Boost problem?

**mistert396** · 07-07-2008 12:17 PM

I started noticing that when Im hitting boost my car seems like its kind of surging and struggling to get there. Then today on my way back to the house I was looking at it a little more and it would hit boost spool to 17 psi and then it would shut off to 5 psi. Is this limp mode? If so what could be causing this? Im currently searching for boost leaks and wanted to see what you guys think. Thanks in advance.

**2k1audiS4** · 07-07-2008 12:46 PM

TBB....I had the same problem. When I got to 12 PSI I would hear a rush of air and I would loose power. I found 4 tears in my TBB. Samco TBB and problem solved for me.

**RolledMySTi** · 07-07-2008 01:12 PM

5psi is definitely limp mode. I would pressure test first. TBB is a good place to check.

**mistert396** · 07-07-2008 01:17 PM

Thanks for the reply's. If it is the TBB would you recommend replacing it with Samco? I've heard that using the APR Bi Pipe gets rid of this problem as well. Also is it something that needs to be fixed ASAP or would it be alright to wait a week or so?

**mholme** · 07-07-2008 01:46 PM

Originally Posted by mistert396

Thanks for the reply's. If it is the TBB would you recommend replacing it with Samco? I've heard that using the APR Bi Pipe gets rid of this problem as well. Also is it something that needs to be fixed ASAP or would it be alright to wait a week or so?

If it is your tbb, I would get it fixed ASAP. The bipipe will fix torn tbb problems, it's also about 5 times the cost of a silicon tbb.

**mistert396** · 07-07-2008 01:57 PM

Alright, after doing another test drive with it, its acting differently now. The boost is coming on strong to 15 psi but then it seems to be in an in-between mode. It is surging like full boost and then none. It does this repeatedly while holding down the gas pedal. Is this typical of the TBB or possibly the diverter valves. I know those will soon need to be replaced as well.

**mholme** · 07-07-2008 02:03 PM

Originally Posted by mistert396

Alright, after doing another test drive with it, its acting differently now. The boost is coming on strong to 15 psi but then it seems to be in an in-between mode. It is surging like full boost and then none. It does this repeatedly while holding down the gas pedal. Is this typical of the TBB or possibly the diverter valves. I know those will soon need to be replaced as well.

You should pressure test/VAG the car. If you still have stock diverters, then yes, they should be replaced as well.

**2k1audiS4** · 07-07-2008 02:03 PM

I would be willing to bet money you need a new TBB. I bet I can even tell you where its torn. Its torn along the clamp that holds it to the throtle body. Check it.

**mistert396** · 07-07-2008 02:08 PM

Haha right on the money. Good call man. I will get it fixed as soon as my Samco shows up. Thanks.

**mholme** · 07-07-2008 02:11 PM

Originally Posted by 2k1audiS4

I would be willing to bet money you need a new TBB. I bet I can even tell you where its torn. Its torn along the clamp that holds it to the throtle body. Check it.

That's a bold statement..I'd take some of that action if I hadn't sworn off gambling

But yeah, they do commonly rip there. Here's what mine looked like.

**2k1audiS4** · 07-07-2008 02:35 PM

^^^^Same place mine ripped except about 4 more places around that edge. I think Audi should do a re-call on all TBB's and give everyone samco boots. I know it would never happen but just wishfull thinking i guess.