stange problem

[white95tsi]

Just recently my stock turbo blew, I replaced it with a FP Big28 with a walbro 190lbh fuel pump. Everything was great for a few weeks. One day after work I noticed that my boost guage was dropping off shorly after hitting the max boost of 14psi. I checked for boost leaks and found the lower intercooler pipe coming off from the turbo was loose. I tightened it up and it was fine for a while. Now I have the same problem again and I cant find any boost leaks.

When the turbo hasn't spooled for a while, and I step on it, it will spool to 14psi, hold it for a second or two, and then drop down to 11psi, when I shift into the next gear it will only hold 11psi. It sounds like a boost leak but if it is I don't know where its coming from. All my intercooler piping is tight, and my 1G bov was bought brand new in may. I'm almost thinking that the turbo may be faulty because its very similar to what my old one did before it blew. I took off the intake pipe and checked for shaft play and found none. The turbo only has about 1000 miles on it.

I'm just lost now and can't figure out what it could be. I'm hoping its a boost leak, but my boost leak tester itself leaks and sometimes is hard to hear other boost leaks. I can't imagine it would be the turbo, because everything was installed properly and its brand new. If youve had a similar problem let me know.

 

[white95tsi]

Another thing I noticed is that it holds boost fine for the first 10 mins or so of driving, and only drops off after the car is at full temperature. I went to the local shop and the guy there told me that it could be a vacuum leak, so I bought new lines and I'm going to replace them as soon as my car cools down. Does a vacuum leak sound like a possible cause for this?

 

[flinguist]

You might have a boost leak. Check the couplings on your I/C piping. Here's a vfaq on how to make and use a leak tester. http://www.vfaq.com/mods/ICtester.html