Boost stops at 1.4bar - N75?

[hunker7]

If this happened after changing or working on the cams then as Paul mentioned check the mechanical timing.
Hope you get sorted soon.

On last couple of pages you can see what was wrong

http://www.s2forum.com/forum/showthread.php?t=70571&page=30

[mastermind]

If this happened after changing or working on the cams then as Paul mentioned check the mechanical timing.
Hope you get sorted soon.

[S2central.net]

They do - just checked with by best girl 'KATE' lol

[hunker7]

According to your above quote fuel pumps are the same.How did you come to that conclusion?It's of interest to me as i have AAH and ACK fuel pumps and could use as a spare for my AAN. Cheers.

http://www.vagcat.com/epc/

Says AAN, ABC and AAH runs the same pump.

[S2central.net]

I was talking to myself lol. Will look it up tomorrow unless someone beats me to it.

[Vorsprung durch Technik]

and i can do that at the click of a finger.........not, and don't know where to look.

[S2central.net]

A quick check on the parts system will confirm.

[Vorsprung durch Technik]

AAH,AAN,ABC run the same fuel pump, so that can't be the problem.

According to your above quote fuel pumps are the same.How did you come to that conclusion?It's of interest to me as i have AAH and ACK fuel pumps and could use as a spare for my AAN. Cheers.

[S2central.net]

If you have G40 at the cam sprocket then it doesn't need to be separately aligned... G4 is indeed the crank ref sensor - the G40 & G4 pulses should arrive at the same time every other crank rotation... if they are far out of whack you don't even get an engine start so you should be fine although there is great confidence in actually seeing it.

My gut feel is an air leak on this one - you need the bungs and a methodical approach to check everything.

Have you checked for a torn WG diaphragm ?

Might there by a hole in the intercooler that has been overlooked ?

Check you have good solid 5V at the throttle pot and the altitude sensor as well - should be a red wire from memory on each of those when key is ON.

[hunker7]

Thanks for the suggestions S2 central.

AAH,AAN,ABC run the same fuel pump, so that can't be the problem.
Timing is now good, but I will take it all apart on Sunday and do it up from ground up.

I don't understand what you mean by G40 and G4. G40 is behind cam sprocket, and G4 is by the gearbox?

[S2central.net]

I've not read all this thread, but I suggest all the fundamentals are checked - along the lines of -

- Mechanical timing... double check the timing marks and be certain the sprockets aren't skewed off (damaged keys)
- Does this AAN engine have the G40 camshaft sensor in the dissy housing - if so check it is aligned too
- Check that G4 and G40 signals are aligned properly (needs oscilloscope) - G4 must appear in middle of the G40 window
- Don't mess around with F96
- Get a proper boost leak test
- Use only known good fuel pump - must be 3B/AAN/ABY/ADU spec pump as a minimum - not any old Audi 100 pump
- Check you are getting full throttle when you mash the loud pedal - measure/check volts at the throttle pot
- Are you clearing fault codes to ensure the ECU isn't holding a fault which disables active boost control (N75 disabled) ?

Also - if you are using the UrS4 boost gauge as your reference point then keep quoting its results on the same ABSOLUTE scale or we will go a bit bonkers.

[Vorsprung durch Technik]

Easier to just tell us what the digital gauge is reading.

And that was my post a couple days ago but the suggestion just vaporized into thin air Why not use "absolute" pressure of the cars digital gauge instead? Would make life easier for lesser mortals and no more confusion.

Janis, changing the fuel pump to the 2.6 pump has surely got to be a negative?

[hunker7]

What i do find weird is that fuel pump will run occasionally when car isn't running, as in getting the pressure up in the system.

I tried starting the car today, it sort of starts but wasnt picking up the revs.

I did swap fuel pump from my A100 into an S4..could they be different?

[newsh]

I know but then all the S2 boys with Vacuum-0-Boost type gauges start saying things like.. "1.8bar is too much, you should only be getting 1.3!"

[UrS4boy]

One final suggestion before I fly over to Blighty to scope out Art Deco buildings in London, etc.

From jretal on my home forum:

"he check to see if the cats were clogged? when in doubt and nothing else is found to be wrong, loosen the flange before the cats and remove the donuts and see if you have boost again. "

Good luck. I trust it will all be sorted when I get back.