Air Flow Meter
Function of pump contacts
Deflect meter flap slightly.
Measure the resistance between terminals 36 and 39 on the air flow meter.
The resistance should fall from infinite resistance (flap closed) to 0 Ohms (flap slightly open). If no transition from infinity to zero, replace air flow meter.
Adjusting exhaust gas CO level
Using the bypass air screw in the air flow meter to adjust idle mixture, set the CO to 1.5-2.5% with the engine at normal operating temperature.
Adjusting idle speed
With the engine at normal operating temperature, set the idle speed with the bypass screw on the throttle housing.
412 with manual transmission: 800-900 rpm
412 with automatic transmission: 900-1000 rpm