I have had this problem for awhile. I have an early 99 A4 1.8tq. I have an APR chip, and it has always worked great. However, over the years I believe I have developed an illusive boost leak. The car is still better than stock, but has noticeable turbo lag. Here is what is going on. In first gear with the K03, it is a little slow to spool, but will boost fairly strong for mostly stock car (not quite as punchy as it should be though). Second is fairly strong as well. It is at this point you can faintly hear a slight whistle. Go into third and floor it, and you can feel the boost come one with a nice whistle very audible as boost increases. As the whistle gets louder, the power tappers off. Same goes for fourth and fifth. In fifth on the highway, if you step on it to pass (even in forth or third on city streets) the car will go, but without any authority and accompanied with a nice whistle.

I have worked on VW's and Audi's for years. I have owned more than one VAG 1.8t vehicle. I cannot find the freaking boost leak on this car! I have checked IC piping. I have replaced a few suspect vac. lines. Swapped DV's. Checked clamps and replaced a few. But, its still there!!!

Now, I would be checking all avenues of the intake track on my bentley CD manual, but I CANNOT USE IT because i have vista!!!!! So I thought someone here might shed some light on my problem. I thought maybe one of the check valves could be allowing boost into the crankcase, but is seems unlikely. Maybe the injector O rings need replaced??? I have noticed a few places that look like they have accumulated blow by on some vac. lines, as well as around the injectors. If anyone has gone through this problem in the past, your help would be appreciated. I know the B6 has a typical boost leak vac. hose problem that was common on the early models, so I thought maybe my car has a similar problem and fix. I want to be able to fully enjoy my car again.

Thanks in advance.

 

are not really conclusive. Be sure to buy one that has vacuum as well.

--dillon

 

i had a huge boost leak in one of the breather hoses under the intake manifold. if you install your boost gauge and find you have under 2 psi of boost check your wastegate. its pretty rare but mine just took a ****.

 

Yeah, I have a leak. Don't need a boost gauge to tell me that. I do however have a boost gauge. I am going to try and get it in on the weekend. I just don't have a pod for it. I was hoping to get a vent pod, but I haven't found one that doesn't come without the gauge.

When you lost about 2 psi, which it honestly feels like I have lost (after all these years of working on and owning VW's and Audi's). Did you experience a high pitched whistle under heavy load (ex: WOT)? If I am a little light on gas trying to avoid the whistle, the boost is more responsive. If you push it though, it dogs a bit. Also did you experience noticable lag in normal driving?

Thanks for the help. I checked the waste gate vac. line earlier today, but it seemed to be fine and properly sealed. Might have to look into the WG diaphragm too.

 

Get a gauge, quit asking questions till then.