13g boosting problems

[willthiswork]

I've got a 93 TSi AWD auto, and I seem to be getting boost surge of sorts.

Everything runs fine until I hit 8-9psi (which is the limit for this crap 13g turbo, I know) and then if feels like the wastegate is flapping or popping, because the boost will start surging all the way to 14-15psi.

Obviously it doesn't run/accelerate properly when it's doing this..
Only modifications that it has are a K&N airfilter and a MBC (which is dialed down all the way)
Anyone know what the symptoms sound like?

 

[greysave]

Does the boost spike or does it maintain this high level of boost? Check the vacum hose on your wastegate to make sure everything is connected. I had the same problem in a turbo msp, and found out that the wastegate was disconnected. The only difference between your problem and the one I was having is that the car was pulling alot harder at the higher boost.

 

[willthiswork]

Does the boost spike or does it maintain this high level of boost? Check the vacum hose on your wastegate to make sure everything is connected. I had the same problem in a turbo msp, and found out that the wastegate was disconnected. The only difference between your problem and the one I was having is that the car was pulling alot harder at the higher boost.

It does spike.. it will fluxuate 3-4 psi and the you can certainly feel it in the car.
To my belief, the 13g's wastegate is only set to hold up to 9psi of boost.
I figured because of this I wouldn't get any more, thats why I'm wondering what else is going on.


The kid that I traded the car from had NO idea what he was doing with DSM's and the MBC wasn't set up properly. I re-hosed everything using the profec B manual that I had from my previous car, so it should be correct now.

Could it be that the wastegate itself is broken?

 

[kenamond]

Do you mean creeping instead of surging?

If the wastegate was opening prematurely, wouldn't this limit your boost rather than cause it to creep?

Could the wastegate be sticking closed or be damaged or the MBC be shot?

 

[willthiswork]

Do you mean creeping instead of surging?

Could the wastegate be sticking closed or be damaged or the MBC be shot?

Yes?

I don't know what the exact problem is, but i've had 2 seperate MBC's on the car, with similar results.

So I guess that means my wastegate is probably toast?

 

[kenamond]

I'd do a search on diagnosing wastegate actuator problems. I've read that you can test the wastegate with a compressor or bike pump to make sure it opens the wastegate flapper as expected, but a search would get you more details.

You can also check for creep by disconnecting the wastegate actuator arm from the turbine housing. While the actuator arm is off, see if you can open the wastegate by turning the flapper arm on the turbine housing manually. Leave it disconnected and do a test run watching the boost gauge. It shouldn't go over a few psi if you have proper flow out of the wastegate (the wastegate door is free to open). If it does boost much higher than that, you may have a creep problem.

 

[twack]

i have this same problem on my 13g. thought it was a bad uage until i looked into the issue a little further. but i guess its creep cause my mbc isnt installed. the 3 inch exhaust without cat eally made it go funny