Diablosport Forums

ok sio i have a 98 mustang gt
and when i try to lean the fuel a little or anything at that the inj pulse width gets all messed up im not sure if it is supose to but bank one will be at idle about 1,4 and bank two will usuaklly be about 3.4 or 4. 5 and only gets worse when you accelerate.
and it gets to the point where it has no power acts like its bogging but no matter what rpm if you go more then 3/4 throttle it stutters kjinda then goes but stillhas noticably less power.

also my fuel pump duty cycle is 100% this will be the 3rd fuel pump i have tried im on a 255 now
and the fuel rail pressure reads 0 psi

it seems liek it should be more then 0

if any one can lend a hand to why its like this it would be much appreciated
thanks

also i forgot my mods i guess
98 mustang gt

pi swap

o/r x pipe no mufflers

410 gears

k&n drop in

egr block off

solid mounts
5 speed
i think thats it im not sure lol

Check the FRPS, if it reads wrong, will do wrong things. do you get a P0190 code?

lito wrote:Check the FRPS, if it reads wrong, will do wrong things. do you get a P0190 code?

the what??
not sure what that is......
no codes i have the mil off but when i turn it on the light will come on but when you check it it says no trouble codes...but when you go to clear it it will clear.
before it use to get a emissions code something about low or no flow surge or purge solinoid i think... any ideas?

The "Fuel Rail Pressure Sensor" is the sensor that is bolted on top of the fuel rail, if it is not working well, the PCM will command more than needed fuel pump work to achieve desired pressure, if it goes wrong it usually flags the P0190 code, you should try to get what codes are getting flagged to pinpoint your problem.

i dont think i have anything bolted n top of my fuel rail. where isd it located.
i have a 98

ok i checked i have nothing bolted to the fuel rail
not even a place for anything like that

could it be a inline vacuum sensor or something

Oh, a 98!, sorry I misread that, there is no FRPS because they have a return fuel system. So the pump duty cycle and fuel pressure readings have no effect, pcm does not control that.

I would try to get a fuel pressure gauge into the system and check the readings with the vacuum of the regulator disconnected and plugged so there were no vacuum leaks, it should read about 40psi, low 30's with the vacuum connected and once on the road it should go and stay about 40psi on WOT.

luck.

it runs low 30's on vacuum and 40's with no vacuum i just checked it multiple times

the weird thing is i can use the diablo tune but when i try to adjust it is when it ghets all messed up so i dunno
any ideas?

stop messing with it if it is fine with the diablo tunes.you must be messing with stuff you shouldnt be messing with

ok well like said on here simple bolt ons work great with it but when you start modding it you need more and well im a little more modded then just bolt ons.


so if someone with alot of knowledge on this thing or 98's at theat could help it would be great i could really use some help


o and for dazzzy i am just moving fuel lean by one percent so i dont think its anything bad

so im gettin absolutely no support here

i would really like to get this figured out

What exactly do you need to modify? Do you have a wideband AF meter on the car? A K&N dropin filter should need little to no adjustment at all. If you did a PI head swap you may need to get with a custom tuning dealer as well if you are having detonation issues...

Kev

ok i do have access tyo a wide band and yes i am pi swapped
it just seems like there is more in it and i am tryin to figure out why when i try to lean it out richin it up or even change some timing it goes all crazy and makes the injectors run almost 100% duty cycle

invest a wide band you may may need to change to a adjustable fuel prssure reg.