Linear Egr Valve Operation And Results Of Incorrect Operation; Egr Pintle Position Sensor; General Description - Positive Crankcase Ventilation (Pcv) System; Crankcase Ventilation System Purpose - Isuzu 1999 RODEO Workshop Manual

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."). The PCM also tests for EGR flow.
If incorrect flow is detected, DTC P0401 will set. If DTC
P0401 is set, refer to the DTC charts.
The linear EGR valve is usually activated under the
following conditions:
f Warm engine operation.
f Above–idle speed.
Too much EGR flow at idle, cruise or cold operation may
cause any of the following conditions to occur:
f Engine stalls after a cold start.
f Engine stalls at idle after deceleration.
f Vehicle surges during cruise.
f Rough idle.
f DTC P0300 (misfire detected).
Too little or no EGR flow may allow combustion
temperatures to get too high. This could cause:
f Spark knock (detonation).
f Engine overheating.
f Emission test failure.
f DTC P0401 (EGR Flow Insufficient detected).
f Poor fuel economy.

EGR Pintle Position Sensor

The PCM monitors the EGR valve pintle position input to
ensure that the valve responds properly to commands
from the PCM and to detect a fault if the pintle position
sensor and control circuits are open or shorted. If the
PCM detects a pintle position signal voltage outside the
normal range of the pintle position sensor, or a signal
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
0017
voltage that is not within a tolerance considered
acceptable for proper EGR system operation, the PCM
will set DTC P0404.
GENERAL DESCRIPTION —
POSITIVE CRANKCASE
VENTILATION (PCV) SYSTEM

Crankcase Ventilation System Purpose

The crankcase ventilation system is used to consume
crankcase vapors in the combustion process instead of
venting them to the atmosphere. Fresh air from the
throttle body is supplied to the crankcase and mixed with
blow–by gases. This mixture is then passed through the
positive crankcase ventilation (PCV) port into the intake
manifold.
While the engine is running, exhaust gases and small
amounts of the fuel/air mixture escape past the piston
rings and enter the crankcase. These gases are mixed
with clean air entering through a tube from the air intake
duct.
During normal, part–throttle operation, the system is
designed to allow crankcase gases to flow through the
PCV valve into the throttle body to be consumed by
normal combustion.
A plugged valve or PCV hose may cause the following
conditions:
f Rough idle.
f Stalling or slow idle speed.
f Oil leaks.
f Sludge in the engine.
A leaking PCV hose would cause:
f Rough idle.
f Stalling.
f High idle speed.
6E1–441
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