Fox 1.8L Digifant II (Federal)
- Ensure engine coolant temperature is at least 176°F (80°C). Ensure A/C system is turned off (if equipped). Start engine and allow it to idle.
- Turn on all electrical loads except A/C system (if equipped). Turn in idle speed adjustment screw until engine speed is 700 RPM. Boost valve I must open and engine speed increase.
- Using throttle, increase engine speed to 1050 RPM. Boost valve I must close and engine speed decrease. If engine speed changes as specified, boost valve I and its circuit is okay. Adjust base idle speed to 860-900 RPM.
- If engine speed does not change as specified, check boost valve relay, ground circuit, and wiring harness for an open circuit. If wiring and ground circuits are okay, replace boost valve I. If wiring harness is okay but ground circuit is not, replace boost valve relay.
- To check idle speed boost valve II (A/C system equipped vehicles only), ensure A/C system is off. Disconnect idle speed boost valve I wiring harness connector. Start engine and allow it to idle.
- Turn A/C system on (engine RPM should increase). With engine idling, disconnect idle speed boost valve II wiring harness connector. Engine speed should decrease. If engine speed does not decrease, check boost valve and its circuit. Replace boost valve if necessary.
NOTE:
With A/C on, voltage is supplied to boost valve (to open valve). With A/C off, voltage is not supplied to boost valve (normally closed). If engine speed does not decrease, ensure boost valve is not stuck open.