Why Is My Car Engine Missing

car engine missI’ve changed all the spark plugs, ignition coil pack in cylinder 3, new injector in cylinder 3 and i still have a cylinder 3 miss fire, what else can I do? Why is this engine missing like this?

Please help!!!

Hi there,

Well, I would check compression on all cylinders, you could have a mechanical missfire like from a valve problem.

If compression is low on that cylinder, you will need to remove the valve cover first and make sure valve springs and push rods etc. are all ok. If ok, then the next step is to remove the cylinder head and send it to a machine shop for a valve job.

Double check for a vacuum leak under the hood first, I have been fooled before!!!

How to check for a vacuum leak

Follow Up

I cleaned the throttle body, all around the engine and cylinders and I just checked for vacuum leak and a PCV hose had a long crack in it, I will replace the hose, could this be the problem? If not , I will check compression,

I really appreciate your help.


Hello again Reggie,

The pcv hose COULD be the issue causing a vacuum leak like I suspected, would be worth repairing first before you spend more time and money. You might want to check for vacuum leaks around the intake manifold as well, with a can of WD40 or propane tank with a rubber hose attached to help you locate the leak. Keep all flammables away from spark plug wires or anything that produces a spark 🙂

Posted in: Running Problems

4 Comments on "Why Is My Car Engine Missing"

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  1. JEFF LUMSDEN says:


    • Austin Davis says:

      It could be possible to set a code, like an oxygen sensor code…a miss fire? hummmmm, probably not show up as a missfire. Although, if the converter is stopped up it can produce sluggishness and lack of power which might be seen as a miss.

      Take your hand with a rag on it, have someone mash down on the gas pedal a few times in park as you put your hand on the exhaust pipe. The engine should rev up quickly, and there should be lots of exhaust coming out the tailpipe. if not, you might have a restriction in the exhaust system that needs to be checked out further.

  2. Terance says:

    Thank you Austin, this was a very helpful article to me. I had changed my spark plugs about 6 months ago and the engine started to miss and run bad on heavy acceleration like going up a hill.

    I thought it was my transmission at first, or a fuel pump but read about spark plug wires on your article and decided to replace mine. That was the problem and never would have guessed that.

    • Austin Davis says:

      Thank you Terance! Yes a bad spark plug wire will usually break down under a heavy load or extreme heat and can give the illusion of a transmission problem. Glad the article was helpful to you. Thanks for your comment.

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