# 3cyl misfire changed coil pack still misfires plug wire checks to be good plug is new. what could be the problem?
If # 3 cylinder has spark at the plug it must fire if the following conditions apply. Injector is supplying fuel to the cylinder. and cylinder compression tests OK . So check above ,one or both must be at fault.
SOURCE: engine code p0307 cylinder #7 misfire
It could be carbon deposits on valve seats keeping valves from totally closing. You can try getting you a can of motorcraft PM3 top end engine cleaner and get engine up to operating temp then remove one of the small vacuum lines from the intake and draw the contents of the can slowly into the engine.After you have drawn in the contents shut engine off and let it soak for about 45 minutes then crank it back up and let it run until it clears. Now it will smoke like a forrest fire while you are doing this so don't be alarmed,just tell the neighbors you are spraying for mosqitos.This may cure the problem. If not you may be looking at a valve job.
This can be verified with a compression test if this is what is causing it.
SOURCE: Random Misfire on 2 & 3
I had a problem with a chevy with random misffires on all cylinders. It was the computer. Fords have very few problems with there computers. Does the check engine come on? Maybe have it scanned.
misfire caused by leaking in the intake valve you must chek it , or may be your car is working rich that means fuel - air mixture is not on the right ratio so check your oxygen sensor
SOURCE: 1998 crown vic police. Had check engine light with
your egr on that side is dirty try cleaning it aslo check intake boltsaround those clyinders.
A code P0303 may mean that one or more of the following has happened:
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