Cylinder 8 Misfire Detected

A misfire in cylinder 8 means that the engine is not firing properly in that cylinder, which can cause rough running and increase emissions.

The engine control module (ECM) sees that cylinder 8 is not producing the expected power output during the combustion cycle, as indicated by fluctuations in crankshaft position sensor signals or differences in RPM.

Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.

1. 11. Check for visible damage to wires and connectors leading to the ignition system of cylinder 8. If damaged, repair or replace them. Decision: If repaired, clear codes and test drive.
2. 22. Inspect the spark plug in cylinder 8 for wear or damage. Replace if worn. Decision: If replaced, clear codes and test drive.
3. 33. Swap the ignition coil from cylinder 8 with a known good cylinder (e.g., cylinder 7 or 6). Clear codes and test drive. Decision: If code follows to the new cylinder, replace the ignition coil.
4. 44. Check fuel pressure with a gauge; it should be between 30-50 PSI at idle. If low, check fuel pump operation and fuel filter conditions. Decision: If fuel pressure is insufficient, repair fuel system.
5. 55. Inspect intake manifold and vacuum hoses for leaks; use propane to detect any leaks around cylinder 8. Decision: If leaks found, repair the vacuum leak.

• Faulty spark plug
• Defective ignition coil
• Low fuel pressure
• Vacuum leak at or near cylinder 8
• Exhaust valve issue in cylinder 8

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