PROBLEM | POSSIBLE CAUSES | SOLUTIONS & TEST POINTS |
| A spark plug, coil or coil pack may not be working. | Switch the spark plug, coils or coil packs between cylinders and check if the misfire follows the suspicious component. Coil packs tend to go bad, especially on BMWs, and they need to be replaced. |
One or more injectors are not working | Check the injectors while cranking to see if they are working with a noid light. You can also switch injectors between cylinders and check if the misfire follows the suspicious injector | |
Broken, short-circuited, dirty or corroded Control Unit harness connectors causing bad contacts. | Ensure all the Control Unit harness connectors are not broken or have a short-circuit problem. Also, clean any rust or corrosion. Ensure tight fit. | |
No compression in the cylinders of the engine | Perform a compression check on all the cylinders. | |
Engine or Distributor timing is off | Ensure that the timing is correctly set. |
| WARNING Some of the testing procedures described in this guide could be dangerous if done improperly. We recommend that they are performed by an ASE certified mechanic |
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