Sorry guys kind of a newbie on these audi's. I have an 99.5 a4 1.8tqm. it is completly stock. I just installed a boost gauge and i seem to be peaking at about 5 psi and it levels out back to 4 psi. it spools right away but stops at 5 psi. Is that correct? If this is wrong, what should i do to check what is wrong?

 

Your wastegate line that gets reference boost is broken/disconnected. The car has a fail safe to default to 5 psi so if that line breaks, the car wont overboost, run lean, and empty the contents of your block on a road somewhere. I'd personally replace all vac lines (the stock stuff is crap) with 5/16 hose from your local auto parts store. I picked up 5 feet @ $1.50 a foot

 

I'm not sure what's wrong, I'm positive however, that this would fix it. Probably a little pricier than vacuum line for 1.50/ft
http://shop.achtuning.com/aprt310002...1audib5a4.aspx

 

^^ True, but I'm pretty sure that's whats wrong, cause when I got my boost gauge, I removed that front intake manifold hose cause I was impatient and stuck the gauge hose right in there and drove to hope depot for my T adapter on 5psi, 10 minutes in the parking lot and the drove home with 10, spiking 12.

 

i am having the same problem with mine right now...when i get the time sometime this week i will get the vac line from a parts store and do all new lines. thank you for helping out

 

Well i checked the vac line from the wastegate and it seem that its ok. im still changing the lines but when i started to take things apart i saw a fitting that was missing hoses. this fitting is attached to the intake hose. Can somebody tell me where they go. here is a pic. You can see the left hose is broken and the right one is not even there. help please

 

Ok i think i figured out where these lines go. i looked for a vacuum diagram, could only find a b6 1.8t. dont know if they are the same but that pic i posted is the n75 and i think one line goes to the wastegate and the other goes the the turbo. please let me know if this is correct. who ever had this car b4 really did a number on the vacuum lines.
when i took it apart the turbo line was going straight into the wastegate and that intake hose was the way you see it in the picture. .

after switching the lines i drove the car around....now im hitting 7 psi. Is stock 10 psi?

 

do to what these guys were talking about, I was wondering if a cheap guage is just as good just to test it.
http://www.summitracing.com/search/?...e&Ns=Price|Asc

easiest hook up?!

 

Might need to do a boost leak test. Ill find the vac diagrams, I saw them recently...

 

Here you go