My friends 99 A4 has a loss of boost, can anyone help....

[elijahallen]

He just got it chipped by speed tuning. There was an obvious gain in power but he didn't have a boost gauge so it was hard to tell if it was at its potential. He just installed a gauge and we only saw 11psi max the first day and now its only boosting 7-8psi. I pressure tested from turbo down to TB with no leaks. I changed the N75 for one I had extra. I replaced the BPV for a know good one. We unplugged the MAF and there was no change in boost. I looked at it with Vag and everything seemed to be working right. We went through all the vaccume lines and they were all fine. The turbo spins free with no shaft play. I am stumped, can anyone shed some light for me on this. I thought it would be something simple and it might still be but I can't seem to find it. Speed tuning says it should be boosting around 16psi. Thanks for any help.

Elijah

[prey]

He just got it chipped by speed tuning. There was an obvious gain in power but he didn't have a boost gauge so it was hard to tell if it was at its potential. He just installed a gauge and we only saw 11psi max the first day and now its only boosting 7-8psi. I pressure tested from turbo down to TB with no leaks. I changed the N75 for one I had extra. I replaced the BPV for a know good one. We unplugged the MAF and there was no change in boost. I looked at it with Vag and everything seemed to be working right. We went through all the vaccume lines and they were all fine. The turbo spins free with no shaft play. I am stumped, can anyone shed some light for me on this. I thought it would be something simple and it might still be but I can't seem to find it. Speed tuning says it should be boosting around 16psi. Thanks for any help.

Elijah

Could be the coilpacks or spark plugs, have u checked The vacuum hoses near the brake booster. you are prolly loosing boost pressure there, check each and every hose again and bend and twist it.

[turboquattro068]

is it running fine, besides it not boosting higher?

[elijahallen]

is it running fine, besides it not boosting higher?

Yea, it runs just like stock but a little faster now. Today I found a vaccume leak at the grey/black vaccume valve by the airbox. Boost came back to 11psi max but still short of the 16-18psi that the SW is supposed to work at. I finally just decided to do it the easy way and put a MBC on it. It worked great, I set it at spike to 17psi and the car runs pefect now. I'm lost now, seems like the N75 should be to blame but Vag shows both of the ones we tested to be fine. Anyone?? Thanks,

Elijah