Will a fuel pressure reg make my injectors "bigger"?

[OrangeMustangGt]

i know i need larger injectors, but im saving for a supercharger. Then i will upgrade to 42's. For now, i was wondering if i can get some more fuel out of my injectors by raising my fp? I aready have a 255lph pump, and woudl raising my fpr in effect increase my injectors size? thanks

 

[S/CBlack95GT]

Yes.

 

[Black70Fastback]

basically, yes. and actually if you tune it right. you could probably get away with that as a permanent fix. unless your WAY off

 

[HISSIN50]

do remember that the EEC IV is adaptive. if you increase pressure, initially it will run 'fatter' but eventually the puter will trim it back down as much as it can (often times compromising other functions in the process).

 

[stang_gt_1994]

Injectors are made to operate at 43 psi. You can get them to put out more my upping your fuel pressure will only be a quick fix. Also by doing so you will also cause you pump to pump less fuel. Read the new MM&FF and you will see what I am talking about.

 

[S/CBlack95GT]

do remember that the EEC IV is adaptive. if you increase pressure, initially it will run 'fatter' but eventually the puter will trim it back down as much as it can (often times compromising other functions in the process).

Not true. The computer will change the A/F ratio under part throttle b/c the O2s are active. Under WOT the computer has a set A/F ratio it is set to maintain. However, if you increase the pressure the engine will run richer and the computer has no idea since the O2s are not active. It is for this reason that these cars are so simple and great to modify/tune.

 

[HISSIN50]

Not true. The computer will change the A/F ratio under part throttle b/c the O2s are active. Under WOT the computer has a set A/F ratio it is set to maintain. However, if you increase the pressure the engine will run richer and the computer has no idea since the O2s are not active. It is for this reason that these cars are so simple and great to modify/tune.

right, so for WOT it can help. but during 95% of driving, when not at WOT, i myself prefer to have the injectors working at a higher duty cycle (since the increased pressure will shorten the duty cycle at non-WOT runs).

i totally see your point - im just saying why i said what i did. i dont think i run WOT as often as most (nor do i have a power adder), so my perspective is different than most.

 

[Grn92LX]

The eec CAN adapt at wot. Sometimes changing FP is a temp fix and sometimes its not. Stock FP is 39psi.

 

[mo_dingo]

You are right that the computer does trim fuel at part throttle if you up the fuel pressure.

I can't say anything definate on WOT though. I read through my eec-iv book and I couldn't get anything definate.
Scott

 

[OrangeMustangGt]

whell, if it trims the fuel, that is good right? i mean it will try to get it to the a/f ratio at part throttle. Right now, i know i need more fuel, and was thinking this is a good way to do it.

 

[Rootus]

The EEC actually makes adjustments at part throttle, but it will apply whatever it learns to all throttle positions, including WOT. It may be using tables to tell it what A/F ratio it wants, but it'll be using KAMRF (long term fuel trim) to tell it how to get that A/F. So FP is going to be a temporary fix, IF you are using it to get a richer mixture. If your injectors are not big enough, and you're running lean, then upping the fuel pressure will allow them to flow enough fuel for the EEC to compensate and get you the correct A/F ratio.

Dave

 

[Black70Fastback]

it will work. like they are saying. your computer, using your o2s, will adapt. it will shorten up the duty cycle.

so at wide open throttle you need 105% right now but obviously it cant go over 100 and you will fall lean. if you fatten up the pressure. the injector will only need 95% duty cycle to supply the same fuel. and 95% is possible.

i think some of the other responses think you want to richen the car up. your just trying to get it to not run out of injector on top end.

after you adjust the pressure, it will run too rich for a couple of days till the computer compensates. and you do want it to compensate.

 

[SN95Oh]

what I heard if you make the fuel pressure to high, it will mess up the spray pattern

 

[Grn92LX]

Too low and it'll hurt the spray pattern.

 

[johnf440]

The eec will not "adapt" to FP at WOT, like a previous poster said. It will indeed adapt at part throttle - but just pull the battery cable and reset the EEC so it will learn the new part throttle mixture anyway. Trust me on this - people have been doing this for 15 years with great success, and with the EEC IV, it works great.

Think about it, with the idea of WOT adaptive, the FMU from superchargers would have never worked because they just kicked fuel pressure up in relation to boost....

My 2c

P.S. Without a dyno with wideband O2, your are pissing in the wind buying injectors or adjusting fuel pressure. Get a regulator on it and get it on a dyno if you are concerned. Spending 3-400 dollars here and there willy-nilly makes no sense at all and I would say that 50% of the people that purchase 24lb injectors for their mustangs did not need them, they needed another 400 dollar bolt on...

 

[OrangeMustangGt]

do you think i need them with my car?