I have a 2002 TT225 with an apr chip and turboback exhaust. When I am in stock mode the car runs perfectly fine and normal however when I am in the stage 1 high boost mode I have a problem.
The turbo spools up and boosts normally, but in 3rd and 4th gear at full throttle approaching 5000rpm the boost spike at almost 2o psi then hesitates suddenly and rather violently and all the way to redline. The boost then plummets all the way from 14psi to around 4-5psi. Previously the boost would never go below about 12psi. The car shows no fault codes and the CEL does not light up. Any thoughts before I start going broke down the wrong route. Because I don't want to just start throwing parts at it. Thanks in advance for any help.

 

Did you get a new TIP with the chip. I am not very experienced with all of this yet, but from everything ive read, that could be the cause. The tube will collapse around 5000-5500 rpm, causing boost to drop tremendously. Dont knock me if im wrong! just a thought

 

If it's fully collapsed though wouldn't the performance be affected while at stock boost as well. I am currently thinking that I may have either a bad coilpack or a bad n75 valve as I understand these parts to be more likely to fail under high boost situations.

 

typically the tip can withstand stock boost demands, but when you are running higher boost, as in your case with the apr chip, it can collapse.

 

If you had a bad coilpack the cel would flash with misfires. It is most likely a torn dv or collapsing tip like stated above. The 225 has a one peice hose that connects the maf to the turbo and it sometimes can collapse at higher rpms with higher boost levels. The reason for this is the higher boost + higher rpms require alot more air than one of them by itself and the tip will collapse like a straw. A good flowing intake can sometimes help prevent this from happening and a silicone tip will prevent it all together.

 

burner..i see youre from canton...i will be moving back to youngstown here in a few weeks...small world..

 

nice nice! i was wondering if anyone on here lived near me. it is a small world!

 

Thanks for the help guys. If I'm going to spend almost 200 bucks I want to buy the part most likely to cure the disease. Since I already have an upgraded dv it must be the tip.

 

What plugs do you have in it? My car was doing the same thing then I spent $9 and bought some BKR7E NGK's and now it is great.