Engine - Fast Idle Remains On After Warm-Up
86ford21 Article No. 86-6-15FAST IDLE - 5.0L CFI - REMAINS ON AFTER WARM-UP
FAST IDLE - 5.0L CFI - COMES ON WHILE DRIVING
FORD 1984-85 CROWN VICTORIA, THUNDERBIRD, LTD
LINCOLN-MERCURY 1984-85 GRAND MARQUIS, COUGAR, MARQUIS, CONTINENTAL, MARK VII, LINCOLN
Excessive resistance in the choke circuit can cause high engine idle speeds.
High resistance due to variations in choke cap or poor connections in the choke feed wire, or loose choke cap screws can result in loss of heat in the choke. If this occurs, the fast idle cam is moved to the "high idle" (cold) position. The engine may remain in the fast idle mode after engine becomes warm. Also, because the condition can be intermittent, the engine idle rpm may randomly change to fast (cold) idle during driving maneuvers after the engine temperature is stabilized.
If the choke cap remains cold to the touch following 20-second warm-up period, there may be an intermittent high resistance in the choke circuit.
1. Verify that the choke cap attaching screws are firmly set.
2. Perform the Cap Continuity Test.
3. Replace choke cap or wire feed as required.
4. Confirm that the cap gets warm within 20 seconds after restart.
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Reimbursable within the provisions of the Warranty and Policy Manual.
OPERATION: SP9848A86 - Test system - Replace choke cap.
TIME: 0.4 Hr.
OPERATION: SP9848B86 - Test system - Replace wire terminal.
TIME: 0.4 Hr. DLR. CODING: Basic Part No. 9848 - Code: N5
III. Cap Continuity Test
A. Connect an ammeter in series with the thermostat housing terminal and the electrical lead joining to the thermostat housing.
B. Start the engine. The ammeter should indicate a surge of current and then register 2-amps or less after 20-seconds.
1. If there is a steady current draw of more than 1.0-amps after 60-seconds, replace the thermostat housing, refer to Shop Manual, Group 24.
2. If there is no current draw, connect a jumper wire from the ammeter lead to the center tap of the alternator. If the current draw is to specification, replace the feed wire; if not, replace the thermostat housing, refer to Shop Manual Group 24.