2007 997S System too lean at idle bank 1&2

[copterjon]

About a week ago I got a CEL along with a bit of rough running. Also on occasion a bit of stumble on acceleration. I used my Schwaben scan tool to troubleshoot. I have two codes.
P2188 System too lean at idle bank 1
P2190 System too lean at idle bank 2
Anyone here have any experience with this situation? A generic search on the web lists a plethora of things that could be a cause. I'm hesitant to start shotgun replacing parts.
Oh, there is also a bit of oil smell in the engine bay. not like oil on hot pipes but rather like if the oil cap was left off. More of an internal hot oil smell.

[JFP in PA]

You are going to need that shotgun: You have a vacuum leak, which could be anywhere in the intake system.

[copterjon]

Originally Posted by JFP in PA

You are going to need that shotgun: You have a vacuum leak, which could be anywhere in the intake system.

Thanks! I'm gonna smoke it tomorrow and look at the intake system. Hopefully I don't have to pump too many rounds into it LOL!

[yelcab1]

Smoke it. This is one of the harder one to troubleshoot. You have a small vacuum leak and it is probably an old cracked hose.

[copterjon]

Ok, got around to smoking it yesterday and no leaks. I did notice that there was considerable oil in my plenum so broke it further down to change the AOS. I'm on parts hold as a few of the lines were quite brittle and broke on disassembly. Still have to clean the MAF and see what happens after she's all back together.

[copterjon]

Just a quick update on this ordeal. After smoking it and checking short term and long term fuel trims and a few other things it turned out to be a bad MAF combined with the failing AOS. I replaced both of these items as well as a fresh round of spark plugs and all is good. Car runs great again. One of the symptoms on top of the codes was it started shifting really bad (Tiptronic). It was also hesitant on acceleration. Never gave me any specific MAF codes just the lean at idle. Oh well! Job done.