- Clamp the air injection hose below the relief valve.
- Connect a tachometer to the engine.
- Start the engine and allow it to reach normal operating temperature.
- Turn the flowmeter bypass screw all the way shut.
- Adjust the throttle plate housing screw to give an idle speed of 850 rpm (1975) or 900 rpm (1976 and later).
- Turn the flowmeter bypass screw out to produce a 50 rpm drop in the idle speed.
- Remove the clamp from the air injection tube idle speed should stabilize at 800-900 rpm for 1975 models, or 850-950 rpm for 1976 and later models. If not, turn the throttle plate housing screw until it is.
- Start the engine and run it to normal operating temperature.
- Connect a tachometer to diagnostic connectors D1-1 and D1-3.
- Turn all accessories off.
- Wait for the electric fan to cycle on, then off.
- With the fan off, adjust the throttle bypass screw to establish the idle at 600-700 rpm with the transmission in neutral (MT) or Drive (AT).