Diagnostic Aids
WARNING: This page is about a different variant/trim than selected.
- A misfire DTC could be caused by an excessive vibration from sources other than the engine. Inspect for the following possible sources:
- A tire or wheel that is out of round or out of balance
- Variable thickness brake rotors
- An unbalanced drive shaft
- Certain rough road conditions
- A damaged accessory drive component or belt
- The scan tool data parameters Engine Speed at Misfire and Load at Misfire are populated and frozen at the time the MIL illuminates. These scan tool displays can be used like additional lines of Freeze Frame data. Review the information located in the Engine Speed at Misfire and the Load at Misfire scan tool parameters. The information can help determine engine operation when the misfire occurred.
- An intermittent can also be the result of a defective CKP sensor signal rotor. Remove the CKP sensor and inspect the signal rotor through the sensor hole. Check the condition of the signal rotor for nicks, dents, missing teeth, and foreign material. Refer to Crankshaft Position Sensor Replacement .
- An MAF sensor output that is incorrect may cause the PCM to command the fuel system to go lean. Check the performance of the MAF sensor. If the heated oxygen sensor (HO2S) voltage is fixed low, while the fuel trim is constantly high, check the MAF sensor signal circuit for resistance. High circuit resistance can cause the sensor to read a lower volume of air than actual, resulting in a lean fueling condition that can cause engine misfire.
- Use the scan tool to perform a cylinder balance test by commanding individual fuel injectors OFF with the engine running - Refer to Powertrain Control Module Scan Tool Information .
- High resistance in the circuits of the injectors could set a misfire DTC. Test the injector circuits of the affected cylinder(s) for a high resistance if you suspect a condition.