Workshop Manual

6E–588
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
The system checks for conditions that cause the EVAP
system to purge continuously by commanding the EVAP
vent solenoid “ON” and the EVAP purge solenoid “OFF”
(EVAP vent solenoid “CLOSED,” EVAP purge PWM
“0%”). If fuel tank vacuum level increases during the test,
a continuous purge flow condition is indicated, which will
set a DTC P1441. This can be cause by the following
conditions:
B EVAP purge solenoid leaking
B EVAP purge and engine vacuum lines switched at the
EVAP purge solenoid
B EVAP purge solenoid driver circuit grounded
Fuel vapor recovery system
060R100095
Separator attaches after hose evaporative fuel. It
protects EVAP Canister from liquid fuel. It guarantees
EVAP Canister performance. When vibration bounces
fuel level, liquid fuel will accrete to EVAP Canister. It
separates liquid fuel.
General Description (Exhaust Gas
Recirculation (EGR) System)
EGR Purpose
The exhaust gas recirculation (EGR) system is use to
reduce emission levels of oxides of nitrogen (NOx). NOx
emission levels are caused by a high combustion
temperature. The EGR system lowers the NOx emission
levels by decreasing the combustion temperature.
057RW002
Linear EGR Valve
The main element of the system is the linear EGR valve.
The EGR valve feeds small amounts of exhaust gas back
into the combustion chamber. The fuel/air mixture will be
diluted and combustion temperatures reduced.
Linear EGR Control
The PCM monitors the EGR actual positron and adjusts
the pintle position accordingly. The uses information from
the following sensors to control the pintle position:
B Engine coolant temperature (ECT) sensor.
B Throttle position (TP) sensor.
B Mass air flow (MAF) sensor.
Linear EGR Valve Operation and Results
of Incorrect Operation
The linear EGR valve is designed to accurately supply
EGR to the engine independent of intake manifold
vacuum. The valve controls EGR flow from the exhaust
to the intake manifold through an orifice with a PCM
controlled pintle. During operation, the PCM controls
pintle position by monitoring the pintle position feedback
signal. The feedback signal can be monitored with a Tech
2 as “Actual EGR Pos.” “Actual EGR Pos.” should always
be near the commanded EGR position (”Desired EGR
Pos.”). If a problem with the EGR system will not allow the
PCM to control the pintle position properly, DTC P1406
will set. The PCM also tests for EGR flow. If incorrect flow
is detected, DTC P0401 will set. If DTCs P0401 and/or
P1406 are set, refer to the DTC charts.
The linear EGR valve is usually activated under the
following conditions:
B Warm engine operation.
B Above-idle speed.
Too much EGR flow at idle, cruise or cold operation may
cause any of the following conditions to occur:
B Engine stalls after a cold start.
B Engine stalls at idle after deceleration.