Camaro V8-305 5.0L VIN E TBI (1989)
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Check AIR management system for intermittent air to ports while in "Closed Loop".
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In addition to electrical control of EGR, be sure to examine the EGR valve for proper seating.
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Faulty battery cables can result in voltage variations. The ECM will try to compensate, which results in erratic idle speeds.
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The ECM will compensate for A/C compressor clutch loads. Loss of this signal would be most apparent in neutral.
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Contaminated fuel can adversely affect idle. Perform injector balance test CHART C-2A.
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If all OK, refer to TESTING PROCEDURES/DIAGNOSIS BY SYMPTOM/STALLS-ROUGH,UNSTABLE OR INCORRECT IDLE.
Idle Air Control Valve (IAC) Reset Procedure
To reset the Idle Air Control (IAC) valve pintle position, proceed with the following:
1.
Block the drive wheels, and apply the parking brake.
2.
Start the engine, and hold the engine speed above 2000 rpm. Ground the diagnostic test terminal (ALDL) for ten seconds, then remove the ground.
3.
Turn the ignition "OFF," then restart the engine and check for the proper idle operation.
The Idle Air Control (IAC) valve may also be reset by the ECM when the vehicle is driven at a speed above 40 mph. Ignition may have to be cycled
"OFF" and "ON" a few times before proper idle can be obtained.
