Hey guys,

I've done pretty much everything I can think of, but my car still runs lean at anything above 4-5 psi. Once it leans out, it seems very slow on boost so I know something is wrong. I've searched and searched on this subject, but can't seem to pinpoint what it is. Here is what I have done:

-New Fuel Filter
-Took off FMU and put on a friend's, but still leans out
-Thought it could have been FCD's, but have tried 2 different kinds and still leans out
-New O2 sensor

I just can't seem to figure out what it can be. I guess it could possibly be the fuel pump, but I don't know if that is a logical choice or not.

Please help me, I don't want to keep spending money on stuff that isn't the culprit.

EDIT:
Guess I should let you know what I have. I have a Walbro 255 and Vortech FMU on stock injectors only running 6 psi tops, but I have lowered the wastegate down to 3 and it stays rich on that boost level. Anything above 4-5 though and it leans out and is very sluggish feeling.

Mike D
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