[freebird]

i have a 2004 mustang gt that has a few bolt-ons. i have hi-flow fuel rails, 32lb. injectors, 75mm t/b, cai, and slp loudmouth cat backs. the car does not run well at all just wondering if there is anything i can do to solve this problem? i have a diablosport predator tuner but dont really know wat to set it at. any ideas would be helpful. thanx

[01KnightRiderGT]

to mm

Damn bro, were do i start their could be so many things wrong.

What exactly is it that it does?

[freebird]

well first of all when you start the car it revs up to about 2400 rpms and thats where it idles. im thinking that is from the t/b that i put on. but the bad thing is when i upgraded the fuel system it acted like it was flooding out all the time. when you drive it doesnt have any power and it sputters allot. i have long tube headers and o/r h pipe and am going to get a new manifold soon. should i try to get it dynoed or can i just tune it with the tuner i have?

[01KnightRiderGT]

Holy shit it idles at 2400: o

I would first check were the idle screw on the throttle body is set at.

With the car off, remove the intake tube, and see were the butterfly on the throttle body is at, it should be almost closed.

It might also be your IAC

Is there any CEL?

[yellow04GT]

Put your stock inj. back in, you don,t need 32lb. inj. with your mods. Inj. will not give you horse power they allow you to stay in a afr when your mods make too much horse power for the stock ones.

[freebird]

the idle screw is the first thing i checked but that wasnt it. do you guys know what size stock injectors are? i accidentally threw the old ones away. and do the high flow fuel rails help at all?

[01KnightRiderGT]

Originally Posted by yellow04GT Put your stock inj. back in, you don,t need 32lb. inj. with your mods. Inj. will not give you horse power they allow you to stay in a afr when your mods make too much horse power for the stock ones.

^ that also

[00vabchgt]

bigger injectors and high flow fuel rails won't make more power, they just support it. the high idle could be your IAC, sputtering could be becaues of the long tubes. i had some issues with mine when i got them put on. i got a good dyno tune and it fixed the issues for me. are you throwing any codes/ CEL?

[01KnightRiderGT]

the stock injectors are 19lbs

[dcook_14]

Did you get your car tuned for the bigger injectors?

[freebird]

how much horse power are the stock injectors good to?

[00vabchgt]

the stock ones are plenty to support your other mods. i'm making 275 hp/ 310 tq on stock injectors and not even close to maxing them out. you'll be fine for a while unless you start playing with spray or FI...

[Bullitt5339]

Originally Posted by 01KnightRiderGT the stock injectors are 19lbs

Not on an '04....

I believe the '04 had 21lb injectors stock.

OP, I would almost bet that those injectors are your problem, especially if you're not running a custom tune with them. You can change the injector size in the SCT, I would guess you could do the same in the Diablo, but it's just simply too much injector for your mods. The engine just can't use that amount of fuel, and can't back the fuel pressure down enough to make it run decent without it going all crazy.

The amount of horsepower isn't really a set number, it depends on a bunch of factors, but with 21lb injectors, you could run well over 300rwhp, which is every bolt-on with cams. The only reason to change injectors or MAFs on these cars is when you run out of fuel for your mods.

If you run too big of an injector, you're usually stuck with a car that won't idle well, low rpm power sucks, and generally just makes a car that's not happy, especially down low.

[dcook_14]

Originally Posted by dcook_14 Did you get your car tuned for the bigger injectors?

Still waiting for an answer

[freebird]

no i didnt get a tune for the big injectors yet i might try to find some stock injectors for it tho

[ajm]

Have a tune for the bigger injectors or did you just slap them in and call it good? If you dont have a tune for them im willing to bet money thats your problem.

[1stimeford]

Originally Posted by Bullitt5339 Not on an '04.... I believe the '04 had 21lb injectors stock.

24lb injectors on the '04....

[mell0]

i have a set of stock yellow 19# injectors that i'd be willing to sell if you're interested. PM me if you want to buy them.

[01MGGT]

I ran 42lb injectors with my car before the blower with jsut bolt on's and cams. All in the tune I say throttle screw is the cause if you already selected the injectors int the tune. You should check your TPS voltage. Should be around .96 with the throttle closed.

[Bullitt5339]

Originally Posted by 1stimeford 24lb injectors on the '04....

ummmm, no............

Pink injectors which are 21.5lb/hr......