Limp mode?

[s4mark]

Hi again
Just got back from running a mate to Gatwick and the S3 seems to have developed a niggle.
Boosts fine up to about 4000-4500rpm but then seems to hold back and struggle after that. Seems like its straining to pull past 60mph in third and I'm thinking that cant be right.
I have heard that it could be a faulty N75 valve.
Do you think its worth replacing that straight away or do you think I need it checking on Vag Com first. Dont really want to get stung by the stealers for a diagnostic but don't know anyone with Vag Com.
Any help or advice appreciated

Cheers

 

[jojo]

Doesn't sound like limp mode, as limp mode literally reduces the cars power output by quite a lot, like the turbo has been switched off, and it resets itself when you switch the ignition off and back on.

I would personally try disconnecting your MAF sensor first to eliminate it and see if it still splutters after 4k revs, the car will be running less power, but it should rev cleanly through the rev range.

 

[s4mark]

Thanks for your advice. I will have a go at running it without the maf connected and see what happens
i know my old s4 had a faulty egr valve which was causing it similar problems, Didn't even realise until doug at mrc replaced it and when i drove home it was like a totally different car

failing that may try and find someone with vag com local to me