From Audi 100 to urS4 in a week

[hunker7]

I think the AAN is like ABY and has a section of metal vac line so there are 2 short bits of rubber line and 4 clips. If the rubber line is original it is usually leaking..

I am quite sure it's still all original

What I noticed with the "grey S4" ECU is, it takes longer to boost.

[newsh]

I think the AAN is like ABY and has a section of metal vac line so there are 2 short bits of rubber line and 4 clips. If the rubber line is original it is usually leaking..

[hunker7]

Worth swapping for the one from the other car and see if it makes any difference.
Also check the vac line to the FPR is good and solid and not leaking, if it leaks then it will run lean on boost.

I am sure I have the old one somewhere in my parts box Good point about the vac line don't think I've checked that. fingers crossed

[newsh]

Worth swapping for the one from the other car and see if it makes any difference.
Also check the vac line to the FPR is good and solid and not leaking, if it leaks then it will run lean on boost.

[hunker7]

If you are getting 18mpg with a heavy right foot, then your foot ain't heavy enough pal

Or I have one f0cking mint ride I will leave it in for now, and see what I average under normal driving.

[Error404]

If you are getting 18mpg with a heavy right foot, then your foot ain't heavy enough pal

[hunker7]

Here it says "May Fit" the AAN

http://www.ebay.co.uk/itm/Bosch-OEM-...item27e922e534

I have a donor car now I can play around with while it's not a runner

If i remember right, it looked different to one one AAN when I swapped it, but pressure was the same so I chucked it in.

[hunker7]

078133534A was superceded to 078133534C in 1998 but both were 4 Bar fuel pressure regulators so, in theory, that is not the issue (but I said *theory*)

I should have it somewhere, I will put it back in and see what it does, worth trying.

Gutted about the ECU though, not a cheap thing to buy. Is there any way of determining what's wrong with it?

[UrS4boy]

Here it says "May Fit" the AAN

Also says

Pressure: 4 bar / 58 psi

OE PART NUMBER:
078133534
078133534A
078133534C

So will fit.

[newsh]

Here it says "May Fit" the AAN

http://www.ebay.co.uk/itm/Bosch-OEM-...item27e922e534

[UrS4boy]

I just remembered, I fitted pressure regulator from my A100, part number is 078133534A, could that be the issue here?

078133534A was superceded to 078133534C in 1998 but both were 4 Bar fuel pressure regulators so, in theory, that is not the issue (but I said *theory*)

[hunker7]

I just remembered, I fitted pressure regulator from my A100, part number is 078133534A, could that be the issue here?

[UrS4boy]

Fuel Pressure Regulator Info

If that's okay, will get it to garage to check pressure in fuel rail (what it should be btw? 3bar? ) Could it be pressure regulator?

Your AAN has a 4 bar pressure regulator. This means that there needs to be 4Bar plus boost (or minus vacuum) in the fuel rail at all times. So less than 4 Bar at idle and 5 Bar when you have 1 Bar of boost (about 2.0 Bar absolute on the digital OE boost gauge).

Here is some reading for you:

Click on the fuel pressure regulator label (hyperlink) in this live version of my Engine Bay Device Map:

http://members.shaw.ca/speedtek/UrS%20Engine%20Bay%20Device%20Map.html

[hunker7]

Power problems might not be down to ECU, but fuel economy is, even driving it very very heavy footed( through rev range in 2nd/3rd) it didn't go below 17mpg, was up to 18.5mpg by the time I got ask home.

So things to check?
I will open the fuel tank, as I've been there many times, maybe some hose is squashed somewhere.

If that's okay, will get it to garage to check pressure in fuel rail (what it should be btw? 3bar? )

Could it be pressure regulator?

What else?

[hunker7]

It does not, half way through fitting new fuel lines, hopefully will be on Tuesday