Taurus L4-153 2.5L HSC (1986)
Throttle Position Sensor: All Technical Service Bulletins
Engine - Stalls At Idle or During Deceleration
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STALL - AT IDLE OR DURING DECEL - 2.5L HSC
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IDLE - ERRATIC OR HIGH - 2.5L HSC
Article No. 88-2-13
FORD:
1986-87 TAURUS
LINCOLN-MERCURY: 1986-87 SABLE
ISSUE:
Stalls at idle or during decel when the vehicle comes to a stop, or an erratic or high engine idle may be caused by an incorrect setting of the
throttle stop adjusting screw (hard stop), linkage or throttle shaft binding, TV rod adjustment, TP sensor, or 12A581 wiring harness chafing.
ACTION:
To correct this, use the following diagnostic service procedures.
NOTE:
Make sure there are NO SYSTEM VACUUM LEAKS before doing this procedure.
1.
Perform EEC IV Self-Test. During Self-Test make sure the ISC motor is operating correctly. If service codes are present, refer to the
Engine/Emission Diagnosis Manual, Volume H, Section 16 for service information. If no service codes are present, go to Step 2.
2.
With engine off, check if there is any chafing or damage to the engine wire harness (12A581). Special attention should be given to the area of the
ground strap attaching bolt located at rear of intake manifold. If chafing is present, refer to TSB article 87-17-3 for repairs, and continue with Step
3. If there is no chafing, go to Step 4.
3.
If symptom is corrected, stop here. If symptom is still present continue with Step 4.
4.
Make sure throttle shaft is free, that travel is not obstructed, and cruise control (if equipped) is not holding throttle open.
a.
Idle engine at normal operating temperature. Check to make sure throttle lever is in contact with ISC motor.
b.
If contact is obvious and idle RPM drops to correct "curb idle" RPM with slight pressure, a sticking or binding condition is indicated. With
engine off, determine cause of sticking or binding. Disconnect the TV linkage (ATX only), cruise control cable (if equipped), and throttle
cable. If idle speed has not returned to correct "curb idle" RPM, the tracking switch has failed or throttle shaft is binding because of swelled
end seals or a bent throttle shaft. Fully retract and disconnect the ISC motor (see below - retract ISC motor). If throttle does NOT return to
hard stop position, replace throttle body. RELEARN IDLE (Step 8). If symptom is corrected, stop here. If throttle did return to the hard stop
position, go to Step 5.
FIGURE 21
RETRACT ISC MOTOR
With engine "OFF", remove air cleaner. Connect a jumper wire between Self-Test input connector and signal return pin on the self-test connector,
Figure 21.
