24 lb injectors with stock maf?

West Texas Z said:

Crap. So I can keep my 19's and get a bigger MAF and be good?

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Yes, but the maf has to be calibrated for the 19's

West Texas Z said:

Crap. So I can keep my 19's and get a bigger MAF and be good?

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You should be good with the stock injectors anyways . . . unless you have enough other mods to make well over 300 hp . . .

SetofAces said:

You should be good with the stock injectors anyways . . . unless you have enough other mods to make well over 300 hp . . .

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Not that I'm doubting you guys but why do they sell the MAF's to match the injectors?

Mustang 75MM Mass Air Meters for 24Lb Injectors at LRS - Same Day Shipping!

The reason for all this confusion is that the aftermarket MAF manufacturers have totally FUBARED the meaning of 'Calibrated' (<--- Notice the intentional use of ' ', as what the aftermarket does isn't technically a Calibration... it's more of a Skewing of output. I will refer to aftermarket meters as 'Calibrated', and to Ford meters as Calibrated. Ford did it right, and the aftermarket does it the lazy way.)

A MAF meter measures intake air. Air flow is the input, and the voltage output is solely dependent on air flow.
ONLY an aftermarket meter is 'Calibrated' for use with a specific Injector size AND ecu combination.

For example -
A MAF meter 'Calibrated' for use with 30Lb Injectors on a 93 Cobra (X3Z ecu) is not the same as a MAF 'Calibrated' for use with 30L Injectors on a 90 GT (A9L ecu).

When using aftermarket meters, all three things need to be in harmony.


Ford did things a little different... Actually, you could call it the 'Right Way'
Ford Calibrated the stock ecu to read the output of the MAF meter used on that vehicle series. This is done with a setting called the MAF Transfer, which can be thought of as a way to translate MAF voltage output back into an air flow number (CFM or Kg/Hr).
There are 2 settings in the ecu for the Injector size, called the Injector High Slope and Injector Low Slope. Basically, this setting tells the ecu how much fuel will flow from the Injector for each millisecond the Injector is open.


The problem with the aftermarket MAF meters is that they skew the output for air flow, in order to trick the ecu into adding the right amount of fuel. This would be fine if ONLY the injector duration were changed based on MAF output.
However, the ecu uses LOAD to decide how much fuel and Ignition Advance to run, in addition to deciding what strategy to run. Load is calculated based on MAF meter output.
Introduce error into the MAF output, and you are introducing error into the LOAD calculations. Error in the LOAD calculations is carried over into the Fuel and Ignition Timing.


With the availability of the QuarterHorse from Moates and Binary Editor software, there isn't any reason why anyone should be running a 'Calibrated' MAF meter these days.
For roughly $300 you can be ready to tune & datalog nearly every parameter on your Fox Mustang. Changing injector sizes involves changing roughly 5 parameters in the ecu settings, and doesn't involve BUYING a new MAF meter.
Just my opinion though...


jason

The aftermarket MAFs modify either the MAF sensor or the airflow across the sensor. That tricks the computer into metering the
correct amount of fuel for the "measured" airflow. This isn't as good as the Ford method, but it is portable and will work
across a number of different engine combinations.

Ford used a much more sophisticated method in the 93 Cobra by writing the computer's fuel to airflow lookup tables to match
the fuel delivery of 24 lb injectors.

jrichker said:

The aftermarket MAFs modify either the MAF sensor or the airflow across the sensor. That tricks the computer into metering the
correct amount of fuel for the "measured" airflow. This isn't as good as the Ford method, but it is portable and will work
across a number of different engine combinations.

Ford used a much more sophisticated method in the 93 Cobra by writing the computer's fuel to airflow lookup tables to match
the fuel delivery of 24 lb injectors.

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ok, so if I install the 24's in my car (reason is that I'm getting a GREAT deal on a set) which MAF and throttle body would be a good combo for me that would get the best HP? 70mm throttle body + 76mm mass air?

