P1398

Tests 516 - 521:

SYMPTOM
P-1398 MISFIRE ADAPTIVE NUMERATOR AT LIMIT

WHEN MONITORED
Under closed throttle deceleration Eng coolant temp > 176 deg, and > 50 seconds after engine start. Speed at which deceleration occurs must be sufficient for given gear range, e.g., > 36 mph in 1st gear or > 65 mph in high gear. Injector PW must be zero.

SET CONDITION
One of the crankshaft position sensor target windows has more than a 2% variance from the reference window.

POSSIBLE CAUSES
- Adaptive numerator will not re-learn
- Crankshaft position sensor defective
- Flexplate observable defect
- CKP sensor connector observable defect
- CKP sensor connector observable defect