Ok, so i bought a 2001 Audi tt 225 about two months ago. Only upgrades so far are a MBC, boost gauge and a K&N intake. The car hasen't ran properly since i've owned it. The guy that had it before me must have taken the turbo off at some point because three days after i bought it, it had an exhaust leak. I original thought it was a crack in my manifold but when i got back there i found out that 2 of the 3 bolts holding the turbo on where missing. The taped in threads on the turbo had backed them selves out and wouldn't go back in so i purchased a new k04-022 turbo and put it all back together. One problem down and more to come. Now i have a leaky secondary pump and plan on drilling out the rivets and replacing them with better hardware.

My current problem is that when shifting through the gears the car wont hold boost. If i press the gas pedal down half way in 1st through 4th i will produce about 5-10psi and then it drops to zero and wont hold. Its only if i floor it that i can reach my max boost (20psi) and then it drops to about 10psi. My turbo seems to be pretty loud and when my boost drops it makes a SSSHHH sound, almost like my DV is opening prematurely, though i can still hear my turbo spool. Could this be a bad DV? In 5th and 6th gear my turbo is slower to spool but i can only reach about 10-15psi and when i step off the gas i can hear my turbo surge. This has me stumped. Could it be i need to adjust my wastegate? I was throwing up a code for my MAF so i am going to take it out and clean it. Could a dirty MAF cause this to happen?

I have checked all my hoses countless times and haven't found any leaks. I am planning on doing a leak test but just haven't had the time with work and everything. Not even positive if these are symptoms of a boost leak.

I'm pretty new to turbocharged cars but have been in the forums learning as much as i can. If anyone has any suggestions they would be appreciated.

 

if im reading this correctly then:
1. tht ssshhh sound ur hearing is the DV relieving excess boost whn ur throttle body slams shut whn u shift, u hear it now because of the intake, although if ur still on the stock DV n running 20lbs of boost, the diaphragm may be opening prematurely because it cant handle the boost, hence it drops off, the only time it should make a ssshhhh sound is whn u let off to shift.
2 u wont reach peak boost cruising around town, there isnt enough air flow over the turbo to spool it to full boost, and it reaches higher boost in 5th n 6th because the engine has to work harder to get the car moving so u hve to press the gas down more, meaning more air over the turbo, meaning more boost, and ur DV may not be opening quick enough making ur turbo surge and make a fluttering sound.
hope this helps, i had to read ur post a few times so i may hve missed something

 

Thanks for the comment. I agree with you 100%. I think the problem im having is a bad DV. I know i wont hit full boost driving around town, i know my post was kinda confuseing. What i meant was as i was building boost it was sounding like the DV was opening before it was supposed to. I am buying a Forge splitter this weekend so hopefully that will solve my problem. I also think my MBC might have something to do with it too. It was on the car when i bought it and it looks like a cheapo ebay controller. Gunna swap it with a hallman RX this weekend also. Again thanks for the post.

 

anytime , i hve a splitter on mine n it works great, easy to adjust too. and as far as the boost controller, buying a quality one will help greatly.

 

Well i got the splitter in first and test drove it, deffinitley an improvement. My boost was alot more consistant but still wasen't where i wanted it to be so i hooked up my Hallman Evolution RX kit and holly S#!T! Now thats how a TT should run. I set the boost to 21 PSI and sure enough hit 21 and held at about 19 through 6 runs. Thanks for the advice Cobra.

 

glad to hear its runnin better but at 21psi jst be careful ur pretty much at the limits of the stock internals, cause if u blow a rod its a costly repair, maybe turn it down to 19ish around town. but glad i could help

 

Yeah i hear ya. I definitley have no interest in throwing a rod or sending a piston through the top of my engine. I keep it set at 21psi but i usually dont hit that when im just driving around town, that is until a Nissan 350z rolls up. I dont know what happens, somehow the pedal is on the floor and im pulling full boost...Weird?

 

strange, tht seems to happen sometimes to me haha

 

Unless something is severely wrong with your motor, bending/breaking a rod is HIGHLY unlikely

 

Ok, so lets say I went ahead and bought an uprated FPR, how much boost would you say my engine could handle before im looking at causing damage to my engine? How much on the stock fuel system?