Boost leak help! B6 A4 1.8t

[JAYB1RD]

First, the engine mods: GIAC Stg 1, test pipe (stock cat back), silicone TIP, APR R1, MBC, and CX Racing FMIC. If I remember right I've added some preload to the waste gate and it should not run any lower than ~10psi. The K03 has been rebuilt before and there's minimal oil residue in the stock turbo hoses so I feel like it's just fine.

I've been having boost leak issues with my car since last fall. Before the snow fell I found a torn hose between the turbo and crossover pipe. So I rigged up a cheap/quick fix with a piece of exhaust pipe and extra hose clamps because I didn't really have a good place to work on the car. It went from 0psi max to 5psi max! I was finally able to keep up with traffic again...barely LOL

Now I have a garage to work in again and have spent the last few nights under the car. I've installed the FMIC and did a bunch of boost leak testing which did show me a couple leaks. One big leak at the banjo fitting on the compressor housing and a tiny little leak near the TB. Zero leaks from the new FMIC plumbing! I also put 20psi of shop air to the waste gate and it seems to be in good working order as well. So I fixed the leaks, tested to verify, and drove the car down to the gas station. It hit 18-19psi for the first time in a LONG time! Felt great, until I put my foot back down a second time and it slowly built up to 5psi again like usual. I'm still having the same problem, this is getting to be very frustrating.

I'm out of ideas now. The whole reason I got the FMIC was to eliminate the leaks! Anyone have some advice? Could it be an intake or exhaust manifold leak once the car is up to temp? I've had each of them off before without replacing the gaskets. I feel like I'm running out of summer weather to enjoy my car with!

[JAYB1RD]

Well, I ended up pulling every line that holds boost (DV lines, MBC lines, and boost gauge line too) and replaced with new stuff from my local parts store. Only cost me like $10 and an hour or less of my time so I figured why not. Re-tested with 20psi and didn't hear any leaks. Once around the block though and it still wouldn't hold any more than 5psi. So I gave up, cried like a girl, kicked the tires, had a beer, and went to bed.

The next morning on my way to work it was peaking over 20psi and holding 10-12psi! My boost gauge needle was very jumpy/shaky on the way up too, but held steady once over 15-ish. After a day or two of that it has now returned to completely normal and is now smoothly boosting to 17-18psi every time. So I'm not sure what the problem was, but it's fixed now and has been for maybe 2 tanks of gas. Just wanted to post my result in case someone's searching and looking for answers.

Stupid cars...LOL

[stolnheartdealr]

What methods are you using to test for leaks? I hook up my compressor to the TIP with a homemade fitting and dial in 5 psi to start. I too have been testing leaks for a LONNNNG time and I'm finally down to a handful. My oil cap, my oil dipstick and the PCV tube on the top of the oil filter housing are the only leaks I have left. Not exactly intake though, should I be finding ways to seal these up better?

[JAYB1RD]

Well, after a couple more times of driving the car and losing boost I've concluded that my car is going into limp mode. I always assumed the check engine light would flash when in limp mode but apparently not. There are no boost leaks and my waste gate works as it should. I'm getting codes pointing to a bad thermostat though and when I reset the codes I get full boost again. So, fingers crossed, a new thermostat should fix my issue.

I use a similar boost leak test method, I made an adapter to swap out the MAF then I unplug my crankcase breather and MBC hoses. I've also got an adapter for the plumbing just after the turbo. I start out at ~10psi to make sure there at no huge leaks and then I go up to 20.

Sounds like your leaks are normal crankcase/blowby leaks. I wouldn't worry about them. Unless the one by your oil filter is causing a mess or leak of course. I bought an aluminum adapter (from 034 I think) to put a hose on mine. I will be getting a catch can at some point for it as well.