coppercivic

yeah stock injectors

coppercivic

is there any way to fix this? like bleeding off a bit of boost that the FMU sees, making it leaner?

WhiteTeg24

Well, with stock injectors, you shouldn't have to bleed off pressure to the FMU. If you know someone that has another set of stocks, I would try that. That's kind of cooky.

Rolla1990

It'd be nice if you could dyno your car, and use a wideband o2 sensor to see how it's running....

tranceminister

Yeah, it would be nice if you could tune it on a dino and see whats up with the motor, but I think Rolla's right. It's your FMU. The transition into boost with an FMU sucks. Correct me if I'm wrong but the fmu runs off boost pressure right? That means that your turbo has to start spooling before the fmu raises the fuel pressure. once the fmu kicks in thats the stumble your feeling.

leed

Try installing a bleed valve on the FMU vacuum/signal line.
Something that you could get from a Homebase type store. A small brass one maybe.
I never had this problem when I was using an adjustable tising rate.
I did notice if I had the rate of rise set to high, it would end up raising fuel pressure just before the boost threshold. It didnt stumble on my A6, but I backed it off a little just the same.

HTH

NINJA del Sol

How long has it been stumbling when you boost? If it has been doing the whole time you have had your setup, then you FMU is hooked to the wrong end. I had the same problem with my setup and I had the FMU linked into the fuel return banjo union. If this happens to be the problem, then go to the vortechsuperchargers.com and look at the tech section.

coppercivic

The FMU was hooked up right, i think i fixed the problem, i had my timing retarded 2 degrees and now i changed it back to stock and it works alot better, more power and no stumbling or alot less.

88crxSi

even though, the AFC would give u more tuning.