hi Scotty,
any comments on how to fix a v8 4.6 L 2004 mercury grand marquis with a # 8 coil misfire? 113k miles, p0308 code
ive replaced the coil 3x and it rides good after the initial coil replacement, but then after a period of time check engine light goes on and then low idle occurs, check engine will start to blink and then it drives rough until about 25mph or more then rides great again . As long as im not in stop and go traffic , on the highway the car runs great...not so great in the city.
one mechanic says carbon build up, the other says they need to check for compression, one other says a rebuild engine is the only way.
fyi..
ive replaced the oil with royal purple and added 6 oz of seafoam high mileage to crank case,, im at 500 miles now, still driving rough after the 3rd coil misfire. There also is a vacuum issue, ,when i go up a hill or accelerate the air goes out the defrost and when im stopping, it switches to the vents.. Could this be another issue to aide misfires?
what do you think? How do i get the check engine light off for good . ...heres to hoping smooth riding in the future...
thank you
Well first I would do wet and dry compression test of the engine or have a mechanic. Do it if you don't know how. That'll show off the engines were not. If it is you have no choice but to rebuild it. Now if the pressure is fine then you could have a wiring problem to the coils ot, a computer module problem
