converting to 24lb injectors

1995GTStang · Dec 21, 2009

I know most of you have probably answered this question 100 times.

My question is...I am doing a Cobra convert to my 95 GT. I am currently running a 302 .30 over with GT40 intake and GT40P heads. Along with a F303 cam, 1.7 roller rockers, SCT chip, BBK shorties and cold air intake. I think I am surpassing what these 19lbs have to offer.

On my research I have found that 94-95 Cobra's have the same MAF sensor as a GT. It is the PCM that is setup for the 24lb injectors? Every where I read it states that the MAF sensor is what you need to change or tune on any increase in injector size. But I have noticed that both the Cobra and GT use the same MAF sensor with a Cobra being 24lb injectors.

Any tips?

revhead347 · Dec 21, 2009

You can actually do it one of three ways. You can buy a MAF that is recalibrated for 24lb injectors, which fools the computer. This is the recommended way, because it's affordable, and you get a bigger MAF too. A bigger MAF probably isn't necessary right now, but may be nice down the road if you do further mods. You can get a piggy back chip for the computer which readjusts the computer directly for 24lb injectors. This costs more than the MAF, but you can also get other performance enhancements done on that chip included in the price. Or you can go to a Cobra computer, which is not recommended, because it's a huge hassle, is expensive, and really doesn't do anything for performance.

Kurt

SableSal · Dec 21, 2009

What color are the 24lb injectors? I hear Ford color codes them. Also what size MAF are we talking about here? Or should the size not matter, but what car it came off of?

Great information! I'm planning on upgrading when I get the GT40 Explorer intake setup.

Thanks!

revhead347 · Dec 21, 2009

24s are blue.

Kurt

Adam95GT · Dec 22, 2009

SableSal said:
What color are the 24lb injectors? I hear Ford color codes them. Also what size MAF are we talking about here? Or should the size not matter, but what car it came off of?

Great information! I'm planning on upgrading when I get the GT40 Explorer intake setup.

Thanks!

Aftermarket is the only way to do just a maf and injectors.... C&L , ProM etc. They use different size sample tubes to kind of make your car think its getting less air so it injects less fuel with the bigger injectors a stock maf is a stock maf...

2002BLGT · Dec 22, 2009

Adam95GT said:
Aftermarket is the only way to do just a maf and injectors.... C&L , ProM etc. They use different size sample tubes to kind of make your car think its getting less air so it injects less fuel with the bigger injectors a stock maf is a stock maf...

And by tricking the computer , it throws off the load calculations and that will cause all kinds of headaches , possibly pinging under load and other issues , any reputable tuner will tell you to not use a calibrated meter on any 94-up mustang , this guy already has an SCT chip , his best bet is to get the chip reburned for the 24lbs injectors , a larger MAF is only going to benefit someone pushing over 400HP ....

Adam95GT · Dec 22, 2009

i was just talking to the guy i quoted really... with a tune you should pretty much use a stock or lightning mass air and have your tune take care of adjustments... alot of tuners hate cars with calibrated mafs...

was just trying to state you cant go grab a "cobra" maf and slap some 24lbers on the car and have it run right...

302Feen · Dec 22, 2009

If you don't already have that combo put together, be SURE to check PTV clearance with that cam and 1.7 rockers. You're going to cut it real close on the clearance.

But yes, you will want to upgrade to the blue 24# injectors with that combo. And just get an aftermarket MAF calibrated for the size injectors.

The MAF is the cheapest and easiest way of switching injectors.

The Cobra and GT use the same exact MAF, but the Cobra's computer is tuned for the 24's. Our stock MAF's are actually 75mm in diameter, but there is a solid post in the middle that is about 5mm wide, whic is why they consider the Cobra/GT MAF's to be 70mm. So the stock MAF is actually plenty big enough, but an aftermarket MAF won't have the post in the middle which will allow better airflow.

2002BLGT · Dec 22, 2009

he has a chip , the OP's cheapest way to upgrade to 24s is to get his chip reburned for the 24lbs injectors

revhead347 · Dec 22, 2009

2002BLGT said:
And by tricking the computer , it throws off the load calculations and that will cause all kinds of headaches , possibly pinging under load and other issues , any reputable tuner will tell you to not use a calibrated meter on any 94-up mustang , this guy already has an SCT chip , his best bet is to get the chip reburned for the 24lbs injectors , a larger MAF is only going to benefit someone pushing over 400HP ....

The C&L uses different size sampling tubes, the PMAS is calibrated specifically. People have been compensating for larger injectors with a different MAF for 2 decades now. It works just fine.

Kurt

2002BLGT · Dec 23, 2009

revhead347 said:
The C&L uses different size sampling tubes, the PMAS is calibrated specifically. People have been compensating for larger injectors with a different MAF for 2 decades now. It works just fine.

