91 mustang lx supercharged spitting and sputtering under boost
- Thread starter mpalank
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ShortThrow50
Member
yeah please post the following:
what injectors do you have
what fuel pump do you have
do you run a fmu and a btm or do you have a custom tune
How much timing do you run
What is your fuel prsseure
That should get you a little more answers
what injectors do you have
what fuel pump do you have
do you run a fmu and a btm or do you have a custom tune
How much timing do you run
What is your fuel prsseure
That should get you a little more answers
have a 306 edelbrock performer heads....f cam.....trick flow intake.....70mm throttle body,,,,,76 mass air meter ,,,,,30pound injectors.......have a 190 intake,,,,,,car has a fmu,,,,,,at idle its at 40 pounds of fuel.......when boost kicks in goes up to about 60 pounds,,,,,,the car has a stock regualtor in it.....no tune on the computer no wide band,,,,,,,some times the car will run its ass off and fuel pressure will hit about 70 pounds..then driving normal it will throw a check engine light and run like crap again.....i know its fuel jsut cant figure out the problem.......
7-UP BILL
Founding Member
tried changing gap been watching feul pressure it is only going up to about 55ps dhouls be a round 75 you would think......re did all vacum hoses on fmu did not change it at all.....i have a 190 intake fuel pump......stock fuel pressure regulater just ordered a new one of those this thing has me stumped,,,,,,,,,do you guys think i should eliminate the fmu and do a bbk inline pump.......so i dont have to worry about he fuel pressure any more.......air to fuel gauge shows the car going lean when boost arrives...im lost...
7-UP BILL
Founding Member
you may want to go to a 255 in tank pump. I had a problem w/ a 190 where the T-rex aux pump was sucking it dry. You need to have in tank larger than aux.
dont remove the FMU unless you get a custom tune done. without a custom tune the stock EEC is still trying to target AFR far too lean for a blower car, thats the job of the FMU to build up rail pressure real high to ultimately release more fuel.
you can throw the biggest pump in you want but it wont "give" you and more fuel.
all the fuel pumps job is to keep pressure at the rails which is determined by the FPR and it changes slightly according to vacuum pulling on it.
if your FP stays solid under RPM where the car is making alot of power your fuel pump is big enough. if you notice fuel pressure dropping under WOT at higher RPM, your fuel pump isnt putting enough out to keep the rails pressurized high enough.
as for the sputtering, when i had the vortech on my car i ran into missing and cutting out when under boost. i lowered my plug gap to .025 and it helped but didnt totally cure the problem. i put on an ignition box and it cured the problem, i then opened the plug gap back up to around .035-.040 car ran great and suprisingly picked up quite a bit from the ignition box at the power levels i was at.
you want to run as much plug gap as you can, this keeps the spark bigger and more efficiently burns the mix, but you have to have the strong enough ignition to keep up and not blow out or misfire.
good luck.
you can throw the biggest pump in you want but it wont "give" you and more fuel.
all the fuel pumps job is to keep pressure at the rails which is determined by the FPR and it changes slightly according to vacuum pulling on it.
if your FP stays solid under RPM where the car is making alot of power your fuel pump is big enough. if you notice fuel pressure dropping under WOT at higher RPM, your fuel pump isnt putting enough out to keep the rails pressurized high enough.
as for the sputtering, when i had the vortech on my car i ran into missing and cutting out when under boost. i lowered my plug gap to .025 and it helped but didnt totally cure the problem. i put on an ignition box and it cured the problem, i then opened the plug gap back up to around .035-.040 car ran great and suprisingly picked up quite a bit from the ignition box at the power levels i was at.
you want to run as much plug gap as you can, this keeps the spark bigger and more efficiently burns the mix, but you have to have the strong enough ignition to keep up and not blow out or misfire.
good luck.
thanks guys for the feedback what type of igintion shoul i get for the car,,,,,the car itself did not have a secondary fuel pump just bought a bbk 1602 should be in here a couple days the fuel pressure is only jumping up to about 50 55 pounds and the aor to fuel is running showing lean under boost..........any more feedback would be awesome thanks
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