How much does it cost to fix a misfiring cylinder?

My check engine light came on so a friend ran some diagnostics and found out that a cylinder is misfiring. I have a 2007 Ford F-150 and he said that a spark plug broke off into the cylinder. He doesn’t have the tools to fix it so I was also wondering if i need to go to te Ford dealership or would any mechanic do it.

10 Answers

  • Ouch, spark plugs don’t typically don’t break. More often than not someone tries to remove it to check it and the carbon build-up on the exposed spark plug threads inside the combustion chamber are too gummed up and it seizes in the head, snapping off. Typically it’s someone trying to check the plug that broke it.

    If the plug is broken off then it depends on how it’s broken as to what repairs are needed, if it’s seized in the head then you are going to want a professional to handle it else you’re likely to end up with a damaged head.

    Once that problem is solved re-check the system, a missfire can be cause by a LOT of stuff… plugs/wires/injectors/compression loss/coil pack/etc, it’s not like it was 40 years ago where plugs/wires/cap/rotor/condenser solved all.

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    RE:

    How much does it cost to fix a misfiring cylinder?

    My check engine light came on so a friend ran some diagnostics and found out that a cylinder is misfiring. I have a 2007 Ford F-150 and he said that a spark plug broke off into the cylinder. He doesn’t have the tools to fix it so I was also wondering if i need to go to te Ford dealership or…

  • https://shorturl.im/jIqpP

    You have the 5.4l which has an extended plug that does break off in the plug hole but can be removed with an extraction kit. This engine is famous for this problem. A dealer should be best equipped for the job as they must see thousands of them. The Labor to do this job is expensive and the plugs are a special design that are also a lot of money but not nearly as much as pulling the heads. I would expect a 500 dollar bill.

  • I could imagine a bad spark plug. And I could imagine a broken spark plug. But I wonder about a spark plug that is broke off inside the cylinder.

    I would be very suspicious of this friend. I am synical enough to think he may have broken the spark plug off, (but not inside the cylinder.) while trying to remove it with the wrong wrench

    Any mechanic should be able to do the job. But I think your friend was not the help that he wanted to be.

  • I seriously doubt if the plug is inside the cylinder. It probably broke off at the threads. It sounds like you aren’t real knowledgeble about motors so I would suggest a reputable repair shop. The dealer will charge you about 3 times what a shop would.

  • That depends on the level of damage, and how the plug broke off. This is actually fairly common with this engine, but I’m wondering who actually broke it? I’d suggest going either to Ford or to a shop that has specific experience with this. Expect to pay $2-300, or a lot more if the head has to come off.

  • They are known for that. A good independent repair shop should charge you alot less than going to a dealer. There is a tool available to extract the broken spark plug on those engines.

  • As D and shorty say, it is a common problem with those heads. The guys I know with late model Ford trucks remove their spark plugs every few years and reinstall them to prevent them from seizing badly. I agree with D (best answer) that the experience of Ford mechanics will make them the best value.

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