FPR question

[A80Avant]

what happens if you have the 3.8bar fpr remapped car and then you use the 4bar fpr without doing anything to the remap?
Will it be able to work,or will the extra fuel make it go rich,thus needing a remap again?

thanks
vasilis

[EspenW]

Fuel pressure spec is between 3.8 and 4.0 bar on the ADU, so upping the pressure ever so slightly probably wont warrant a remap.
Why not get an adjustable FPR and wideband oxygen sensor, that way you can tune air-fuel ratio yourself, not having to fork out wads of cash to a tuner every time you do a change.

[A80Avant]

well i have been offered a 4bar fpr quite cheap that is why i was concidering this.Is it possible to fiddle around with the boost pressure while keeping an eye on the EGTs to make the adjustments? i cannot use a wideband now..

[EspenW]

I have no experience with measuring exhaust temp, so I can't answer that. However, like I said, running the 4bar for should cause no problems.
During closed loop the oxygen sensor feedback will make it run at stoich, and you will run slightly richer at WOT.

[A80Avant]

ok then! i can give it a try then!
thanks for the info!!

[S2central.net]

This will be fine... well within adaptation limits on the fuelling for part-load cruise... Running on 4bar will give some extra richness at WOT if car is setup for 3.8bar. Very small difference.

[GT500]

When my fpr had decided to up the pressure to 4 bar (should have been 3.8) I had the 561 fault code, mixture addaption limit exceeded.
Your remap will be set up for 3.8, more fuel won't help.
Ever tried pulling the choke out on something old when its hot?= less power.

[A80Avant]

i see you point.
what will happen if i stiffen the wastegate screw for more boost as well then?
will that make a difference on wot?

[alg]

When my fpr had decided to up the pressure to 4 bar (should have been 3.8) I had the 561 fault code, mixture addaption limit exceeded.
Your remap will be set up for 3.8, more fuel won't help.
Ever tried pulling the choke out on something old when its hot?= less power.

Any chance someone had fitted an ABY one by error ?

[A80Avant]

i know this is not the proper way to get any more power,but since i have a modifing wastegate spring,i can get more boost and monitor the EGTs for WOT and keep them cool...Getting it more rich is not an option.So maybe if there is a bit of more boost there it can use the extra fuel....in theory...(i hope no tuner is reading this....hehe)

[GT500]

Any chance someone had fitted an ABY one by error ?

Nope, It had 3.8 bar on the side, bought the exact same from the Bosch part number stamped on the side. Old one 4 bar tick over new one 3.8.
Runs much better, no 561 anymore!!!!

[Jamo]

I remember chatting to slow2 who had rich running issue at 4 bar and dropping it to 3.8 bar made the world of difference.

Suppose it really does depend if the ECU can adapt to the difference in fuel pressure. If you have a wideband lambda it would be easy to see.

[A80Avant]

ok then i might keep it for future remap or something then and get the 3.8bar fpr for a replacement.

[EspenW]

Hmm, interesting. RS2 repair manual says pressure (when measured) should be anywhere from 3.8 to 4.0 bar. At part throttle, lambda feedback should keep AFR around 14.7 w/o problems, but it will run richer at WOT with higher fuel pressure. In theory, going from 3.8 to 4.0, it shouldn't be much, though
I'm running at 5.8bar at the moment (MTM used to run ADU injectors at up to 7bar). A/F stays right around 14.7 (flucuates, as it should between 14.5 and 14.9) at part throttle and dumps to the target area of 12.0-12.6 at WOT and with boost.

[alg]

Nope, It had 3.8 bar on the side, bought the exact same from the Bosch part number stamped on the side. Old one 4 bar tick over new one 3.8.
Runs much better, no 561 anymore!!!!

doing mine, code has gone with new MAF to TURBO samco tho