Sicking missfire that won`t go away

[mark a]

totally disgusted.... just changed LIM gasket put new plugs new wires,installed a PCM from intense also a aeroforce scanguage . A while back I gutted my airbox which I already had the K&N filter in it. Also a 180 degree thermostat. I almost forgot, there`s also a 3.something smaller SC pulley on it. Now I have a missfire on number 4 cylinder. the car is running really bad! So I changed #4 plug and wire swapped coils with one from a non misfireing cylinder. I looked for any wires or vacume lines I may have overlooked on rebuild from the LIM. I`ve been going nuts! There`s also no codes except the one for missfire , I think it is PO3OO or something close to that. Any suggestions? Has anyone had this problem? I so want to run this car at WOT to see what it will do! thanks for listening. hope to hear from someone soon. Hopefully with the answer, ha ha .

[00Beast]

I'd get a good ICM and swap it in. I chased the same issue for a few weeks, ended up being a coil, but my aeroforce showed the wrong cylinders misfiring. The code should be P0304, the code is matched to the misfiring cylinder. Cyl 4 misfire is P0304, 5 is P0305, etc. If it is P0300, then the computer cannot tell which is misfiring, it just knows that there is a misfire.

[mark a]

Thank you for the suggestion.







Thanks for the heads up. It ended up that I checked the coils with an ohm meter. Found a few bad primary readings. Decided to just get all three. After installing them decided to change out the #4 injector ,just had a feeling it might be clogged. I ended up finding the fiber washer on the end of the injector was in pieces. I had a spare injector to put in, but I sucked out any small pieces around the edge of the hole with my shop vac. Seemed that the combination of things worked, running great now. Went out and checked it out with a few good WOT runs. So far so good ! Thanks again for the help!

[00Beast]

No problem. I had a similar issue with my car when we did LIM gaskets, except that my fiber washer disappeared, and the o-ring tore as it was going in, causing a huge vacuum leak. Car idled like crap till we discovered that and fixed it.

[dwight]

I'm having the same problem. It says random/multiple misfire. Did replacing the coil actually fix it. I'm asking before i go and buy a coil and how much does a coil cost. Thanks! Dwight

[willwren]

dwight, your problem may very likely be a totally different solution. It would be best to start your own topic so we can help. Start your topic by telling us the age and brand of your plugs as well as your wires.