I am running HRC Stage 1, boosting bout 5 lbs, rebuilt Cartech fmu so it stays fairly consistent. I keep fuel pressure around 53-55psi at idle, I only have a mechanical gauge. I have a blinky a/f gauge and a apexi TT which I keep set on o2 voltage readings. Recently, I noticed that while at WOT, blinky a/f stays at rich and o2 reads around .92-.95, but then all of a sudden, the o2 voltage drops and the a/f goes showing lean. I kept it at this for a min and noticed that there was no surging or misfiring, no fuel cut, it didn't act any differnt at all. Vaccum is ok, idles fine, fuel pressure at idle is ok. This normally happens with 1st and 2nd, never higher gears. Any ideas? Is the o2 going, it is a bosch one after all, or is something else fawked?? thanks.

If it's not the o2 sensor then I'd say replace the Cartech. Hell, replace the Cartech anyways!

that crossed my mind, but I've never had any problems with it, and if I was really running that lean, I'd be getting fuel cut like a bitch, and I haven't.

Drove it around alittle more, I'll floor it, shows .95, then it will either just shoot down to .22 or it will tick down about .1v at a time. What could this be? Do I need to get an interior mounted FP gauge and see if my fp really is dropping or what?

do ya have an EGT gauge? if so what is it doin, if not get a new O2 sensor.
later
"Z"

nope, no egt gauge. Think its really the shitty bosch o2 acting up?

If I were you man, I'd sell that Cartech FMU and get a Vortech SFMU -- regardless of how your Cartech is acting...I just wouldn't trust it. Then get yourself an EGT gauge....tuning off of EGT's is my preference.

I'm thinking about, by the way man, kick ass sig, very nice.