Q: Engine is misfiring and the service engine soon light is on.

asked by on February 11, 2017

My van is missing, especially worse when on load, less when idling. Brought it to a mechanic who diagnosed that cylinder "6" is the problem. He didn't change or fix the problem, said I needed to have several " gaskets " replaced as oil is leaking on the coils and spark plugs of " ALL " cylinders but worse on the "6". Said I have to spend $700-$800 to replace all said gaskets and fix things. Said its quite useless for him to do anything on the "6" alone as whatever he does would soon be messed by all the oil splashing.

I am wondering if this is close to the truth, or just a ruse to squeeze money from me.

My car has 248920 miles.
My car has an automatic transmission.

Hi there.

If the engine is misfiring you would need to check the spark plugs and fuel injectors to see what is not working. If the spark plug has no spark, then check the spark plug wire for spark by-passing the spark plug with a spark tool. If there is spark, then the spark plugs are not working and need replaced. If the spark plugs are firing, then there could be an issue with the fuel injectors causing the engine to run rough and misfire. Remove one harness to each injector at a time (one at a time) and see if the engine stumbles more. If the engine stumbles more, then the fuel injector is working. If there is no change, then the fuel injector is not working and would need replaced. If the fuel injectors and spark plugs are working properly, then there could be an issue with the cylinder. Then you could take a compression tester and check all of the cylinders and compare the reading. They all should be about the same. If number 6 is lower than the rest, then there could be an issue with the head gasket, a burned or sticking valve, or the piston rings are worn causing a low compression. A leak down tester (requires compressed air) will determine the cause and location of a low cylinder compression. If the mechanic did not perform these tasks to determine the expensive repair, then I recommend seeking out a professional, such as one from Your Mechanic, to help you.

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