Q: misfire and high idle when hot

asked by on April 26, 2016

so I replaced a blown head gasget and now I know I timed it correctly but I put it back together and now I am getting check engine code p0300,p0301,p0303 when hot and cold the code goes away when hot I see white smoke out of the muffler and it smells of burnt oil and idles at 2000rpms and has a missing fire sound after I gun it for a bit. when warm or cold no misfire and 800rpm idle. I checked the pcv valve and it is fine. its not getting hot. idk what to do? thanks

My car has 207000 miles.
My car has an automatic transmission.

You should have a compression test and cylinder leakage check done on the engine to see if one or more cylinders have low compression, or is leaking compression somewhere. Check that all of the spark plug wires and injector wires are put on to the correct cylinders. Since the problem is with cylinder numbers 1 and 3 it’s possible that you have the wires crossed.

Did you replace the oil and filter after the head gasket was replaced? If the rings are stuck or sticking it would explain the engine running better after revving a couple of times. A certified mechanic can inspect your vehicle to diagnose your Check Engine Light codes and find the right fix for your misfire.

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