shreader247

I no longer can hear my turbo blowoff, so I assume that it is no longer putting out any boost. Installing a gauge this weekend to find out for sure. Friend tells me that when it used to make some noise it sounded like a compressor surge, fans were spinning backwards maybe. I know very little about turbos, so any insight as to how to fix it or if I can would be awesome

shreader247

I also am unsure which line to run the tube to when i install the boost gauge. Everything i have seen says i need to attach it to one that will give me boost and vacuum, but I have no idea which it is on my 93 S4

UrS4boy

a) you should not be running a "blow-off" valve (BOV). You should be running a bypass valve (BPV). In addition to being ricey, BOVs result in temporarily running rich between shifts because metered air is lost from the system.

UrS4boy

b) you should "T" into the boost/vacuum line as it leaves the black moisture trap (looks like a black 35mm film can) under the fire wall connector rack cover (if your car still has one).

UrS4boy

c) you can get power for the boost gauge light from the UrS4 ashtray light.

ThetaTau87

Your car would be dog slow if it was making no boost. Have you noticed any other changes besides no longer hearing the BPV?

shreader247

okay cool, i need to find that spot to "T" into, i just need to find a T that is small enough or has a female connector on it because this tubing i got the the gauge is really small.

I have not noticed any other changes except for not being able to hear the turbo, so i am not sure if it is making any boost or it is just not building up.

shreader247

i finally got the gauge installed and it is registering around 10-15 psi in 2nd, same in 3rd. Havent gotten on a highway so i can see the what it runs in higher gears. but I am not registering any boost at all in 1st, is that normal?

UrS4boy

You should get 16 or so psi all the lower gears under wide open throttle (for a stock car). Me thinks you have a boost leak somewhere.

shreader247

wide open on the highway today i got 5 in first, around 10-12 in 2nd-4th, and i can get 16 psi in 5th. so it seems like 5th is the only gear that is getting the right boost.
what would you say is the easiest way to find a boost leak?