Help me diagnose a misfire problem.

[Ted]

Ok, first I know I have a misfire somewhere because the SES code on my car is P0300 Engine Misfire Detected or some bullcrap. The first step I took was to get a mechanic to run a cylinder test on my car and it showed that Cyl #3 was misfiring under load. So I changed the plug on cyl #3 even though it was as good as the day I put it in. The wire looked ok. It didn't misfire for a day until it came back. Which lead me to beleive that it could be a coil pack since the code wasn't cylinder specific. And the crappy aftermarket one in there had corroded posts. So I just replaced all 3 of my coil packs and the misfire is still there. It only happens if I give it gas more then 2500rpm. I guess my next step should be to replace all the plugs and wires again? They have under 10k on them so they should be fine. Theres only 3 things that CAN cause a misfire right? Plugs, Wires, and Coils? So what am I missing here?

[Tyler]

plugs, wires, coils, ICM, injectors, stuck valve, bad compression, bad camshaft sensor, bad crank shaft sensor..


its a whole lot of things that can be wrong

[Ted]

If I had a bad crankshaft or camshaft sensor or something of the sort wouldn't I have a dtc code other then Engine Misfire though? The only codes I have on my car are P0300 Engine Misfire Detected, i think P1870 Transmission Component Slipping, and P1652 Fan #2 Relay.

[ October 11, 2003: Message edited by: Ted ]</p>

[jamie]

probably a wire. if they get close to the heat, they'll miss.

[BillyCobin]

fuel pump, fuel pressure regulator, fuel injectors

The wires could easilly be burnt in under 10k miles, even if they look good. Are they resting on anything?

[Ted]

I guess i'll look into removing all of them and inspecting them later on. I know a few wrap around one of the valve covers. I really hope it's not nothing serious like fuel pump and all that crap or a valve sticking. That would be a nightmare. I guess it couldn't hurt to use some fuel injector cleaner in the tank.

[ October 11, 2003: Message edited by: Ted ]</p>

[awesomeame]

a buddy of mine had this happen this past week. he got the car back on the road yesturday tho. he replaced the plugs, wires, checked the coils & they were all good. it turned out to be the ignition module. i'd start there first.

--matt

[Ted]

I'm going to do a plug and wire change this weekend, as well as test the ICM if it doesn't look good. I'm going to pick up some injector cleaner tonight, but off hand what are the symptoms besides a misfire with a bad fuel pump or injectors? Again, the problem only happens a over 2300-2500rpms, while under load. The car is fine if I rev it in neutral and as long as I keep it under those rpms. My friend says it doesn't sound like a plugs/wire issue because it would miss throughout the RPM range. I'll see how it goes though.

[Snuffalofogus]

ted im having the exact same prob, but my misfires kick in only above 3000rpms.

[Tyler]

i had a stuck valve..

seriously.. before you get into serious work with your car..

go out to your local Napa Autoparts store and get 2 cans of seafoam engine treatment.


Pour half, or a little less than half of one can into the oil. Then pour the rest into the brake booster line while the engine is on. Let it stall..then let it sit for about 5 min. it shoudl smoke like crazy.

then put the rest in through the gas tank.

i did this and my misfire was gone .. and hasnt come back

I changed plugs, wires, coil packs, ICM, injectors and was about to do fuel pump.

then i decided to seafoam it.. and 10 min later it ran perfect again.

[Snuffalofogus]

mine ended up being bad plugs, wires, coils AND! ICM.

i had the work done at the dealership so i took it in the butt on the price. The mechanic said that what was causeing the probs was there for some time! well, since i only bought the damn thing 5 months ago, and have put less than 4000 miles on it, that means that they sold me a *bad car*

i am therefore getting a discout on the work. 15%. its not much but im gonna try and get more outta them.