jabo3

ok

i have a manual 1997 cobra mustang

problem
for the last year of so it sometimes runs rough. it has started to become more frequent now.

the rough feeling is that of it is loosing gas or getting to much which causes it to misfire/stall and surge in rpm a little. the surge in rpm is mostly the revs going down at idle then going back to correct idle.

the car has had this problem once where it would not start back up and i had it towed to stang specialties in pompano cause this time it had actually displayed a check engine light however they put it on the meter thing and it read misfire and loose gas cap.

now it is doing it everyday. i know i got bad gas in the past from a crappy station off of griffin and i95. i put sea foam in it and it seemed to help.

tonight was probally its worst night i hit a small bump in the road with my rear end and suddenly it felt like is was running on 7 cyclinders and as soon as i went to give it gas it went really low in rpm and then when i gave it gas the car wouldnt do anything it was like the gas pedal was not working at all.. i turned the car off and then back on and it then the gas pedal worked again but still was running rough like.



things i have done to the car to try to fix it
new plugs
new coils
new wires
new iddle air control valve
oil change
cleaned the throttle body
cleaned mass air flow meter
new battery
new alternator
new fuel filter

none of it helped

im leaning towards fuel injectors,fuel pump, another new fuel filter and maybe pcm/ecu

oh and by the way john from specialties in pompano checked my fuel presure and it stayed solid


any help would be great




some of the mods done to the motor
air intake
msd coils
shorty headers "right header leaks a little"
fully worked heads from ronnie at stang specialties
removed imrc's or welded open
diablo hellfire chip




so my question is are the signs of a bad fuel injector?
bad fuel pump?
pcm/ecu going out?

any help would be great thanks?

redneck racer

Fuel injectors are a pretty cheap fix to have them sent off and flow tested. For around $140 you can get them flowing like brand new, and they will all be flowing the same. If that didnt cure it i would then lean towards the fuel pump, or the wireing to the pump. Possibly the FPDM could be going bad aswell. Sounds like a fuel issue to me. Did the car sputter and have issues while they were checking the fuel pressure? If not that wouldnt really tell you anything about whats happening.

uberstang1

Could be a maf issue, the reason it doesnt start right after is because its prob flooded with fuel

jabo3

okay update.....

ive had my car at he shop now for a few day. he couldnt get the cobra to act up so i went over there today and drove it about 1/4 tank of gas.

as soon as i pulled back into his shop it did it.

it was surging in rpm. went below idle rpm then up to 2,000 rom then back down to 500 rpm and finally stalled. when i started it back up you could smell a crap ton of fuel and see non burn gas in the form of smoke come out the exhaust pipe. the car quickly went back to normal idle. so we hooked up a laptop computer with a very expensive software program to it and couldnt find anything out of the normal.

I have a diablo chip on my computer so he saw some weird stats but i confirmed with diable that it was fine..

so then we wanted to test my fuel presure regulator.

tell me if i tested it correctley .

i put a fuel presure tester on my car at the fuel rails it read 30psi at idle. i then pulled the vacum line off the fuel presure regulator and the fuel presure went up to 40psa and then i put it back on and fuel presure went to 30 psi again...

does that sound like a correct test of the fpr?

so after that i drove the cobra around with the fuel presure gauge hooked to it for around 40 mins in stop and go traffic and it stayed around 30psi and didnt skip a beat...


is 30 psi correct for n/a cobra?

any help please im pulling out my hair and I really dont have much left

cobro2333

read on another forum a guy had same problem, ended up being the alt. sendin bad signal, he replaced and problem solved

badass98svt

I know this is kinda old, but I would re-replace the IAC and TPS, then reset the ecu.

SnowWhtSnake

I started having this same issue on my 96 cobra. Sounds like the exact same problem.
Did you ever find what was wrong. Mj_koester@yahoo.com
Thanks, Mike

SnowWhtSnake

I started having this same issue on my 96 cobra. Sounds like the exact same problem.
Did you ever find what was wrong. Mj_koester@yahoo.com
Thanks, Mike