Random Multiple Misfire

[DeuceX]

I've read and reread everything I can find on diagnosing and fixing misfires, but to no avail. I've got new plugs, wires, coil packs, and a new ignition control module. New serpentine belt, new fuel filter. Cleaned out the fuel system and crank with seafoam. Nothing works.

However, when I first bought the car, it had a slight miss that began to get worse. That was when I replaced the plugs and plug wires. At the time, it fixed the problem...and it stayed fixed for a couple weeks. Recently, however, its come back and its worse than ever. I'm at wit's end, and the only thing I can think of is either the PCM is bad, or the plug wires got melted. A mechanic in my unit said there was a sensor on the back of the engine block that went bad, causing his car to do the same as mine. Can't remember what he had, but it had the 3800 in it.

As for the misfire itself, it went from appearing at WOT, to appearing when going up a hill, to being a constant thing.

Any help is appreciated.

[Black98Fivespeed]

Re: Random Multiple Misfire

cam or crank position sensor. See if you can get your hands on a good (really good) scanner and see if you can narrow down which cylinders are misfiring. If it's all the cylinders, there's a good chance it's a sensor or a timing issue. If it's just a couple, go back over what could be causing JUST THOSE cylinders to misfire (plugs, wires, coils, etc.). I had the same problem a while back. Those random/multiple cylinder misfire codes are a pain, mostly because it doesn't discern between a random and multiple cylinder misfire!

[DeuceX]

Re: Random Multiple Misfire

Thanks. I'll try to run down to the stealership tomorrow and see if they'll hook it up free of charge. From what I was told, its a really simple change if it is the crank position sensor. Just a simple one bolt deal.

[3.4orNothing]

Re: Random Multiple Misfire

Thanks. I'll try to run down to the stealership tomorrow and see if they'll hook it up free of charge. From what I was told, its a really simple change if it is the crank position sensor. Just a simple one bolt deal.

hahahahahahaha STEALERSHIP,,,HAHAHAH THATS A GOOD ONE!!


ANYWAYS,i still think that it is wires,or coils,,,electric parts can go bad in 10 years or 1 day....good luck.

[Meatyshells]

Re: Random Multiple Misfire

i had that problem, turns out some of my spark plug wires were getting to hot and melting

[95redslp]

Re: Random Multiple Misfire

i would check otu the crank sensor... it should be sending a code like... ignition problem loss of 24x signal or something like that

[96silverbullet]

Re: Random Multiple Misfire

had the same problem and it was my catalytic converter! got it replaced and it runs better than ever

[DeuceX]

Re: Random Multiple Misfire

Bought a new high flow cat about a month ago, but I suppose that the misfire problem I had could have caused the cat to go bad and compound the problem. I bought a new crank sensor, and the car's at the shop now. They're installing the sensor (cause I don't have the time nor inclination), and they're gonna check all the plug wires. If the plug wires melted, I'm going to make the shop replace the bad ones free of charge, since they are the ones that installed the plug wires ;) Here's hoping, I should know by tomorrow.

[3.8L Strong]

Re: Random Multiple Misfire

Did they find out what was causing the Random Misfire code?

[DeuceX]

Re: Random Multiple Misfire

They said they thought it was the driver in the PCM, so I ordered a new computer from PCMforless.com. I was planning on getting one anyway, since you can't program the 96 PCMs. Hopefully it'll fix everything :)

If not...Iunno >.>

[DeuceX]

Re: Random Multiple Misfire

PCM hasn't gotten here yet...:(

[3.8L Strong]

Re: Random Multiple Misfire

Have you received the new PCM yet? If yes, has that resolved the misfires?

[TheGr8Schlotzky]

Re: Random Multiple Misfire

PCM hasn't gotten here yet...:(

Have you received the new PCM yet?

posted several hours apart...

But keep us updated, I've got a buddy with the same problem, he has replaced just about everything there is to replace, and I'll mention this to him if it fixes your problem.

[DeuceX]

Re: Random Multiple Misfire

PCM fixed part of the problem. I no longer have a Random Multiple Misfire...instead, I have no fire on cylinders 2 and 5. Same coilpack, but the coilpack's good. Replaced it again just to make sure. Thought I might have a bad ICM, but the mech said it was good. Only thing I can think of now is a wire went bad somewhere in the wiring harness, because there's apparently no signal between the computer and cylinders 2 + 5. We did think it could be a fuel problem, but we retested and there is no spark off the coil pack.

Any ideas? I stopped by the shop this morning to have them check the wiring harness this morning. I won't know about that 'til tomorrow, cause I'm gonna be heading into work in a couple hours and I wanna watch Live Free or Die Hard :D

[DeuceX]

Re: Random Multiple Misfire

They told me to take my car to the dealer, cause they couldn't fix it...-_- So, I did. *sighs* Time to spend more money than I should have to :D