Auxiliary Air Valve System Test
- Engine must be cold to perform test. Install tachometer to engine. See ADJUSTMENTS
article for tachometer attaching points.
- Start engine. Turn idle speed adjusting screw to bottom of its travel. See Fig 1. Engine RPM should drop slightly when coolant temperature is below 176°F (80°C).
- Back out idle adjusting screw. Warm engine to normal operating temperature. Turn idle speed adjusting screw to bottom of its travel. Engine should idle roughly or die as idle speed adjusting screw is seated.
- If engine RPM does not drop during step 2) or 3), check for vacuum leaks after the valve or restricted chamber in auxiliary air valve circuit. Replace valve if defective.
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