bit a detent oil passage to brand intermediate locking possible. Furthermore, a thin cam timing oil control valve assembly was installed on the front surface side of the timing chain cover to brand the variable valve timing machinery more compact. The cam timing oil command valve assembly operated according to signals from the ECM, controlling the position of the spool valve and supplying engine oil to the advance hydraulic bedchamber or retard hydraulic chamber of the camshaft timing gear assembly.

To alter cam timing, the spool valve would exist activated by the cam timing oil control valve associates via a point from the ECM and movement to either the correct (to advance timing) or the left (to retard timing). Hydraulic force per unit area in the advance chamber from negative or positive cam torque (for advance or retard, respectively) would apply pressure level to the advance/retard hydraulic chamber through the advance/retard cheque 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 past the timing chain – and advance/retard valve timing. Pressed by hydraulic force per unit area 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 accelerate state on the exhaust side, to prepare for the side by side 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 sound creator, the damper resonated at sure frequencies. Co-ordinate to Toyota, this blueprint enhanced the engine induction dissonance heard in the cabin, producing a 'linear intake sound' in response to throttle awarding.

In contrast to a conventional throttle which used accelerator pedal try to make up one's mind 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 prowl control functions.

Port and direct injection

The FA20D engine had:

• A directly injection organisation which included a high-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 guess assembly, fuel pipe sub-assembly and fuel injector assembly.

Based on inputs from sensors, the ECM controlled the injection volume and timing of each type of fuel injector, co-ordinate to engine load and engine speed, to optimise the fuel:air mixture for engine conditions. According to Toyota, port and direct injection increased performance across the revolution range compared with a port-merely injection engine, increasing power by up to 10 kW and torque by upwards to twenty Nm.

As per the table beneath, the injection system had the following operating atmospheric condition:

• Cold start: the port injectors provided a homogeneous air:fuel mixture in the combustion chamber, though the mixture around the spark plugs was stratified by pinch stroke injection from the directly injectors. Furthermore, ignition timing was retarded to raise exhaust gas temperatures and so that the catalytic converter could reach operating temperature more quickly;
• Low engine speeds: port injection and direct injection for a homogenous air:fuel mixture to stabilise combustion, improve fuel efficiency and reduce emissions;
• Medium engine speeds and loads: direct injection but to utilise the cooling effect of the fuel evaporating as information technology entered the combustion chamber to increment intake air volume and charging efficiency; and,
• High engine speeds and loads: port injection and direct injection for loftier fuel menses 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 catamenia through the detection area so that the air mass and flow rate could be measured directly. The mass air flow meter likewise 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 curl 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 near the combustion bedchamber to enhance cooling performance. The triple ground electrode type iridium-tipped spark plugs had 60,000 mile (96,000 km) maintenance intervals.

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

Frazzle and emissions

The FA20D engine had a four-2-1 frazzle manifold and dual tailpipe outlets. To reduce emissions, the FA20D engine had a returnless fuel organization with evaporative emissions control that prevented fuel vapours created in the fuel tank from beingness released into the temper 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;
• rough idling;
• shuddering; or,
• stalling

that were accompanied past

• 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 detect an aberration in the cam actuator duty bike and restrict the performance of the controller. To fix, Subaru and Toyota developed new software mapping that relaxed the ECU'south tolerances and the VVT-i/AVCS controllers were subsequently manufactured to a 'tighter specification'.

There have been cases, however, where the vehicle has stalled when coming to rest and the ECU has issued mistake codes P0016 or P0017 – these symptoms accept been attributed to a faulty cam sprocket which could crusade oil pressure loss. As a event, the hydraulically-controlled camshaft could non 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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