My Car Is Shaking After Putting New Spark Plugs In What Could Be Wrong

Posted in Ignition Systems | Asked on May 20, 2010

I just replaced the spark plugs on a 2002 Merc Cougar, just a 4cly 2.0, and now the car is shaking, I know that I did everything right, and there is nothing wrong with the car, so what did I do wrong with putting the new spark plugs in?

There are 11 Answers for "My Car Is Shaking After Putting New Spark Plugs In What Could Be Wrong"

  1. Patrick Z says:

    two of the plug wires are reversed…

  2. ? says:

    If you got the wires on the wrong plug your cylinders are firing out of order. The shaking engine is a typical sign. Lots of people make this mistake.

  3. dc says:

    sounds like one of the spark plug wires may not be fully connected to the spark plug. remove and replace the wires making sure they are fully seated on the plugs

  4. shazam 88 says:

    You probably crossed two of the wires over..Easy to do, I,ve done it myself without knowing

  5. letmeknow says:

    4 cyl’s run real smooth so maybe you accidentally disconnected a vacuum hose. Double check your spark plug gap and make sure your wires aren’t frayed. Good luck.

  6. BrettH8sU says:

    Incorrect instalation of plugs, plug wire not on all the way or damaged or grounding out or incorrectly routed, coil going out. If you rev up the engine the check engine light should come on for an engine misfire code. (its a newer car, if you try pulling the plugwire off it may ground out through the computer and fry it, that trick should only be done on older car without electronic ignitions)

  7. Cletoman says:

    Check the wires, you might have crossed them. Then if that doesn’t work check the gap on the plugs. or you might have a vacuum leak.

  8. ? says:

    Pull the plug wires off one at a time. If it doesn’t make the engine worse, you know you pulled off the one that the trouble. You could have a bad gap because you hit the electrode when you put the plug in. You could have a bad connection at either end of the wire. A new plug could be bad. A plug could be loose. You could have hit some crud and plugged up the gap in a plug.

  9. Mr. Cool says:

    Double check the firing order to make sure the wires are routed to the correct cylinders. If that checks out, pull the plugs back out and inspect them closely; its possible you may have cracked the porcelain on one of them when you installed them.

  10. baldie says:

    did you adjust the gap first? even though they say they are factory adjusted, don,t go by that, adjust them first, or you happened to crack 1 putting them in, it,s possible if the rubber insert isn,t in the socket. you also could have a couple wires backwards, check your firing order.

  11. dirtytricksracing@sbcglobal.net says:

    Plug wires not right.