RolledMySTi

After running fine last Tuesday my car decided the following day that it didn't want to make boost worth a damn. If I floor it my boost gauge jumps to 0 and then crawls up the the proper psi and I mean crawl. The car runs perfect except for not wanting to make boost. It also is louder and at all rpms and loads. Like there is a hole in the muffle or as I believe a wastegate stuck open. It also has a slight metallic buzz around 2-3k rpms.

I pressure tested it and everything was fine. It does it with my old N75 and a brand new one. I bypassed my N249 as well to no avail. I have vacuum tested my wastegate lines and they hold vacuum fine. I think I have a wastegate some how stuck open. Any other ideas? If it is a wastegate stuck open how do I fix it? Thanks in advance.

ChucktownS4

sounds like a plugged exhaust

RolledMySTi

I have APR downpipes. I was running it hard for 30-45 minutes the night before it died. Do you think I could have melted/messed up my cats?

RolledMySTi

Any other ideas?

ChucktownS4

thats what it sounds like, maybe you can put it on a lift and loosen the exhaust past the downpipes and feel the back pressure with your hand, you can try the muffler but its pretty far back, i had a old volvo turbo that did the same thing, after running the car hard pop the hood and look and see if the turbos are glowing bright red, my volvo did this.

otherwise its hard to tell, if you bypassed the n75 and waste gates it hard to tell, it should of boosted, maybe take the waste gate vac line loose also and carefully boost it around the block and see if it trys to peg the gauge,

otherwise make sure you are not in limp mode

ChucktownS4

yeah just re read the post, if it crawls to the desired boost you either have a plugged exhaust or intake, check your air filter also,

RolledMySTi

Well I have a stuck open passenger wastegate. Somehow where the wastegate attaches to the actuator rod came off and now the wastegate is jammed open. Any ideas as to how to fix it short of pulling the motor?

ChucktownS4

i cant believe one stuck waste gate would loose all that boost, but i guess its possible, anyways start with putting the car on a secure lift or jackstands, then yank the wheel off then inspect then axle off, take the spindle loose, until you can access the waste gate, maybe someone else will chime in, otherwise you can drop just the sub frame without yanking the motor, you need a top motor support bar to support the motor when you yank the subframe loose

macsnob

Any luck fixing your issue? Curious because I have the same symptoms... the car was running perfect with a fresh RS6/EPL setup . Requesting 23psi, spiking to ~26psi at 4000RPM and settling at 23 with no drop. Then, suddenly no spike, slow and low boost, barely reaching 19psi at around 5500RPM. Car feels laggy fast but nothing like the animal before.

So far, I've replaced the N75 (2x), APR R1's, torn f-hose and checked for boost leaks.

Any ideas? My wallet is scared.

justinholly

on my 200 s4 6 speed once i remove the DP'S and and heatshealds on can get to any part of the turbo so try that first..