about to tune my car... but my fuel trims are maxed out ... PFC HELP

[((sr)) kelly]

so when i got my car tuned with the 2871r i maxed out my fuel trims up top...

the injector maps are at 149 across the board.. so my question is how do i get more fuel to the engine?

im prettttty sure all i have to do is increase the percentage of my injector from 50% (i have 740cc) and then take out fuel from the fuel trims... does that sound right???

[S14DB]

Isn't 50% for 550's and 100% for 740's?

[defiantmofo]

no 50% is correct for 740s, 550s is 66% if i recall correctly. are you running an adjustable FPR?

[((sr)) kelly]

nope.... i should probably get one lmao...

but my injectors are only at like 69% dc so there HAS to be a way to get more fuel into the engine.... i think i may be running really rich up top

[S14DB]

Are we talking about the injector duty cycle or the base correction?

[frosti108]

i would try upping the fuel pressure for sure. stock fuel pressure and running 740cc??? whats the point

[Def]

Why would you run higher fuel pressure than stock on a large injector?

...and why are you trying to tune your car without a wideband O2 sensor? You have no idea what your AFR are without one.


I would ensure your PFC settings are correct, as it sounds like something is drasticly wrong if your injector scaling coefficient is right and you're maxing out your fuel table.

[((sr)) kelly]

im not blind tuning... im not messing with anything off the fuel table... i just remember last time i got it tuned the tuner said i maxed out the fuel table so i was wondering if i could get more fuel in there by lowering how much i drop the injector %... like from say a 50% to a 45%.. then i can take away fuel from the table in the lower rpms.. will this work?

[frosti108]

Why would you run higher fuel pressure than stock on a large injector?

maybe im wrong... its my common sense telling me that if hes already running a big arse 740cc, the next logical step should be to turn the pressure up if he hasnt already.

its just in my head that an aftermarket FPR or FMU is standard equiptment for high performance. :loco:

[S14DB]

maybe im wrong... its my common sense telling me that if hes already running a big arse 740cc, the next logical step should be to turn the pressure up if he hasnt already.

its just in my head that an aftermarket FPR or FMU is standard equiptment for high performance. :loco:

No, it's a bandaid for not buying larger injectors. Increasing the psi will put stress on the injectors.

We need a FPR cause most fuel pumps(walboro) output at 50psi when stock is 43. The stock fpr can't handle this and fails.