my car keep leaning out between 3800-4000 rpms. when it does i can feel the engine loose power. in 1-3 gear, reguardless of throttle position. 4th and fifth gear are OK as long as the throttle is more than about 35%.

as far as my fuel system, i have a 255 lph pump(rewired) and i just put a new fuel filter on. i even tried raising the fuel pressure to about 60psi but it didn't help.
my O2 sensor is almost brand new. put on a new MAP sensor.
the only codes that come up are for my EGR, which i don't have and cat(gutted).

all data on the scan tool seemed okay except the timing advance was 35. is that normal? the advance at idle was good (12-13).

could i have a bad knock sensor? will i get a DTC if it is bad?

we need a little more info about the car
fpr, sfmu, ??
turbo?
injectors?
engine management before an accurate diagnostics can be determined

Originally posted by baxsom
we need a little more info about the car fpr, sfmu, ?? turbo? injectors? engine management before an accurate diagnostics can be determined

ok. i disconnected my SFMU and hooked back up the stock FPR, turbo's not on right now, but 8.8:1 block is in. stock injectors. i disconnected the MAP wires to my AFC and now have them strait from MAP to ECU. no EGR, no EVAP emissions, gutted cat, no A/C or PS

so your running a 420a with an SFMU without disabling the stock FPR on the fuel rail??

Thats your problem IMO. Do you have a fP gauge hooked up the the schreader valve on the rail? Is the FP rising with boost?