I"m really starting to get fed up with my car.Im only getting 4-5 psi of boost.Sometimes ill get the full 8-9 but then it will taper off...I replaced my DV vavle,replaced the n75 with a mbc, checked for codes and checked for vacum/boost leaks. When all said and done i still cant find whats causing the problem.My turbo has 60K on it,do you think its time for a new one?I really need to figure out whats wrong,i have my GIAC chip and the mail and its no good to me if my car cant hold boost. I've used the search button tonss of times and the only other thing i can come up with is that my wastegate is sticking..


Thanks

 

Sounds like you are in limp mode. Get your ecu scanned and let us know what codes are stored.

 

I brought it to an APR dealer right near my house,they scanned my car for free and the only code they got was for the knock sensor...?

 

well a bad knock sensor might put you in limp mode.
here is something i found that sort of explains what could be happening:

" a missing knock sensor signal (bad sensor, bad connection, etc) that is causing the ECU to say, "Okay, I don't have a signal that I would normally use to control timing and prevent pinging, so the only thing I can do is just limit boost to that provided by the Waste Gate Spring, 6 psi. I will do that by commanding the Waste gate frequency valve to dump any boost over 6 psi until my owner goes out and buys and installs a replacement knock sensor"

From audiworld.

 

The guy at APR said that it wasnt related to my problem,i started gettng the knock sensor code when my ECM went and my car was on 3 cyl. The car started bucking crazily and Im pretty sure thats why im getting that code. I was having the problem before the ECM went and before I got that knock sensor code,but when the problem first started the boost was on and off,now its always off.I guess im going to try another boost leak test on it...im not sure what else to do.Like I said before the only other thing me or the guy at APR could think of is a sticking wastegate..

 

so I found a link that showed how to do a good boost leak test,so i got the parts and did it...there are NO leaks anywhere in the rubber lines..but i can hear a loud gurgling noise inside my engine,i cant pin point where its coming from...or what it could be

 

post up that link you used to make the boost leak tester!

 

http://forums.audiworld.com/a4/msgs/1659806.phtml

Thats the same basic setup I used. I but a cap into the intake right after the MAF,and another on the tube leading into the intake mani. Then i pluged the PCV opening on the intake and hooked up a compreser to the plug on the intake cap. When i got to about 12 psi i could just hear the pressure leaking into the engine.........I remember someone having the same problem in a thread on audiworld.Im triyn to find it right now,but from plain commen sense this doesnt seem good...


I also rescanned my car tonight and the only fault code i got was,knock sensor circuit low.So i cleared the code and went for a ride..same problem..

 

Just a Q what does a knock sensor cost, and does it need to be bought from the stealer? Would it be worth the $$ to replace it and see if it solves the problem?

Oh thnx for the boost leak post. I have been hearing an air leak when in boost and that helps ssssooooo much!

 

Not a problem, I actaully didnt use the sizes they say to use, I just used two 2" plugs and a cork for the PCV opening.But im not sure abou the knock sensor,after i cleared the codes and drove it,I scanned again and the code didnt come back..