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Rough Idle Multiple Codes

L

low budget

Passed Driver's Ed
It all started a few weeks ago, out of the blue the RPMs would surge to 1500 or 2K at idle, and it was throwing a P2187. So I changed the PCV diaphragm and fuel filter. PCV checked out ok, when I drained the old filter it had some crud in it. Still getting same problem, but now getting codes for miss fire on multiple cylinders. Rough idle, runs fine at 1200+ RPM while driving.

Car is tuned, not sure what stage. Aftermarket intake and intercooler. R8 coils. Car has 119K, new to me at 99K.

Any ideas? I can't seem to find a boost leak anywhere either.
 
M

Mk6 Steve

Ready to race!
Check the spark plugs. They may need to be changed and/or regapped.

Derp! I was busy at work when I replied to this....Check all connections to the pcv. If everything is connected properly then its possible you need to do a carbon cleaning at that mileage. Also, what kind of crud did you find in the oil filter??
 
Last edited:
L

low budget

Passed Driver's Ed
Mk6 Steve said:
Check the spark plugs. They may need to be changed and/or regapped.

Derp! I was busy at work when I replied to this....Check all connections to the pcv. If everything is connected properly then its possible you need to do a carbon cleaning at that mileage. Also, what kind of crud did you find in the oil filter??
Click to expand...

It was the old fuel filter. And when I drained the fuel out it was cloudy, nothing sold or chunky, just murky fuel.
 
M

Mimog3

Passed Driver's Ed
I'm going through the same thing right now. I have the p2187 system too lean at idle and p2279 intake air system leak. I too replaced the pcv diaphragm and it removed other codes I had such as the p2015 on the latest revision intake manifold.

I'm going to replace my rear main seal because I've read that a blown pcv can blow out the weak rear main seal. You will know your rear main seal is blown when you see oil and the point where the engine block and transmission meet. If you see oil there then you've found your problem.
 
Boscogn

Boscogn

Go Kart Champion
This sounds like carbon clean would fix. System too lean code is talking about not enough fuel likely from dirty fuel injectors. Misfires might be dirty plugs but not system lean faults I would think. I'd go ahead and replace these anyways if they haven't been serviced recently. If u do end up carbon cleaning snag the revised intake manifold while you're at it. You won't need to buy a new gasket for carbon clean as new intake comes with one. They should be able to put it in without extra labor as they'd have to pull the intake manifold anyways for carbon clean. New manifold is ~$150. Carbon cleaning is usually around $600 shop around. My quote out the door for carbon clean and intake was $750.

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L

low budget

Passed Driver's Ed
Changed the PCV last night. No longer getting intake air leak codes. But getting a misfire on all 4 cylinders. Slight stumble at idle, but runs fine above 1,000 RPM.
 
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