Originally Posted by
L1FTD
Cant see the tune right now, but AFR looks good. A small torque loss around 2500, then spiking up. Pretty much how the engine torque shows in the scanner, but this is on a dyno? Could be a sign of something, but the AFR doesnt show it.
Those fuel flow modes were a nuisance for a while, was sure it had something to do with that. Full throttle, I would always switch from low to normal around 2600rpm.
Turns out, the flow mode switch doesnt affect the problem. Annoying coincidence? Or GM knew there was something going on at that RPM and made the switch happen there? Who knows?
Ive run the car up with pressure locked at 300kPa, 350, 400, 450, 500. No flow mode changes, static pressure. Was doing this to better dial-in the fuel pump trims.
Lean spots are there at every pressure. They get richer with lower pressure, but not gone.
I still think its FSCM, or a physical fuel issue.
If its FSCM, may only be certain P/N?s affected.
Even in the threads on other forums (different cars) discussing a similar lean issue, its not every car experiencing the pressure/pulse resonance. Bigger injectors certainly highlight the problem though.
If I could get an FSCM code to trip and disable the pressure test, could at least rule that out.