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03-13-2012
A bad ICM CAN screw up one cylinder!
here is an idea grab the socket and ratchet to pull the 3 coils off in the oreillys parking lot unplug the icm walk inside and have it tested for free and go from there.............
I know they test them and I just called them to double check and make sure I wasnt loosing my mind either!
oh bring some money too if it is an ICM they are like 120 bucks IIRC.
03-13-2012
yeah its 125 at my work (advance)...and rico...you said random :P
03-13-2012
Yea, but I was trying to be a jerk. There is no such code.Originally Posted by 99pgpgt
I hope it is an easy fix. Without the tools sometimes it's so hard to diagnose these.
03-13-2012
it was a random misfire but now number 3 misfire will advance do it or autozone bc we dont have a oreillys
03-13-2012
ok they will test it at autozone i have tools. how do they test it
03-13-2012
I took the ICM off and between the bottom and the metal plate its pretty corroid i dont know if that matters or not but im going down to autozone tomarrow and get it tested let ya guys know how i make out Thanks for all your help so far
03-13-2012
Ok i took the ICM down to autozone and they hooked it up to a machine and they said it was good, so im stuck in tha same spot i was now, i dont know what else it could be? has anyone ever used that machine befor bc i asked the guy if i could go over and watch and he said no didnt seem like he hooked it up right is there another way to test?
03-13-2012
You said "theres spark coming from the coil both sides." If so, then your problem at cyl #3 isn't spark. Next thing you wanna do is see if the injector is getting pulse. If you're getting pulse and spark, then you most likely have a compression-ish issue or the injector is flaking out.
So lets make sure that you have spark and pulse.
03-13-2012
Follow this guys lead. He knows what he's talking about.
The injector signal can be tested with a DVM set on "Duty Cycle". This is an easy way to measure pulse width. Take note of the stability of the signal. Get a reading from one of the other known good injectors and compare it to the reading from #3.
If the injector signal is good then the PCM is probably good. Move on to a compression test. If the compression test is good then I would probably replace the ICM or install it on one or your freind's cars and see if their car produces the P0303.
Last edited by Rico; 03-14-2012 at 01:38 AM.
03-13-2012
A friend of mine has a 99 regal with the 3800 and he had the same problem, tried switching the injectors, had the ICM tested and replaced all plugs and wires, he ended up having to purchase a new computer for his car. As far as i know he hasnt had any other problems since, could be an option.
03-13-2012
hmmm icm can b checked by advance auto. just go by with ur icm and they can test it. its under the coils. take coils off and unplug the harness going to it. should come off . sorry i meant duralast wires but ur prolly right bluegtp. had to re route the wires when tune up. but upon bringing wires back to autozone, they replaced it 100% and it still hesitiated. so i went with denso brand and not a problem. so... i donno to each is own.
03-13-2012
Two and a half hours earlier...
Reading > YouOk i took the ICM down to autozone and they hooked it up to a machine and they said it was good, so im stuck in tha same spot i was now, i dont know what else it could be? has anyone ever used that machine befor bc i asked the guy if i could go over and watch and he said no didnt seem like he hooked it up right is there another way to test?
03-13-2012
its impossible to hook the icm up wrong...there is only one plug on the machines we use. you press start and tap the icm with a metal piece to simulate driving conditions. i always run the test 3 times to make sure. if it fails even one time i suggest replacing it
03-14-2012
well i switched plugs and wires swtched 3 and 5 had it scanned and it didnt change from cylinder 3 so i put a bottle of injector cleaner in it and a cup of mystery oil and cleared light. the light hasnt come back on yet! but the exhaust has a pretty big leak right after cat so maybe the leak is causeing a little ruff idle.
03-14-2012
plus im gonna do compression test on it tomarrow what should the compression be?
03-14-2012
In my experience compression tests don't tell you the whole story. Heck, most of the time they are done wrong and they tell a bad story about something that is fine. If you smell gas in the oil, do a compression test. If you smell gas in the exhaust, check injectors.
03-16-2012
I had a mechanic do compression Test and he said #3 cylinder had 60 PSI and the other ones had 170 so he told me i would have to take the head off and have it looked at. the car runs fine driving and it went almost 20 miles and the check engine light didnt flash or come on, then idling it came on, anyone else have a idea for me or am i screwed thanks
03-16-2012
You may have ball-peened a seat. Do you have the ability to remove the head yourself? It's easy, especially with our remedial valve train. Just make sure all parts go back on in the same place. If it is the head I would just go and get one from a yard. They're dirt cheap. The other option would be to have a machine shop do the work for you. That's if it's salvagable.
03-16-2012
If you say it runs fine driving and then idles like crap I have no idea how it could have a compression problem. If your still getting misfire codes I still think its ignition problem.
03-16-2012
So what you guys think would it cause a misfire code with a bad valve it runs great besides idle so would this do this with a bad valve
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