P2187 plaguing me

Some background. So I bought myself an 06 gti United gray on December 31st. In true shady used dealer. Seems they had cleared the codes as the CEL lit up on the drive home. After reading the codes, I decided to fix it myself. Being my second car I wanted to try my hand at this. I've loved every minute of it. So it hard your typical lean and Underboost. Replaced the DV and PCV, spark plugs, did the oil , and 6mt fluid too. Cleared the codes. Lean returned. Air intake leak. Okay, K&N intake. CEL again, lean at idle. I work at a dealership, smoke the car. Leak from vacuum port, buy gasket kit, rebuild vacuum pump. CEL again. At this point I've gone in circle and at a bit of a loss. So, the pcv I had bought was off of Amazon, cost me about $25, so obviously this is a likely culprit, as I do have oil in the pcv hosing and I am burning oil. Just changed the oil again 2 days ago (about 3k miles since last one) and it was very dark. Black in fact. So, rambling done, in your experience. Should I replace the PCV for an OEM one as this code seems to usually be that component from what I've read. Or could it be worse. RMS? My belly pan always has moist/damp oil/dirt on it.

Thank you for bearing through my incoherence.

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I did not have the code you did, but it was a running lean code none-the-less. Check out my last post on this thread and check those parts I had to replace. Maybe yours is shot as well. Best thing I did was spend a few bucks at home depot and bought some propane to spray around the engine bay to help find the cracks in those hoses. Hope yours is as easy to resolve!!

So a new development. I was watching my STFT while parked. And nothing. It made no sense. So as I'm thinking I begin to tap my foot. I tap the brakes. Repeatedly. STFT shoots up. Audible revving as I continue to pump brakes. Bad brake booster? Perhaps torn diaphragm or crack in the housing?

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Check the hose that connects to the left side of the brake booster. Mine was hella split. Pretty sure the only reason my brakes were still holding was due to this diaphragm keeping the pressure despite the hose being ripped open.

easy87 said:

Check the hose that connects to the left side of the brake booster. Mine was hella split. Pretty sure the only reason my brakes were still holding was due to this diaphragm keeping the pressure despite the hose being ripped open.

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I considered lines for a while. Did as you reccomended and got a propane torch. Tried leaking it around. Did it while squeezing some lines. No luck. I did some research around. And found a video of someone with a crack in the back of the booster on the diaphragm side that was causing a lean condition. It kinda makes sense since when I come to a stop I throw it into neutral. So the computer reads this lean at idle. I ordered the parts from ECS. Genuine VW. Lucky the booster was on sale. Installing it next week once it comes in. Will let you know.

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TikTokOddity said:

I considered lines for a while. Did as you reccomended and got a propane torch. Tried leaking it around. Did it while squeezing some lines. No luck. I did some research around. And found a video of someone with a crack in the back of the booster on the diaphragm side that was causing a lean condition. It kinda makes sense since when I come to a stop I throw it into neutral. So the computer reads this lean at idle. I ordered the parts from ECS. Genuine VW. Lucky the booster was on sale. Installing it next week once it comes in. Will let you know.

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You could have tested your theory and just remove the hose at MC booster and plug the hoses and see if you still have the issue at idle.

Sounds good! Good luck!