AuZZZie

First off I realize diagnosing & troubleshooting over a forum isn't exactly easy or effective, but I'd like to be armed with as much information as possible before I take it in and there are some intelligent people on here.

I have a 2007 997.1TT that is throwing some codes.

Codes:
P2189 - System too lean at idle bank 2
P2187 - System too lean at idle bank 1
P0507 - Idle air control system rpm higher than expected.

Behavior:

I noticed a few months back that occasionally while coming to a set of lights, clutch in and the revs would rise 500rpm or so then gradually come down. Sometimes they would hang at 1200rpm is then come down after a few seconds.

No codes at this point.

Then I through the codes and while I'm seeing the same behavior, it has rev'd higher than it was previously. It also hangs and takes longer to let the revs come down. It also isn't idling too well. Idle will dip, it catches it and they return to normal. Rinse and repeat. There is a repeatable pattern to the idle seeking.

It is going in next week but I if anyone has some ideas for things I can check myself that would be great. Too me (and my amateur backyard knowledge) it feels like a vac or intake leak. The plumbing on this car is so difficult to access though I really can't find anything obvious from the little I've poked around.

Welcome any feedback.

Cheers

Petza914

The fact that it's happening on both banks is usually an indicator that it has to be something common to both, which is good as it likely eliminates one bad O2 sensor, one bad coil pack or plug, etc. You may very well be on the right track with a vacuum leak - if you open the engine lid, can you hear any whistling from anywhere? Are the intake pipes clamped on securely. The other thing it could be is a bad MAF - these fail more frequently on Turbo cars than on the NA ones. One test you can do would be to unplg the MAF and drive it. Does it drive worse, the same, or better. If it's the same or drives better, then you've likely pinpointed the issue. If it's worse, that's not much help as the MAF can still be partally working but still not working correctly.

Is the intake on the car stock or are you running an aftermarket intake with oiled filters, like K&N? This oil can coat the MAF wire and cause issues like this. If you have an aftermarket intake, go to the auto parts store and get a can of MAF specific cleaner - remove the MAF from the intake and spray the sensor wire liberally - do not touch it and do not wiipe it. Let it air dry and put it back in. If you've alredy logged codes, they likely will not go away unless cleared, but you may be able to tell if the car is running better even if the Visit Workshop light remains on.

Also, you may want to post in the 997 Turbo specific forum as those guys probably have more experience with the forced induction engines.