8L S3 Overboost

[S3quatt]

Overboost issues

Hi all
I recently swapped out my MAF to try to cure my lumpy idle problem. I'm not sure if this is the cause of the following problems or not, but after that the pressure started surging & ended up in limp-home mode.

The boost pressure before the swap was maxing about 23psi. After it sits around 25 & over (off the scale) then goes into limp-home with a max of 5psi.
I've checked the DV & it's ok, & it sounds ok IE. No leaks.

Now the car was supposedly mapped by Star Performance, but going by the MAF readings both old & new on Vag-Com i'm guessing it's standard. Max reading 183gs.

I've also put the old MAF back in & the car's still the same, still overboosting.

I've called Jim at Star & found him very unhelpful, basically telling me what i already knew.

Going from what I've read on this & other forums, I'm thinkin the N75.

To add to this, I've just hed the n75 off & checked the hoses. I found the one going to the wastgate actuator blowing right through.
I'm sure this should have a sealed diaphram the same as the DV. Is this correct? If so, i guess i've found the prob...

Does anyone have any other ideas?

Thanks in advance.

 

[S3quatt]

For anyone interested...

I found the fault.
It turned out the car is fitted with a Forge wastegate actuator & the diaphram was burst.

A quick call to forge & they had a replacement sent up the next day free of charge!!!

Top marks to Forge Motorsport!

 

[HTC]

Good good. I'm in the same boat as you. I'm thinking for some reason my wastegate isn't opening. Hopefully it's just an actuator problem for me too.

Cheers for the info.

 

[bham a3]

Hi I had a similar problem with my Audi A3 1.9 TDI 105 BHP to find it was very slugish, I found that one of the pipes was split. which has now been replaced. Is there any other signs that it could be wastegate actuator? How do you know weather the diaphram has blown? doesnt the actuator plug onto the side of the wastegate? Does the standard A3's use a Forge wastegate? If so can you send me the number please.

 

[S3quatt]

The standard wastegate has a sealed actuator from what i can make out.

The Forge one is an aftermarket part http://www.forgemotorsport.co.uk/content.asp?inc=product&cat=010201&product=FMACVAG01

To check if the diaphram's gone, disconnect the pipe going from the n75 to the actuator & try to suck it or put on a vacum. if you can draw air then its burst.

Hope this helps