ludelvr

so what r the causes of running lean once the engine hits boost? I mean, when I'm spooling and the turbostarts kicking in, it is reading rich on my autometer air/fuel gauge, but as soon as it hits peak boost (7psi) the air/fuel goes right to lean. Keep in mind that this is at full throttle. At part throttle, it stays on the rich side but once I hammer it, it goes to lean.

Aeka GSR

tell us your full setup

BoostinDC2

dont rely on the autometer a/f that thing is junk

Aeka GSR

i can vouch for this. Malice GSR fried his rings becaues of one.

ludelvr

well, as it stands, I'm running a bosch in-line fuel pump, a vortech 8:1 fmu, my stock injectors, which are about 330, and I'm using a ct-26 turbo regulated at 6.8 psi.

Aeka GSR

im going to have to say i dont trust that A/F gauge and you should go take it to a tune shop to figure out whats going on.

ludelvr

k, I'm concluding that it's my fmu that's causing me to run lean up top. I say this because when I hit boost, even at 1 psi, my fuel pressure gauge isn't moving. My a/f gauge stays in green at part throttle, but even when I slow push it to 3 or 4 psi, my fuel pressure gauge is still at around 37-40. Any one else have problems with their fmu or know how likely it is for these things to crap out?

dustin

Sounds like the FMU isn't working.

And in general, if your a/f gauge reads LEAN, then your running LEAN.

Factory o2 sensors are very good at detecting rich and lean conditions, they just cannot tell how far..

Dustin

ludelvr

it kinda makes sense, cuz when I try and punch it, it slowly goes to red and when it's in read and the boost starts to climb, the fuel pressure is still at around 40.
can I repair my fmu or do i need a whole new unit?

Tuan

I have the same problem!!! As soon as i go past 3-4 lbs it runs straight to lean...I have a Paxton FMU, i'm getting a Vortech one soon, to see if it fixes my problem.

ludelvr

yah, I think mine is faulty or something. It's a vortech too. Well, let me know how ur setup works out once u change the fmu. When will u be changing it anyway?

Xerxes

agreed! If your autometer gauge says you're LEAN or STOICH under boost, then you're in trouble. If its says you're rich, you might be okay and you might not.

-Xerxes