90-823225--1 10965E-130 - ELECTRONIC FUEL INJECTION (MULTI-PORT AND THROTTLE BODY)
ROUGH, UNSTABLE, OR INCORRECT IDLE,
STALLING
(continued)
CHECK SENSORS AND CONTROLS FOR:
1. Proper Idle Air Control (IAC) operation.
2. Possible open the in following circuits for CKTs 410, 417, 416, 813 and 814.
3. Possible short to ground in CKT 417, Throttle Position (TP) sensor signal, CKT 416 Throttle
Position (TP) sensor 5 volt reference and CKT 451 diagnostic test circuit.
4. A sticking throttle shaft, binding linkage or salt corrosion will cause a high Throttle Position (TP)
sensor voltage (open throttle indication), the ECM will not control idle. Using a scan tool or volt-
meter record Throttle Position (TP) sensor voltage. It should read approximately .7 volt closed
throttle and approximately 4.5 volts at Wide Open Throttle (WOT).
CHECK ENGINE FOR:
1. Proper cylinder compression.
2. Proper camshaft or weak valve springs.
ADDITIONAL CHECKS:
1. Sticking or binding throttle linkage and salt corrosion.
2. Proper alternator output voltage.
3. Battery cables and ground straps should be clean and secure. Erratic voltage will cause Idle Air
Control (IAC) to change its position, resulting in poor idle quality.
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