Low Pressure Reading Swings Between 25-40 Psi With Compressor Off

Introduction

The FA20D engine was a 2.0-litre horizontally-opposed (or 'boxer') four-cylinder petrol engine that was manufactured at Subaru'southward 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 equally the 4U-GSE earlier adopting the FA20 name.

Key features of the FA20D engine included it:

• Open deck pattern (i.e. the space betwixt the cylinder bores at the pinnacle of the cylinder block was open);
• Aluminium alloy block and cylinder head;
• Double overhead camshafts;
• Four valves per cylinder with variable inlet and exhaust valve timing;
• Direct and port fuel injection systems;
• Pinch ratio of 12.five:1; and,
• 7450 rpm redline.

FA20D cake

The FA20D engine had an aluminium blend cake 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 bandage fe liners.

Cylinder head: camshaft and valves

The FA20D engine had an aluminium blend cylinder head with concatenation-driven double overhead camshafts. The four valves per cylinder – 2 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 spring, check ball and check brawl jump. Through the use of oil force per unit area and spring force, the lash adjuster maintained a constant nix 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 as Subaru's 'Dual Active 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 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 elapsing was 252 degrees.

The camshaft timing gear assembly contained advance and retard oil passages, also as a detent oil passage to make intermediate locking possible. Furthermore, a thin cam timing oil control valve assembly was installed on the forepart surface side of the timing chain cover to make the variable valve timing mechanism more than compact. The cam timing oil control valve associates 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 motion to either the correct (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 use force per unit area to the advance/retard hydraulic chamber through the advance/retard 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 by hydraulic force per unit area from the oil pump, the detent oil passage would become blocked and 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 state on the exhaust side, to fix 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 sparse rubber 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 design enhanced the engine induction racket heard in the cabin, producing a 'linear intake sound' in response to throttle application.

In contrast to a conventional throttle which used accelerator pedal endeavor to decide 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 control, stability control and cruise control functions.

Port and directly injection

The FA20D engine had:

• A direct injection system which included a high-pressure fuel pump, fuel delivery pipage and fuel injector associates; and,
• A port injection system which consisted of a fuel suction tube with pump and judge 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, according to engine load and engine speed, to optimise the fuel:air mixture for engine conditions. According to Toyota, port and direct injection increased performance beyond the revolution range compared with a port-only injection engine, increasing power by up to ten kW and torque by up to 20 Nm.

As per the table below, the injection arrangement 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 by 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, ameliorate fuel efficiency and reduce emissions;
• Medium engine speeds and loads: direct injection merely to use the cooling event of the fuel evaporating every bit it 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 menses volume.

The FA20D engine used a hot-wire, slot-in type air flow meter to measure intake mass – this meter allowed a portion of intake air to flow through the detection area so that the air mass and flow rate could be measured directly. The mass air flow meter besides 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 system whereby an ignition scroll 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 coil associates.

The FA20D engine had long-reach, iridium-tipped spark plugs which enabled the thickness of the cylinder caput sub-assembly that received the spark plugs to be increased. Furthermore, the water jacket could exist extended near the combustion chamber to enhance cooling functioning. The triple ground electrode type iridium-tipped spark plugs had sixty,000 mile (96,000 km) maintenance intervals.

The FA20D engine had flat blazon knock control sensors (non-resonant type) fastened to the left and right cylinder blocks.

Exhaust and emissions

The FA20D engine had a four-2-1 exhaust manifold and dual tailpipe outlets. To reduce emissions, the FA20D engine had a returnless fuel arrangement with evaporative emissions control that prevented fuel vapours created in the fuel tank from being released into the atmosphere by catching them in an activated charcoal canister.

Uneven idle and stalling

For the Subaru BRZ and Toyota 86, at that place accept been reports of

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

that were accompanied by

• the 'check engine' light illuminating; and,
• the ECU issuing mistake 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 aberration 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 subsequently manufactured to a 'tighter specification'.

There have been cases, however, where the vehicle has stalled when coming to remainder 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 event, the hydraulically-controlled camshaft could not respond to ECU signals. If this occurred, the cam sprocket needed to be replaced.

cunninghamamentem98.blogspot.com

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

Share this post