2000 Ford Explorer occassional misfire

cmarcus · Posted at Thu Nov 19, 2009 11:09 am

Engine Performance problem
2000 Ford Explorer 6 cyl Two Wheel Drive Automatic 148000 miles

'00 explorer 4.0 ohv started misfiring cyl 1 after i installed a flowmaster muffler. I thought i could handle it and checked coil, plug, wires, anf uel injectors. everything looked ok, with exception to the coils, cyl 1 was not putting out enough. so i replaced coil pack and cyl 1 plug with a motorcraft plug. mechanic thought it may be a pushrod from me revving it. he did a compression test, said cranking it was 90 and then started it was 0. did a wet test, cyl 1 jumped up. but i dont smoke at all, so i really dont think its rings. he also checked for vaccum leaks. I picked it up from him and surprisingly it runs better, it doesnt misfire as much, yet. however, on occasion is will misfire when i am stops or in a parking lot, etc. but as soon as i drive, maybe 45 seconds it smooths out and stops, even when i come to a stop again. Any help would be appreciated. thank you

racefan966 · Posted at Sat Nov 21, 2009 7:05 am

OK with low compression in that cylinder you will never get that miss to go away untill that is fixed. Now you said it isn't as bad so if you would check that cylinder again for compression. No cylinder should be less then 100 psi anything less indicates a problem and you will have a miss that won't go away either.