Delawarebear

Showing code P0300 multiple misfire's. 96 Mercury Marquis 4.6 . I have changed all plugs,wire's,air filter, fuel filter and pcv valve..I also swapped out the coil packs but,nothing made any change's. I have raw gas Oder at tail pipe,shudder when shifting into over-drive. She has plenty of power..no hesitation at take off or when I stomp on it..just seems to stumble and misfire when engine speed/rpm's level off.(not under a load) . Could this be the PCU need to be reprogrammed ? Any idea's ?

Bert

Try cleaning the MAF with MAF cleaner. If you unplug it and it runs better, that's where the problem is. Cleaning it may help.

__________________
Bert

Delawarebear

Well.. I got tired of spending time and money so,I bought a code scanner $78's and within 15 minute's I found the problem. Evidently,the person that had the car before me did a tune-up and didn't know what they were doin. Scanner kept ready misfire 2 & 4 So,after everything else I did..there was only one thing left..switched the two plug wires..SO I did.."RUN's LIKE A CHAMP !" Lesson learned always check the firing order and don't just put them back they way you found them. Could have saved a lot of money and head-ache. Now.. I sold the car..made a $600. profit and lookin for a new project. at least I got a new tool to play with out of all this :0)

Bert

Great find. Good luck with your next project.

__________________
Bert