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ROUGH IDLE when Warm STILL :(

W

wilk84

New member
Alright, so i posted about a rough idle awhile back and took a few suggestions but the issue is still there. Update: 1999 GT 3.8. Once driven to operating temps, once turned off and restarted shortly there after, it has a very rough idle. It didn't throw an engine light codes until about a week ago. Once I arrived at autozone to get the codes checked out, it went off. They went ahead and plugged it in, it was showing cylinder 2 misfire. In the last month I have replaced the plugs, wires, IAT sensor, cylinder 2 coil, fuel filter. Do you guys have any suggestions before I put a bullet through the gas tank? Thanks guys!
 


Sure did. I bought bosch at first but then took them back for iridium AC Delco's. It said misfire on cylinder 2
 
I wonder if when the ICM gets hot, its start to turn faulty and give you the misfires.

Got anyone you know that you can try and swap them for a bit to see if that might be the problem.
 


Hmmm, if you could point me in the right direction of doing that, I'm sure I could do it myself. If not, I will keep trying until i get it :)
 
They are kinda pricey, that kinda why I said to see if you got anyone you know with the same car and see if you could swap them real quick and see if the issue goes away.

I cant tell you for sure its the problem, so I dont want you to buy something you dont need.
 


I had the same issue with my 99 Grand Prix GT. Cylinder 5 was misfiring when the engine was warmed up and I ended up ordering a $76 ICM from Rock Auto and have not had an issue since. If only Cylinder 2 is misfiring, swap the coil from a working set of cylinders and see if the issue moves with the coil pack, if not; you are looking at a ICM. I also noticed when replacing my ICM the aluminum plate that it mounts too was a bit corroded from coolant. I wire brused the aluminum down so it made good contact with the ICM. Think of it like a cooling heat sink for the ICM.
 
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