Sorry for all the questions. ????

West Texas Z said:

ok, so if I install the 24's in my car (reason is that I'm getting a GREAT deal on a set) which MAF and throttle body would be a good combo for me that would get the best HP? 70mm throttle body + 76mm mass air?

Sorry for all the questions. ????

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Yes, or bigger...

the point of my long winded post was that 'calibrated' MAF meters are OLD technology, and not the best option available.
A 90mm LMAF will satisfy your current needs, and 'almost' any future upgrades.
They can be found for less than $100, shipped...
$250 for tuning hardware from Moates.
$110 for the Software to tune it from EECAnalyzer.

Roughly $460, and you will also be able to manipulate Fuel Tables, Timing Tables, Disable Emissions, Adjust Decel Fuel ShutOff, Account for Displacement Increases, Tune for best acceleration, etc......
But the coolest thing is... you would NEVER have to buy another 'calibrated' MAF meter again!!!

Long term the cost effectiveness of a tuner is worth it...

vristang said:

Roughly $460, and you will also be able to manipulate Fuel Tables, Timing Tables, Disable Emissions, Adjust Decel Fuel ShutOff, Account for Displacement Increases, Tune for best acceleration, etc......

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Yup, I agree.

But, as I often say, I deal with reality. And, in reality, there are total idiots like the one that posted a "for trade/sale" in the tech forums today. Sigh! IMHO, that's reality. Also, in reality, people want simple ricer answers, they do not want to learn or think.

So, let people slam their cars 2+" and adjust their TPS. Yup, their car will out handle and out run my car.


That's also why, if/when I give a rat's *ss , I tell people that want to go to 24's to get a 93 Cobra EEC and 93 Cobra MAF, keep the stock air box, and be done with it! It works, it's correct, it's simple, and it's cheap.

Of course, people run their POS C&L with their ricer cone filters and love it! So, if they are happy, that's what really counts.
Well, off the soapbox #1.


Okay, on soapbox #2.
If anyone really gives a rat's *ss about how real-life EFI control systems work, then I strongly suggest the following articles:

IMHO, the following two articles are a must read for anybody that wants to talk about MAFs.
http://www.fordfuelinjection.com/files/How_MAF_works.doc

Ford Mustang | MustangWorks.com - EEC-IV Adaptive Control. Your best friend or your worst nightmare?

BTW: Mike Wesley was well known in the racing circles (late 80's) and created the first "tuner software/chip of the EEC by reverse engineering the code.


Also, check out,
Ford Fuel Injection Strategies

A Quick Overview of the Inner Workings of the EEC (Mustang Fuel Injection Computer), by TMoss:
http://www.veryuseful.com/mustang/tech/engine/EECIVInnerWorkings.pdf

Technical Reference for the EEC IV.
http://www.veryuseful.com/mustang/tech/engine/eec-IV-Tech98.zip

Well, off the soapbox #2.



As some people know, I've been designing, specifying, and doing the architecture for critical precise control/response systems for a over a dozen years. I have my MS in CS/EE/CE (with a minor in ME) and I used to teach Control Systems engineering and DSP classes.

So, I know how even some engineering students and many engineers have a hard time understanding control systems.


IMHO, in reality, the vast majority of people that read this thread, and go to bigger injectors, will throw on some POS setup. I hope they don't forget to adjust their TPS to 0.9999v. This year, I went the whole winter with only one tank of gas with my Stang (I never had to add any gas at all!).

Oh yea, did I mention that people like simple ricer answers and do not like to think. HONESTLY, I didn't have to add any gas to my Stang this winter! Do not think, it will hurt!

That's also why, if/when I give a rat's *ss , I tell people that want to go to 24's to get a 93 Cobra EEC and 93 Cobra MAF, keep the stock air box, and be done with it! It works, it's correct, it's simple, and it's cheap.

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I cant get a Cobra EEC becuase I have an automatic.