running rough!!

[Rootie524]

ok so i have a cammed 3100. got it dyno tuned. just not too long ago it would be running great then all of a sudden it would start running really rough and it sounds like a WRX STi. And by that i mean it sounds like this: http://www.youtube.com/watch?v=JNKFc...eature=related

last time i checked i have a malibu and not an STi so idk whats up. no it doesnt sound that cool its just something to compare it to.

i thought it had moments of misfiring due to bad plugs..i replaced all the spark plugs..and it just happened to me today on my way home. the plug wires are new. so now im thinking maybe a fuel problem?

it so hard to explain this accurately. it happens completely by random and goes away randomly too. i dont do anything different it just comes and goes. and sometimes it only happens at low rpms then if i rev it goes away past like 3-4k then comes back when its under that. i really have no idea. it's kinda pissing me off cuz it may sound like a STi but when it does this is certainly doesnt perform like one.

any help would be great. ill carry around a video camera with me so i can try and catch it on video so its easier. everything else seems to be in working order. and it started happened like 1-1.5 months after the whole cam thing. would too much ignition timing cause this?

[mickaz]

you will not receive any help from anyone until you post a video of the car running/idling. because what you just said is SO vague...

[Rootie524]

well after thinking about it for awhile i think its my crankshaft. something to do with that. that's my new hypothesis anyway..ill try to get a video up sometime.

[bszopi]

Your hypothesis is extremely fouled... Nothing to do with the crankshaft would cause random occurences of an issue.

[Rootie524]

then what else could it possibly be. i know if it were the crank shaft it would be all the time. but it happens randomly..shakes the whole engine/car, goes away sometimes when engine spins really fast, i just assumed it had something to do with the crank or the rods because of that and it seems to be internal. either its damaged, or completely unbalanced. because when i had to take the harmonic balancer off it was a bitch getting back on so i used a block of wood and a hammer to tap it back on enough that i could bolt it down the rest of the way. and i know your not really supposed to do that so im wondering if that fucking something up.

[86FieroSEv6]

Sounds more like you're dropping a coil to me. The question will be coil or ICM? I've "hammered" plenty of balancers on without incident, as long as you don't slam the shit out of it and only use enough force to move the damper till the bolt can grab it you'll be okay. If you're going to do it on a regular basis, an installer is a must, you can even make your own.

[Rootie524]

I hope that's all it is. because bszopi has a point, it would make no sense for it to be the crank i was just talking out loud because it just seemed like it could have been one of the problems. but it doesnt happen all the time so it wouldnt make complete sense.

but since the plugs were changed and the wires are good just keep going back and u get to the coil..so its possible. i hope its just a coil and not the ICM. i thought for a second it might be a plugged fuel filter but then it would probably just take a shit on me all together. is there anyway to check each individual coil for fault? the MIL only gives me random cylinder misfire sometimes it doesnt specify which ones.

[86FieroSEv6]

A scanner with misfire monitor hooked up in movie mode while the problem is happening would be nice.





That's right, I dream occasionally.

[Rootie524]

haha lovely. if only.

well it's cheap enough ill just replace the whole pack and see what happens. maybe they were on their last leg and all this ignition timing sent them over the edge. i dont know..we'll see. haha

[Rootie524]

well... i replaced the whole coil pack today because my car was running as if one of the coils was bad. so that went on..started it up..all went well. i cleared the MIL for random cylinder misfire and drove around. it still had a moment of misfiring like the rapid babababababa on steady acceleration. but i figured that may be because of the new spark plugs im using. i know these engines are pretty picky on the spark plugs they get. so im just like..no big deal. the MIL didnt come back on. then i go get gas. i started it up. the MIL pops on. fuck. but it seemed to be running fine. i drive around all seems fine..occasionally it'd do the bababab thing but nothing like what it was before. on my way home for about 40 seconds it did the crap that led me to replaced the coil pack in the first place. it is like an extreme cylinder misfire. it's ridiculous. did it, then went away. and when its doing it the MIL blinks on and off.

So I have no idea wtf the deal is but it's pissing me off. Things i can tell you are it was tuned and has quite a bit of ignition timing. it's tuned for 93 octane and lately ive been going to wawa which only has 92 octane..i dont believe that is the issue though or else it's be more constant. i just recently replaced the plugs with autolite app606's, the plug wires are bosch, and i just replaced the coil pack with one from a junk yard. I dont know much about the ICM or where its at but i aways thought it was the rectangle thing that the coils plug into but im sure im wrong.

so any help would be great. i dont think its all the ignition timing i have because i got it tuned awhie ago and it only started taking a shit on my a few weeks ago and its progressively gotten worse and is off and on so it shouldnt be mechanical. i had a scare awhile ago where i thought i bent valves by hitting pistons but if i had bent valves it'd be misfiring all the time i would imagine. but idk. help! thanks!

[robertisaar]

tap on your MAF at idle with the back end of a screwdriver, see if that causes something like it.

[Azrael]

You're thinking is right. The ICM is the tray all the coils plug into.

[Rootie524]

ill tap on the MAF tomorrow. i cleaned it not too long ago and when i plug my computer into the OBD2 and scan the sensors it gives a reading so it should be working. but ill check to be sure.

and yeah..then i replaced the coil pack with ICM..So it's not spark plugs (unless it's possible the gap is off..i got the ones it said to get for my car so im assuming the gap is fine..plus i was having the same issue with the old plugs and they were in since i got it..so i think its safe to say its not the plugs), its not the Coil or ICM.

It might be the ignition wires. they are bosch..and people say bosch spark plugs are shit in the 3x00s..so maybe the wires are too. i changed the wires at around the same time i did my cam shaft and they were used. so i can try that next. It could be (but i dont believe so) something fuel related..but that will all be checked last. I just really think its an ignition problem. And i keep going back to the fact that i have ignition timing advance. is that causing this trouble?

[bszopi]

What is the code that is triggering the MIL? That may help in narrowing down the problem.

[Rootie524]

it's very vague. just a simple P0300 Random, Multiple Cylinder Misfire