Kurt

exactly because back in the day that was the only option because there was not a way to reprogram the computer , so they did a hack job way of doing things ......not taking into consideration what other things it throws off specifically load calculations , foxbodies dont have this problem because they have a WOT spark function that prevents the spark from being thrown off during WOT conditions , 94 and up cars arent so lucky , fuel and spark are both load based so tuing the computer is the proper way to adjust for the injectors .....

302Feen · Dec 23, 2009

Yeah, having the chip reprogrammed would be the cheaper way. But buying an aftermarket MAF will kill two birds with one stone.
1. it will enable him to use the larger injectors
2. it will flow a little better than the stock MAF due to the aftermarket piece not having that bar straight through the middle.

revhead347 · Dec 23, 2009

2002BLGT said:
exactly because back in the day that was the only option because there was not a way to reprogram the computer , so they did a hack job way of doing things ......not taking into consideration what other things it throws off specifically load calculations , foxbodies dont have this problem because they have a WOT spark function that prevents the spark from being thrown off during WOT conditions , 94 and up cars arent so lucky , fuel and spark are both load based so tuing the computer is the proper way to adjust for the injectors .....

That's absolute hogwash. There are thousands of Mustangs out there with different size MAFs and Injectors, and they run absolutely fine.

Kurt

2002BLGT · Dec 23, 2009

revhead347 said:
That's absolute hogwash. There are thousands of Mustangs out there with different size MAFs and Injectors, and they run absolutely fine.

Kurt

Believe what you want , but you need to read up

http://www.fordfuelinjection.com/files/A9L_vs_T4M0_showdown.pdf

revhead347 · Dec 23, 2009

Just saying, if you put a calibrated MAF in there, it will work fine. Countless people have done this, regardless of the differences in the computer.

Kurt

1995GTStang · Dec 23, 2009

I will just have the chip updated. Later I will buy a larger MAF and TB unit to allow for more unrestricted airflow into the engine.

I appreciate the responses and ideas....it has given me some insight on the next few steps I am going to take

Thanks all

final5-0 · Dec 23, 2009

Just a thought or two from my corner

Kurt has a point here about something that works

Willie talks about the load factor getting all outta whack

That is very true :Word:

I won't go into a lot of details
but
Like a lot of things with these Stangs

You see our two year run (94-95) get thrown in with the Fox Bodies

Thats just not something that should be done in this instance

Fox pcm's are rpm based while ours are load based

Our Stangs use load to arrive at fuel/spark values
and
Guess what tells the pcm load amount ... Meter

Here is something to keep in mind

The cheat method of matching meter/inj will hose the load factors
in our pcm's but 24's don't make it as inaccurate as if you go 30 or
larger size inj's

So Yeah ... doing that with 24's is not like it should be
but
Most of the time ... It ain't off enough to make it not work

Again ... what works fine for a Fox don't necessarialy mean it will work
with no issues when talking about our Stangs

Grady

2002BLGT · Dec 23, 2009

Grady the point I am trying to get across is that when people see post like Kurts they think thats all they need to do no matter what the case is

This creates confusion and frustration when they put them on the car and then have issues and refuse to believe its the meter/injector thats the problem, they think if one person can do it then well lets put a 347 stroker and AFR 185 cnc heads and huge cam and 42lbs injectors and calibrated meter and wonder why the car wont even run ....

All anybody needs to do is read the article I posted and they should have a better understanding of why they should TUNE the car , not try to skimp and not tune it when its said and done the tuning can accomplish WAY more than just get the air/fuel ratio right , but the advantages of controlling the timing , getting rid of the tip in spark retard , on automatics you can adjust the shift points for early shifting when higher rear gears are installed , adjust the cooling fan temps and alot more ......

revhead347 · Dec 23, 2009

I just get frustrated on this website sometimes. Sometimes I swear I'm on a Honda website. There are a lot of people on this website that think the only way to make any mod work is to trailer a car two states away to a reputable tuner, and drop $700 on a dyno tune.

Kurt

2002BLGT · Dec 24, 2009

revhead347 said:
I just get frustrated on this website sometimes. Sometimes I swear I'm on a Honda website. There are a lot of people on this website that think the only way to make any mod work is to trailer a car two states away to a reputable tuner, and drop $700 on a dyno tune.

Kurt

Did I say that? NO I did not , this guy already has a chip so thats why I am telling him to get it reburned , its a simple change that would take any tuner less than 5 minutes

I tell people to tune it themselves and help I guys with email tunes with Moates stuff and Tweecer users as well .....as well as making new templates over on tuneexchange , with the tuning stuff that is out there for the 5.0s there is no reason someone should even have to run a calibrated meter even on a foxbody

converting to 24lb injectors

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