Today i was driving going around 40mph in 5th gear speeding up and i was around 10 psi and my boost completely dropped to 0 and the car jerked forward then the boost jumped back to normal. Also during that drive my car wouldn't spike to 20 psi again and would actually only spike to about 12-13 and taper off to 10. Completely baffled as to what it could be. After shutting the car off for an hour it went back to driving normal (spiking to 20 psi/ holding at 15), completely baffled as to what it could be. I put in a 710n DV (it was good when tested), new maf and a bunch of other things. I also noticed some oil residue back behind the engine where the PCV valve is, not sure if i have a leak or what it really is, i visually inspected all the hoses and couldn't find anything obvious. Completely stuck at this point, scanned my car with vcds and i had no codes pop up. Thanks for your help in advance.

 

i wouldnt worry about it unless it happens again. i once had my car, when it was stock, completely stall in a parking lot. wouldnt move and sputtered under throttle. it was terrible. shut if off, turned it back on, and ran fine since, about 20k miles.my point being, **** happens and sometimes theres no describing what made it happen. but if i had to guess, id say maybe something with the n75 considering it controls boost.

 

Thats what i was thinking the n75, i just don't want to blindly spend $100+ on something and that not be the issue. The first time anything like this occurred was about a month ago when the car wouldn't go past 15 psi, it went away, and it re-appeared about 2 weeks again, and then it happened again. So clearly the problem is progressing.

 

well keep in mind, the n75 may just be the part that is materializing the problem. could be something with the tuning as well. id try a used n75 off a parted out vehicle for cheapness. if that doesnt work, you know you got bigger issue and it only cost whatever you spent on the used n75

 

Before you go buying a new or used N75, you can do some tests to check its functionality.

Disconnect the electrical connection and the car should not boost more than 5-7psi. The car will be relying on the internal waste gate spring only.

If you disconnect the vacuum line going to the waste gate and leave everything else connected, the waste gate will be kept closed and you should boost higher. Be careful doing this, do not go WOT, and do it in 3rd or 4th gear. Make sure you do not over boost, be careful.

Here is a good read: N75 wastegate actuator valve explained/symptoms. - AudiWorld Forums