It Begins: The S3 1.8T into my '85 Mk2 GTI

[GOLFBALLS]

Ok thanks guys, its all excellent help!!

I will stick on another n75 off grants or gareths motor (hehe). Qpeng guys reckon there isn't much a manual boost contol can do that the n75 doesnt already do??

And yea, the timing is ok as it would be running bad all the time if it was out (the VVT is only a functional system for valve overlap during cold starting). I havent actually really noticed a misfire at all but it could still be there.

I will check the voltage to the fuel pump just to be safe also.

Also in addition to the wide band tester reading lean: it will read lean also because the oxygen hasn't burnt?? I'll press that matter with the tuner again.

[Volksee77]

Do you want to just buy my new haltech off me and be done with it????? Sitting in the box still and unused. Going to be that way for at least 6 months mate if you want to consider it?

[tommymac]

Yer un burnt oxygen causes uber lean reading. I think the 75 Valve sends odd readings I don't really know but I pissed mine off

[Dscott]

yep N75 for sure. My bets

[gareth_oau]

I replaced my n75 valve last month.

car was running perfectly, except absolutely nil turbo performance.

If you need to trial it Wade, gimme a yell

[gareth_oau]

hey Wade, some S3 bits for sale here, not sure if anything there interests you:

Lots of standard s3 parts - Audi-Sport.net Classifieds

[Dscott]

N75J is on ebay...

WGFV, N75 Valve, J Version Genuine VW Audi Part - eBay, Volkswagen, Car Parts, Vehicle Parts Accessories. (end time 31-Oct-10 22:16:37 AEDST)

on more thing, "what is this part"

"A small electro magnetically operated vacuum 'solenoid' that is controlled by the cars ECU to control turbo boost pressure under load."

You're having boost pressure issues under load true?

[GOLFBALLS]

Cool thanks guys.
I'm not actually having any boost problems at all. I am having problems with fuel supply while under boost pressure at full load.
There doesnt seem to be any misfire that i can hear...

I'm going to step back from the issue for a week or two, get some other little things taken care of, and come back to it after i've done some more thorough homework on turbo mapping and fuel supply etc.

There are a few things I'm considering:
-intake air speed too slow under load causing fuel dropout in the manifold
-a misfire (that i cant hear)
-injector timing out of phase at high revs
- voltage to fuel pump
-mapping software is too slow correcting between throttle position to MAP pressure defaults
-????there's nothing wrong at all and the tuner's testing equipment is crap????

[tommymac]

cannot be fuel surely, I have a standard lift pump and and 040 with a custom surge tank. But even if you upgrade to a mk3 tank and run a 040 inline it will be fine (baffle in mk3 tank to prevent leaninging out on corners with low fuel levels). hell even a 040 inline with a mk2 set up will work for testing and if that doesnt flow enough well then something is really wrong somewhere.

[MattyT]

Updates????