QuestionQUESTION: My Mazda was vibrating/pulsating on idle, especially when at stop lights. I also noticed a slight vibration at around 40 mph but when i accelerate, it goes away.
I was told to replace the Valve cover gasket since it was leaking. I did replace the gasket, and also replaced spark plugs and the spark plug cables. Mehcanic told me that the car still had a slight vibration at idle but that it should go away since there was some oil that had leaked into the cylinders and eventually burn off.
However, after driving around a few times over the last few days, the vibration has not gone away and is still behaving similarly as before, but not as bad. I can drive on the highway and cruise at 60-70 mph normally, and acceleration is ok. The check engline light came on too. I am not sure what it could be, but after looking onlune at various comments, it looks like it could either be the PCV, distributor or CV joints. It could also be a vacuum leak. Any advice or tips would be really helpful before I take this car back for repairs so that I know what to pinpoint. Thanks
ANSWER: Sounds like a coil may be failing, check for spark to each plug.
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QUESTION: Is the coil easy to check on my own, or would I need to get a mechanic to look at it ? As i mentioned, the plugs are brand new, would the coil affect the plug or is it a separate part ?
Thanks
AnswerThat engine should have six direct fire coils located on top of each spark plug. Each one has a harness that leads to it. If you unplug the harnesses one at a time and note the change it has on the engine speed then you should be able to "field test" it yourself. The one with the least effect on the engine idle quality is most likely the bad one, disconnecting good ones will most likely induce a heavy misfire. Coil/boot assemblies run about $125 each. You have six.
