Sporadic idling / Rev hang... MAF Issue? "P2279 Intake Air System Leak"

I figured ill just make my own thread about this.

So on my way home i came to a light and i noticed my car is revving up to around 1200 rpm on its own, then back down to normal then up a little and back down.. ect. Then it would shutter for a brief moment then back to normal and hold fine. However as soon as id tap the gas again it would do it all over again with no particular rhythm to it. At full throttle the car runs fine. The issue is simply at idle or whenever off throttle. Any clue what this is about? See mods below. Intake has been on for 10K + miles, and i went stage 2 about 2 months ago.

I scanned the code with the Torque app as well as an OBDII diagnostics scanner, and they both read the same code. So I re tightened all the clamps on my intake after reading a few other threads about air intake leak issues, but its still idling the same. Then i removed the MAF to see how it would idle after that, and still no success. Same exact thing.

Idk what else to try. Do you think the issue would be before the turbo or after?

I would start by checking the all the connections and hoses post turbo. If that is not the issue i would suspect the PCV is sticking. Good luck

Im thinking your right about the pcv system. do you know exactly what it is in there that gets stuck? I've heard of this issue but im not really familiar with it. Is it related to the tune? Im getting all sorts of misfire codes on every cylinder, and finally the check engine light came on. And a new code saying too lean at idle, which i figured already as to why it always revs up and then back down.

I dont think its a leak in any of the pipes. I went through earlier re tightening everything, and the car runs fantastic still. All of its power is there (aside from a slipping clutch).

I put the car back into stock mode just now. I guess ill just take it to VW tomorrow after work. Hopefully they'll help.

Im not sure what gets stuck but the they only sell the entire unit so there's no point in trying to pinpoint. PVC systems have always been prone to failure in most cars i don't think it has anything to do with the tune but it might be grounds for a replacement under warranty. If you remove the dipstick while the cars idling do the symptoms go away?

ZLEB said:

Im not sure what gets stuck but the they only sell the entire unit so there's no point in trying to pinpoint. PVC systems have always been prone to failure in most cars i don't think it has anything to do with the tune but it might be grounds for a replacement under warranty. If you remove the dipstick while the cars idling do the symptoms go away?

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I see... well that's good to know. Haven't tried that yet. Ill test it out.

Im gonna try to take it to VW tomorrow.

Well nothing changes at all when i remove the dipstick.

Im about to to head to the dealership now. We'll see what they say.

Sounds like a vacuum leak

Bump, hi all!!!

Any updates on issue?

Thanks.

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Im guessing a vacuum leak. I actually just had this code along with the idle fluctuations. Ended up being rear main seal failure which was easily diagnose-able as oil was leaking between engine and trans. Also maybe PCV which usually goes hand in hand with a rear main seal so hopefully it hasn't failed yet.