so before i swapped to DSM 450cc injectors (from stock 235s) everything was fine. fuel pressure chilled around 42-44psi, fluctuated slightly with throttle, but stayed. i have an AEM FPR installed with a gauge in the engine bay. walbro 255HP in the tank, and a VAFCII for ghetto fuel tuning.

this afternoon i did the swap, everything went great, car started right up (detuned to -48% all across the powerband), and i haven't thrown a CEL since. but like the title says, i'm having some weird problems.

1) driving around at medium to high throttle, there's a squeaking noise coming from the engine bay. it sounds like a belt rubbing, but since it started immediately after this swap i doubt it's a belt. plus by messing around with the throttle from the engine bay, it sounds louder near the FPR (not by the belts).

2) shitty idle and otherwise engine missing. RPMs will just drop randomly, both at idle and whatever driving speed.

3) my frigging VTEC crossover point changed. i have no idea how. i left the VAFCII to change it at stock settings, based on pressure/throttle/RPM/etc. so why the hell would swapping injectors delay my VTEC crossover? i don't get it.

 

aright...so VTEC engagement depends upon 5 things:
1) engine RPM
2) vehicle speed
3) throttle position
4) engine load (pressure at MAP)
5) coolant temp

i know exactly what RPM it kicked in before this swap (VAFCs act like VTEC solenoid lights if you haven't used them before), using 100% throttle, which was consistent in any actual gear (i think vehicle speed just means any gear other than neutral or reverse) and with the car warmed up (minimum coolant temp).

SO, that leaves pressure at the MAP sensor. if the problem were some kind of vacuum leak, it'd account for the shitty idle and maybe the random RPM drops while driving, too. WOT now has pressure at -1.0 or -1.1 psi, but i don't know what it was before for comparison. anybody? or any other theories? i still have no clue on the squeaking/squealing.

 

my idle is so bad that the engine stalls. nobody has any ideas?

 

with the stock injectors back in, everything works fine, like i expected. WOT has pressure at -0.8 or -0.9 psi, so not a whole hell of a lot different...but consistently different. VTEC is back to normal. i don't really get it.