Alright so I drive an '01 1.8t and I just recently installed a boost gauge. I installed the gauge to try and troubleshoot because my car has had an odd issue that feels like a miss but may be air issues also. It's a real weird feeling lurch and I can't figure it out. From my understanding based on what I've read the stock boost for '01+ is supposed to be 11psi. When I first took the car for a drive with the gauge it was consistently boosting at the 11psi mark. Then next time I drove it and consistently after that it was stopping at 7psi. Now this morning when I drove it it was spiking to 11psi but dropped back down to 7psi immediately after. I can't figure this out. The only thing I can think of is maybe my understanding of the stock boost is off or the waste gate is sticking and not opening properly. If you have any ideas please let me know I'm at a total loss.

 

i think you're leaking. the spiking to 11 and holding 7 is normal but you should be holding 11. do you have a cel?

 

Nope everything is completely stock aside from the gauge. A leak wouldn't be fun I hope that's not the problem. They aren't easy to find from my knowledge.

I have noticed times when the turbo is boosting normally but it doesn't feel like the engine is getting it cuz I'm accelerating real slow and feeling no boost. I don't know if that could help point to a solution or not..

 

Sorry I didn't answer the question there. No there's no CEL just low wiper fluid haha

 

Best way to check for boost leak IMHO is the tennis ball method. Can be found on AudiDIY.com i think.

It requires a tennis ball, sharp object to poke holes in tennis ball, screwdriver, and air supply with sufficient flow and pressure reglator set to about 15 psi.

Its actaully quite simple and effective.

 

I'll have to give that a shot. Thanks

 

coming from another 01 driver, i dont think you have much of a problem. mine is a manual and in first it peaks at somewhere around 9.5-10.5 psi at about 3100rpm if floored and drops off to about 7psi before gear change. if you are going about 50mph and floor it in fifth (manual transmission), the boost should somewhat slowly creep to 11psi, hold for a while, and drop slowly. sometimes, my car while have a little bit erratic boost like peaking at 7psi and hold there all the way, but it doesnt really mean you have a leak. it just means the computer isnt controlling the n75 efficiently.
forgot to mention, the amount of boost delivered by the ecu, as i have found, varies on your driving. if you just give it to her all the way boost will be greater than if you decide to floor it half way through a gear. again, i can only speak for a manual transmission. i have only driven an automatic once, about two years ago.

 

^redline - I had an automatic and now have a manual and have noticed different boost curves as well, I plan to do some data logging and leak checking to get to the bottom of it

 

best way to check for a leak without even having to do anything is look at your boost gauge. you should be at -20 to -23 at idle and almost near -30 while coasting in gear. if you are closer to 0 then you have a leak after the TB.

 

Unfortunately the boost gauge I have stops at 0. Just sits on a pin at 0 when it's not boosting. I do drive manual (automatic what?) but this thing is unpredictable. Today it's been getting to right around 7 again and then holds there. I'm getting nowhere near the 11 psi I'm supposed to hit. Whether I'm punching it off the line or from mid-gear it's not getting where it needs to be. Sharp peaks or slow creeping it doesn't matter its not getting up there.. Still at a loss here