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

[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????

[Golf Loon]

Ok, I run the 20VT Engine on the scirocco on the QPEng system and I had untold problems with running rich till I set it up.

I have played these games before and so when I sent off the loom etc to qpeng I also got Ben to buy me the sensors and pump that he knows work well with the system.

The fuel pump he supplied is a standard GTI pump from a KJET MK1 GTI!!!!!!!!
This has massively higher pressure than a digi or VR6 pump and is moving a much larger quantity of fuel.

I agree with Gavin that the pump flow not the pressure is the problem. Your pump flows enough to cope with not boosted driving, but when the turbo demands more fuel, it cant deliver. I just have a lifter pump in the tank, standard and same as your Mk2 pump, then the main kjet pump and a 3 bar vw FPR. By slowly increasing the revs you are making the miss and leanness less obvious.

Try the N75 valve as it is easy to fit and test, but I reckon your main pump is not up to the job.

Also would be good to get someone else to chack the timing. Fresh pair of eyes

[Golf Loon]

The more I think about it, the more I think it is fuel delivery.

I have a few brand new kjet pumps here. Hit me up if you cant get one closer.

[GOLFBALLS]

Hmmm. Thanks for that Loonster.

Problem is the old mk2 tank is long gone as i've put in the mk3 tank for the vr pump!
I've also deleted the accumulator/reservoir.

So why would the qpeng guys say that the VR6 pump would be fine when I told them???

[GOLFBALLS]

Hang on, if I just leave the VR6 pump there as a lift pump, and add the k-jet pump to where the accumulator used to be it should work ok yes?

Is that k-jet pump a stand alone unit that i can just add in to the supply line?

Cheers,
wade

[Jarred]

if they reckon the VR pump is fine, would a swirl pot help for when it hits' boost?

[GOLFBALLS]

if they reckon the VR pump is fine, would a swirl pot help for when it hits' boost?

Swirl pot? Sorry, I dunno what ya mean...

[MattyT]

Surge tank is perhaps what he means??

I assumed that you were running a full S3 fuelling setup. Ie, S3 fuel pump, pressure reg, lines, etc etc. But if you're not then what loon said stands to reason, I guess (not being a mechanic I honestly dont know).

[Volksee77]

man just spend the $200 and get a bosch 044 motorsport pump, that should give you all the fuel you need

[GOLFBALLS]

I am going down the mega fuel pump route yes. I didn't put the whole S3 fuel setup in because according to my research all accounts claimed the VR6 pump and standard mk2 lines are totally adequate for the job.

I'm going to test out the k-jet pump from Grant and see what happens and take it from there.

Cheers

[GOLFBALLS]

In the meantime, I did a few little jobs the other week. The front steel heater pipe was leaking water where it goes to the block on the front.
Check the old o-ring!!!


Then I took out the rad and mounted up a fan while i was at it.




I also put it up on sarah's grandads hoist and put some new Lemfoerder top mounts in to stop the rattle.
The old mounts were pretty shot and the bearings had totally collapsed!
It stopped the rattle for about a day but its back now There may be a washer missing... I took some pics on my phone but they look crap.