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Other Causes Of Misfires
So you tested the four spark plug wires (per the instructions in TEST 1) and they all sparked, but your Cavalier (or Sunfire) still suffers a misfire problem. Well, here are a few suggestions that may inspire your next round of tests:
- The valve cover gaskets are leaking oil onto the spark plug wells and soaking the spark plugs and spark plug wire boots in oil.
- Over time, this oil will cause a misfire as the oil cooks and turns into carbon tracks.
- The photos in the image viewer show you what a carbon track looks like on the inside of the spark plug wire boot and on the ceramic insulator of the spark plug.
- Engine compression test.
- One of the most overlooked diagnostic tests to find the root cause of misfire is the compression test.
- You'll need an engine compression tester of course.
- The engine compression readings between cylinders should not vary more 15%.
- I've written a step-by-step 2.2L GM compression test tutorial you can find here: How To Do An Engine Compression Test (GM 2.0L, 2.2L, 2.5L) (at troubleshootmyvehicle.com).
- A bad fuel injector.
- A fuel injector can go bad and not set a specific fuel injector code.
- The fuel injectors can be tested with a simple fuel injector resistance test, and you can find this test here: How To Test The Fuel Injectors With A Multimeter (GM 2.2L) (at troubleshootmyvehicle.com).
- Carbon tracks on the spark plug(s) and in the inside of the spark plug wires.
- The orange arrows in the photo above point to what carbon tracks look like.
- It's not possible to clean a carbon track. You can scrape and clean, but it won't go away. Replace the components affected with carbon tracks and this usually means both the spark plug and the Wire together.
- Broken spark plugs.
- This usually happens at tune-up time, if you have dropped one on the floor.
- You power washed the engine, this is something that should be avoided on any vehicle.
If this info saved the day, buy me a beer!
