I had the misfire symptoms, shaking (both which would go away 30 mins to 1 hr into it running on a cold morning) and check engine light on (that would turn on and off). Replaced the valve cover gaskets, spark plugs and boots as it was very bad but after doing that it now randomly shakes at idle, check engine light still on and now when slowing down my gears slam at 20 MPH and jolts the car as if I had slammed the brakes for a second. You could never hear the car shaking before changing out the gasket and now it is loud and smokey but hoping the smoke is just from the oil that went down the spark plug holes as the oil was pooled up in the wells. It was not smoking at all prior. You can also hear it in the exhaust. No longer has that loss of power sputter with the shaking. What could have happened? Oh and the plugs are the AC Delco double platinum... Could something else be damaged under my spark plugs and oil somehow got into my transmisson?
My car has 122667 miles.
My car has an automatic transmission.
Hi there. What seemed to happen is that the spark plug well was full of engine oil and when you removed the spark plugs, the oil got into the cylinders. Now, if the rings were sealing very well, the oil will stay trapped in the cylinder for a little while. This is what seems to have happened. The engine was vibrating as the oil was burning and preventing the fuel from burning properly. This could have caused a loss of power and coated the cylinders with carbon. I recommend putting a can of sea foam in your fuel tank to help clean up the carbon and oil deposits in the cylinders. For the check engine light being on, it is best to use a code reader and scan the computer for any pending or stored codes. This will give you a starting point for a diagnostic troubleshooting location. If you need further assistance with your engine running rough after changing out the valve cover gaskets, then seek out a professional, such as one from Your Mechanic, to help you.
Hello. Since the check engine light is on I would start by scanning the computer for codes. Those codes would help me to determine what the issue is. If you have a misfire that comes and goes it can be caused by a few things. I would start by checking to see if there is still oil getting into the spark plug holes as that will cause the smoke and the misfire. It may just be a coil that is failing. Once the codes are ready the I could identify which cylinder it is then I could diagnose the issue. You should have a certified mechanic, like one from YourMechanic, check this out to [diagnose why the misfire is occurring] https://www.yourmechanic.com/services/engine-is-misfiring-inspection
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