Boosting problem and its not the TBB.. Any ideas?

[doublebogey2]

Been extremely busy with work and havent had time for my car. I didnt drive it actually took the bus. Anyways last night I got time i ordered a samco tbb and went to install it last night. Mine was perfectly fine. Really stumped. I have no idea where to look next. The car is definitely not boosting as much as it did say 3 weeks ago and it happened all of a sudden. It was boosting to 18-19 now its just reaching 15. I also noticed a new problem last night. For some reason in first gear its not registering any boost sometimes and other times it boosts to about 8. Anyone have any ideas. Could it possibly be a boost gague problem. Im thinking its not because it is still registering. Anyone with any ideas id love to hear them. Thx.

[Turbo Nerd]

What year b5 do you have because you might have a flux capacitor problem.

[VR4-S4]

Have you done a boost leak test?

[doublebogey2]

Yes. Nothing. Even tried using water with soap. No bubbles or anything. Any ideas?

[IamEzraM]

Scan for codes, it could be EGT's

[noxplode]

x2. if you have access to a smoke machine thats the most fool proof way as well.

[bigern45]

quould be uno malo turbo..

[twinsnailsS4]

Sorry to dwell on the TBB, but did you check under the clamps for tears? Also, do you feel any stuttering or hear/feel misfires (ignoring what the boost gauge says for the moment on boost)? If you don't have a VAG, find someone to scan for you.

[doublebogey2]

I scanned it last night and there were no codes. I bought a new samco tbb put it on and its doing the same exact thing. As for a smoke machine I do not have access to one. anyone else have any ideas. i really appreciate everyone's imput so far. thanks

[Slow4]

Check the boost guage lines....you could just have a leak with that; possibly giving you bad boost readings.

[S4NIK8]

My 2000 is actually doing the same thing right now, no boost leaks and the vagcom says its asking for 18psi but only getting 14. I was thinking a bad N75 might do this?

[doublebogey2]

I will check the boost lines but I guess the only thing left to think of would be a bad boost gauge. That doesnt explain why im gettin 0 boost reading in first gear or sometimes it goes to 7 psi. Really stumped. I read another post where a guy thought that a temperate change might have something to do with it. Im not totally sold on that tho.

This might sound like a stupid comment. Where the hell is the N75??

[ski&drive]

I will check the boost lines but I guess the only thing left to think of would be a bad boost gauge. That doesnt explain why im gettin 0 boost reading in first gear or sometimes it goes to 7 psi. Really stumped. I read another post where a guy thought that a temperate change might have something to do with it. Im not totally sold on that tho.

This might sound like a stupid comment. Where the hell is the N75??

If your referring to me im pretty sure its not a ambient temp problem... however the n75 is on top rear of the passenger side of the engine under the engine cover. Symptom of a bad n75 are fluctuation in boost which sounds like could be your problem.

[RitchS4 914]

What dv's are you using ? If stock that might be your problem also.

[doublebogey2]

Im using apr dvs. is there any way to check the n75 to see if its bad. im not saying your wrong i am just wondering why its not showing up on a vag com.

[robbar25]

Having a similar problem, good luck.