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Q: Car shaking and misfiring

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My car is shaking. The mechanic I took it to said it was misfiring. I had the spark plugs changed and now it is driving worse than it was before.

A: Hi. The first thing to do is check the code...

Hi. The first thing to do is check the codes stored in the engine computer. If the engine is indeed misfiring, codes will be stored. The source of the misfire will need to be identified, possible faults include a failing fuel injector, ignition coil, engine computer, etc. However, there are quite a few TSB's (Technical Service Bulletins) that address a whole host of power/drivability issues stating updated software for both the engine computer and transmission computer. Incorrect fuel maps before and after turbo kicks in or faulty torque converter lockup logic maps may be the cause of your concerns. You may want to enlist the help of a mechanic, like one from YourMechanic, to read out faults and diagnose the misfiring issue your vehicle is encountering.

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