Boost stops at 1.4bar - N75?

[UrS4boy]

J valve - works a treat on my aan
http://forums.audiworld.com/audi-ori.../#post18772235

But based on that article (which is also linked in my N75 info post), the stock 283H AAN WGFV should be better than the "J".

But whatever floats....

[geneandbolly]

J valve - works a treat on my aan

http://forums.audiworld.com/audi-ori.../#post18772235

[UrS4boy]

N75 WGFV info and review of N75 options

Pertinent N75 PN's are:

034 906 283 J = stock 3B (in 200 20v and S2)
034 906 283 H = stock AAN (UrS4 and UrS6)
034 906 283 K = S2 ABY and RS2 ADU

http://forums.quattroworld.com/s4s6/msgs/20987.phtml

[geneandbolly]

oh 2.1 2.2 you will never see..

i beg to differ, old chap . ..

[geneandbolly]

If you want our help, please be consistent with what you are reporting as "boost".

if you want to help us simpletons, then please give us the right information, you fanny!! (nb:"fanny" - a glaswegian term of mocking and endearment for someone who spectacularly makes an **** of themselves but you don't hold it against them)

[QUOTE=UrS4boy;802479]Good news/bad news:

Good news: The UrS6 moisture trap is located in the passenger cabin, by the ECU, not on the firewall. That means the hoses are not subject to heat shrinkage, etc. and tend to not come off the moisture trap.

i checked my s6 today and was puzzled for some time trying to find this mystical moisture trap . . this is what my car looks like . .



anyway, like i suspected, it's the n75 that was to blame. i replaced it with the J version (part no. 034906283 J - thanks spink!), fitted new clips etc and took the car for a blast tonight - it's like a new engine in there now!!!

the dud n75 valve:



the replacement J valve:






no spluttering/ hesitation at 4000rpm+ any longer - it pulls strong and right round the rev range without any trouble whatsover.

i love this old car annnnnd i can actually work on it without getting skint knuckles - what's not to like!!

[UrS4boy]

LHD and RHD UrS6 Moisture Trap Locations

i have an identical problem with my s6. ..., but will try that moisture trap first!

Good news/bad news:

Good news: The UrS6 moisture trap is located in the passenger cabin, by the ECU, not on the firewall. That means the hoses are not subject to heat shrinkage, etc. and tend to not come off the moisture trap.

Bad news: The hoses tend to not come off the moisture trap = you can't solve your problem with a 30p gear clamp or too.

LHD UrS6 moisture trap:



More moisture trap info: http://forums.quattroworld.com/s4s6/msgs/20401.phtml

RHD UrS6 moisture trap (unannotatd base photo courtesy of Popdemic):

[UrS4boy]

Oops. See below.

[hunker7]

i have an identical problem with my s6. first run with vag com showed up a fault with the n75 and the latest test didn't show up any fault! anyway, i got a new n75 which i'm hoping i'll get the chance to change today, but will try that moisture trap first!

thanks for the tip..

Let us know if new N75 fixes the problem

[geneandbolly]

i have an identical problem with my s6. first run with vag com showed up a fault with the n75 and the latest test didn't show up any fault! anyway, i got a new n75 which i'm hoping i'll get the chance to change today, but will try that moisture trap first!

thanks for the tip..

[UrS4boy]

Does the MTFS cut boost like it does on the ABY / ADU with the over temp alarm? If it does, then it's worth testing the MTFS by getting the car up to temp, disconnecting the plug and going for a very short run.

No. For the AAN, the MFTS only drives the coolant temp gauge, nothing to do with the ECU. The AAN ECU gets the coolant temp info from the G62 ECT sensor on the back of the head.

[hunker7]

Thanks for the suggestions guys, will try them all tomorrow, and see what happens.

[Monkeymagic]

Having been through this very recently if you have VCDS plug the 2x2 leads into the OBD1 ports. Select 01 Engine and then in the right hand set of boxes select 08 output tests scroll through the various valves ISV Evap Injectors and the last one is N75 when you click slect the N75 shoould audibally click away until you click end.
If that works then it would suggest the N75 is functioning and the ECU is sending the signal.

[Rusty]

Does the MTFS cut boost like it does on the ABY / ADU with the over temp alarm? If it does, then it's worth testing the MTFS by getting the car up to temp, disconnecting the plug and going for a very short run.

[UrS4boy]

N75 WGFV info and review of N75 options

I belive the N75 is the problem,try to disconect it,and on conection of n75 bring 12v.When u make positive conection on N75 he shud click.If dont click its not working

I think you will also need to supply a ground for the N75 for this test. Apply 12V power to the male pin on the N75 that is normally connected to the female pin on the red harness wire and ground the male pin that is normally connected to the female pin on the other wire (Yellow/red on an AAN). If you get a click from the N75, that would mean the N75 is probably okay. However, it wouldn't necessarily mean that the ECU is controlling it properly. This is where the other test, via the fault code testing connections will prove that the ECU is talking to the N75 and that the N75 is responding.

http://forums.quattroworld.com/s4s6/msgs/20987.phtml

[Majorcina]

I had this problem,same boost.
I belive the N75 is the problem,try to disconect it,and on conection of n75 bring 12v.When u make positive conection on N75 he shud click.If dont click its not working