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Home >> Chevrolet >> 1998 >> Astro Van 2WD V6-4.3L VIN W >> Repair and Diagnosis >> Powertrain Management >> Tune-up and Engine Performance Checks >> Idle Speed >> Testing and Inspection
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Idle Speed: Testing and Inspection

IDLE SPEED
- When there is a problem with the idle refer to Diagnostic Tables / System Diagnostic Tables / Idle Air Control System Diagnosis. Testing and Inspection

- System too lean (High air/fuel ratio)-Idle speed may be too high or too low. Engine speed may vary up and down, disconnecting the IAC valve has no effect.

- System too rich (Low air/fuel ratio)-idle speed too low. Scan counts usually above 80. System obviously rich and may exhibit black exhaust smoke. Scan tool and/or voltmeter will read a Heated Oxygen Sensor (HO2S) signal fixed above 800 mV (0.8V).
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