Rough Idle/Engine Stalls at Idle — Before Warm-up (continued)
F2-36flowchartRough Idle/Engine Stalls at Idle — Before Warm-up (steps 6-9)
1
STEP 6: Is engine coolant temperature sensor resistance correct? (page F2-152) (See resistance vs coolant temperature graph)
No
Replace engine coolant temperature sensor
Yes: Go to next step
2
STEP 7: Connect System Selector to data link connector and set Test Switch to "SELF TEST" when engine is cold. Does engine speed decrease as engine warms up?
No
Check air valve (page F2-99)
Yes: Go to next step
3
STEP 8: Connect System Selector to data link connector and set Test Switch to "SELF TEST"; is ignition timing at idle correct after warm-up? (page F2-70) Ignition timing (BTDC): 9—11° {10 ± 1°}
No
Adjust ignition timing (page F2-70)
Yes: Go to next step
4
STEP 9: Try a known good ECM; does condition improve? (page F2-141)
No
Change to another brand of fuel
Yes
5
Replace ECM (page F2-141)