[eric93stang]

I recently installed ford motorsport 24 lb/hr injectors and a 75mm PMAS mass air meter calibrated to the injectors. The engine is a crate engine from ford motorsports. It has GT-40 heads, E-303 cam, Trickflow Street Heat upper and lower intake, 65mm throttle body, BBK cold air induction, 75mm mass air sensor, underdrive pullies, headers, and an x-pipe.
The problem is the car seems to be running way down on power. The idle is steady at ~700rpm, but runs rough. When I try to give it some gas the car will hesitate and then rev. Also when coming to a stop the car sometimes dies. I have the timing set to 12 degrees and the fuel pressure set to 40psi.
Even though I have the mass air calibrated to my injectors, does the computer need some time to learn the new components? Does anybody have any advise for me?
Thanks!

[vtecwho]

you have made many changes to you car that you ecu is NOT designed to handle.

its hard to tell you if there is a mechanical problem with your car but i but you i could make it run much better if i could plug a tuning tool into it such as the tweecer.

you car most likely needs a tune.... sorry, but expecting to add as much as you did to your car and expecting it to run is gonna be hard.

if you are not familiar with tuning you have altered your throttle body airflow, helps with idle stability, MAF, and fuel. and many more......

the "calibrated" mafs are a joke without being able to tune it. it is just fooling the ecu into thinking there is a different amount of air coming into the engine so the ecu adjusts and takes or adds fuel to allow the car to run.

welcome to the world of after market mods. its a cause and effect deal.

you get a new engine..... it WILL need a tune to run right. tune = money.


try putting you old maf and injectors back in to see if the car runs better.

clean you old maf, the IAC....idle air controll..... and recheck the spout connector for timing purposes and any vacuum leaks.

let us know... good luck

[mustangfan1990]

Originally Posted by vtecwho

you have made many changes to you car that you ecu is NOT designed to handle.

its hard to tell you if there is a mechanical problem with your car but i but you i could make it run much better if i could plug a tuning tool into it such as the tweecer.

you car most likely needs a tune.... sorry, but expecting to add as much as you did to your car and expecting it to run is gonna be hard.

if you are not familiar with tuning you have altered your throttle body airflow, helps with idle stability, MAF, and fuel. and many more......

the "calibrated" mafs are a joke without being able to tune it. it is just fooling the ecu into thinking there is a different amount of air coming into the engine so the ecu adjusts and takes or adds fuel to allow the car to run.

welcome to the world of after market mods. its a cause and effect deal.

you get a new engine..... it WILL need a tune to run right. tune = money.


try putting you old maf and injectors back in to see if the car runs better.

clean you old maf, the IAC....idle air controll..... and recheck the spout connector for timing purposes and any vacuum leaks.

let us know... good luck

Just to let you know a stock a9l computer is perfectly capable of handling those mods. My engine had similiar mods but mine was more aggressive ( ie AFR 185cc heads, trickflow stage 2 cam) I had the same size injectors and such and my car UNTUNED ran 8 flat in the 1/8. You problem sounds like your MAF sensor. Try cleaning it. I would try and find another MAF sensor calibrated for 24s. When I first got my 24 pound injectors I had a stoc kMAF from a 93 cobra that worked really well for a temp MAF sensor. You can get those get at Autozone too. A N/A motor that Mild doesnt need to be tuned. Not saying it would hurt cause it would be good for it but not required. Try unplugging your MAF sensor and see if it makes a difference. how new is the MAF sensor and where did you get it. COuld be if you bought them used from a person they could have lied or the sensor is bad. I would nee more info though but almost 1000 percent sure your problem lies with your MAF sensor

[vikingpower]

put your old injectors and MAF back in, run the car and that will allow you to determine if its really the MAF or not.

I have a Boss/CHP Dominator 302 in mine, runs great with 30lb injectors and a C&L73 meter. And the stock '89 computer of course. All you need is some patience and attention to detail to tune it within 90% of what a shop or chip will do.

[eric93stang]

The mass air meter is brand new and calibrated to the 24lb/hr injectors. The car ran good before I installed the new injectors and mass air meter.

I was working on it the other day and noticed a hissing sound coming from the engine after i tried to start the car. I noticed there was a fuel leak coming from the fuel injector/fuel rail connection. Im gonna reinstall the injectors and hopefully that fixes the problem.

Thanks for the advise. I'll let you guys know what happened. Hopefully that works and I dont have a bigger problem.

[ShortThrow50]

Originally Posted by vtecwho

you have made many changes to you car that you ecu is NOT designed to handle.

:

i dont really beleive that. these cars rarely need a tune for anything man

[Foxfan88]

any mustang could benefit from custom tuning, not saying it would be alot, but i bet your could pick up a few HP from a tune on that car...

if you want to keep the 24s on the car you need to have the EEC's binary changed letting the ECU know what its injectors are flowing and put the correct MAF transfer in the there to match the meter you have....

dont fall into the hype that all you have to do it throw on the bigger injectors and run the "calibrated" meter, that isnt they way to do it. it needs tuned for them there is no way around it, if your wanting the best drivability and power.


IMHO, i would throw the stock injectors back on, stock injectors will handle that combo fine IMO. not even worth a tune at the power level your at...

and i have a C&L 73mm maf meter (uses stock MAFS and sample tube for 19s...) i ran it on my car N/A with 19s and it didnt seem to affect drivability at all. i guess the meter came close as far as the maf sigals going back to the EEC.

PM me if you interested i can sell it to you cheap.....


the only time when the tune really needs to be address is when you increase CID of the engine or a radical HCI engine making alot power. a blown engine also needs tuned as fuel and spark needs greatly change....

[eric93stang]

I fixed the fuel leak that i found. I started the car and then tried to set the timing to 10 degrees. I pulled the spout out and the car instantly died. I put the spout back in and, after trying a couple of times i started the car when i floored the gas pedal. I noticed before doing this the fuel pressure gage would flutuate a couple of psi up and down. When the gas was floored the needle would stay steady at 40 psi, where the fuel pressure is set.
After a couple of times of doing this i eventually was able to slowly let off the gas and the car was idling. I let it idle for a few minutes then got in the car and tried to give it a little gas. This made the car instantly die? I am confused, the injectors and the mass air sensor are brand new and they should be good. What am i doing wrong?

[vristang]

Put a vac gauge on the intake... it sounds like you have a leak.

A pulsation in the vac signal could cause the fuel pressure to pulse.


Did you do ANYTHING else under the hood when you installed the injectors & MAF?
What ecu are you using?


jason

[eric93stang]

I also added the adjustable fuel pressure regulator when i added the injectors and the mass air sensor. I also replaced the lower intake manifold gasket, but nothing seems to be leaking.
As far as the computer i am using the stock computer. The car is a '93 Mustang GT.
Why would the car die when i took out the spout to set the timing?

[mustangfan1990]

Originally Posted by eric93stang

I also added the adjustable fuel pressure regulator when i added the injectors and the mass air sensor. I also replaced the lower intake manifold gasket, but nothing seems to be leaking.
As far as the computer i am using the stock computer. The car is a '93 Mustang GT.
Why would the car die when i took out the spout to set the timing?

Sounds liek a vac leak. The idle should drop when you pull the snout to a really low idle and if you have a vac leak that may be to low for the engine to idle. That is the only thing I can think of