Rough Idle and MIL

[sadj2885]

I've had a rough idle for a little while and today got a MIL with a few codes. I noticed a smell of coolant also and the serpentine belt started squealing a couple days ago, which could mean I have a leak somewhere, but the MIL codes don't seem to be related to that. Gas mileage has dropped significantly I think, as well, but that could be related to the cold weather the past few weeks. Any idea what I could be dealing with? I did put in an AFE filter a couple months ago, if that may have something to do with it.

P2187 - System Too Lean at Idle Bank 1
P0507 - Idle Air Control System RPM Higher Than Expected
P2279 - Intake Air System Leak

Thanks in advance.

[pierreb]

Check pcv, particularly the diaphragm.

[sadj2885]

Seems to be that, actually. I replaced the diaphragm last year with the repair kit from Advanced Auto. I guess it didn't last very long. Ill replace the entire valve this time as opposed to spending another $30 on the repair kit. thanks for the help, I would have never thought the diaphragm would go so soon.

[pierreb]

The amazon one I paid $17 for a year ago held up pretty well on my q5.

[eljefe1981]

I got the 2279 and the 2187 at separate times. Ordered coils and pcv. Will install one at a time to see which helps the rough idle.

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[eljefe1981]

Replaced both the coils and the PCV and it only helped a little. It is still shaking at idle.

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[pierreb]

Replaced both the coils and the PCV and it only helped a little. It is still shaking at idle.

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Still getting codes?

What happens to your idle if you disconnect the pcv hose from the IM?

[00SantorinS4]

How's your rear main seal look? Leaking any oil? It would be very obvious if it was.

[eljefe1981]

Unless I'm looking in the wrong spot I don't see oil coming from the rear main seal. After I changed the PCV I don't get codes but there's still some roughness in the idle.

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[ducati]

I thought if you changed the PCV yourself you had to bring the car to the dealer to get it reprogrammed.

[00SantorinS4]

Unless I'm looking in the wrong spot I don't see oil coming from the rear main seal. After I changed the PCV I don't get codes but there's still some roughness in the idle.

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If you only replaced coils and not the plugs (or if you know they haven't been replaced in a long while) I'd move to replace the plugs as well. They are cheap enough. It made a world of difference when I replaced my plugs and went with red top coils at the same time. Just shooting out ideas.

[eljefe1981]

The plugs were replaced about 2 months ago and it was really smooth idle. I was thinking of checking the plugs to see how they are.

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