HOLDEN GEN III V8, Обучение по обслуживанию

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GEN III V8 ENGINE MANAGEMENT
EVAPORATIVE EMISSION CONTROL SYSTEM
The Evaporative Emission Control System (EECS)
captures fuel vapours, which would normally
escape from the fuel tank and enables them to be
consumed in the combustion process. The EECS
is the charcoal canister storage method. This
method transfers fuel vapour from the fuel tank to
an activated carbon (charcoal) storage canister to
hold vapours when the vehicle is not operating.
When the engine is running, the fuel vapour is
purged from the carbon element by intake air flow
and consumed in the normal combustion process.
The fuel tank cap is not vented to atmosphere, but
is fitted with a valve to allow both pressure and
vacuum relief. The canister is a three port design:
The fuel vapour is absorbed by the charcoal in the
canister. When the engine is running, air is drawn
into the canister through the atmospheric port at
the top of the canister assembly. The air mixes with
the vapour and the mixture is drawn into the intake
manifold via the canister purge line. The purge port
on the canister is controlled by a PCM activated
purge solenoid valve. The solenoid valve controls
the manifold vacuum signal from the throttle body.
The vapour inlet port allows fuel vapour to enter
the canister from the fuel tank. The atmospheric
port allows fresh air to be drawn into the canister.
This system has a remote mounted canister purge
control solenoid valve. The PCM supplies a Pulse
Width Modulated (PWM) earth to energise the
solenoid to control vacuum to the canister. The
duty cycle of the PWM signal varies with mass air
flow, intake air temperature and throttle position.
Under cold engine conditions, the solenoid valve is
turned off by the PCM, which blocks vacuum to the
canister and prevents purge.
The PCM turns on the solenoid valve and allows
purge when:
• The engine coolant temperature is below 30°C
at start up.
• The engine has been running for at least two
minutes
OR
• The engine coolant temperature is above 30°C
at start up.
• The engine has been running for at least 30
seconds.
• The engine is not in Decel Fuel Cutoff Mode
• The throttle opening is less than 96%.
• Engine is in Closed Loop or Open Loop Fuel
Mode.
A higher purge rate is used under conditions that
are likely to produce large amounts of vapour,
when the following conditions are met:
• Intake Air Temperature is above 50°C.
OR
• The engine coolant temperature is above
100°C.
• The engine has been running more than 1 5
minutes.
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