early MAF swap for a late MAF ???

90blkbrd

Registered User
A 1990 Thunderbird has a 55 MM MAF and 30 LBS injectors,
and a 1994 Thunderbird has a 70 MM MAF and 36 LBS injectors.

I have read that the MAF is calibrated to injector size.

Here is the kicker, I have read that these MAF's are interchangeable.

Is this true and how is this possible?

Experts please step forward.
 
the MAFs are not calibrated, and there is a difference in some models from 89-95. If you don't mind not being precise, go for it. But it's not going to be anywere near a perfect transfer function.
 
FastSC said:
the MAFs are not calibrated.

Please explain this... If MAF's are not "calibrated" then how come cars run rather strange when MAF's for 19lb calibrations are used in cars that have 24's or 30's?

In some Ford models the EEC had the different calibration to compensate for different injectors, but not sure about the SC's.
 
90blkbrd said:
Anyone else willing to give a more detailed answer?
Well, as I understand it, the 92/93's had a 70mm MAF CALIBRATED for 30lb injectors. The 94/95's had a 70mm MAF CALIBRATED for 36lb injectors. So you could put a MAF from a 92 or 93 on your 90 and get some benefit from it. You could also put a 94/95 MAF with 36lb. injectors on your car and get even more of a benefit. I don't know about any MAF's that don't need to be calibrated. :confused:
 
FastSC said:
the MAFs are not calibrated, and there is a difference in some models from 89-95. If you don't mind not being precise, go for it. But it's not going to be anywere near a perfect transfer function.

There are two ways to "calibrate" an MAF. One is through changing the sampling tube (C&L) and one is through changing the electronics (Pro M). Neither is perfect and neither method applies to any factory Ford MAF meter.

Ford used 2 different MAF housings on SC's and other Tbirds. They are the 55MM and 70MM. Other than that there are no physical differences on any Tbird MAF's. Not sure about Mustang MAF's, but they may be the same also. What does vary from application to application are the actual electronics in the meter. Some have different outputs than others and they are matched to the EEC that they came with. It is advisable to use your stock electronics as they are a sure match for your EEC. Any deviation there is going to be subject to some risk.

In a general sense, Ford MAF meters are NOT calibrated to any specific injector. The injector parameters are in the EEC itself. This does not mean that all Ford (or even Tbird) MAF signals are the same, just that the "calibration" that people keep referring to, doesn't exist.

So, in summary, there are two different housings, several different MAF transfer functions (tied to the electronics module), and no different calibrations. (which, I believe is exactly what FastSC said above. :) )
 
I just did the swap for the 92 MAf in my 90.

It does seem to feel slightly quicker, and slightly noticable at the boost guage...

So should I swap the electronics back to my old MAF electronics or what???

Thanks!
 
OK..

Get this

the 89-92 55mm Tbird SC meter is IDENTICAL to all 89-93 mustang 5.0 GT meters..Electronics...And housings..the 93-94 SC 70mm mass air is IDENTICAL to the 93 cobra mass air.

All of these mass airs are 100% interchangable with one another. There are also other ford meters interchangable as well.

89-93 5.0 stang has 19lb injectors
93 Cobra has 24lb injectors
89-93 SC has 30 lb injectors
94-95 SC has 36 lb injectors

So what gives?..I know Ive personally mentioned this a billion times.
Ford calibrates for injector size in the EEC...Not at the meter itself.
Being you are swapping factory mass airs for one another you will not have a problem. The minute you change injectors you most definately will.

You cannot add a 94-95 SC mass air and 36lb injectors in an 89-93 car as it will NOT WORK.
 
Good enough.

So if I were to use 94-95 MAF and 36lb injectors, I would need to put this EEC tuner to some good use...

Thanks!
 
Damon, you are mostly correct. However, the actual output of some of the MAF sensors are different and the OE Ford MAF transfer functions reflect this. The only way you would know which one is what would be by downloading the MAF function from different processors with an EEC tuner or other such device. I also know this from personal experience that there are some MAF SENSORS (not the meter housings) that read QUITE different than others and switching them will result in a badly wacked transfer function.

:)
 
That's good to know. So if you buy a 73mm C&L MAF that is calibrated for 30lb. injectors and put it on your car, are there any concerns that one should have? :confused:
 
Darkside said:
That's good to know. So if you buy a 73mm C&L MAF that is calibrated for 30lb. injectors and put it on your car, are there any concerns that one should have? :confused:

It'll be fine.
 
DamonSlowpokeBaumann said:
Dave thats due to the EEC..Not the meter itself
Actually I've seen the transfer functions and some are different. Just to be clear, it is not the housing that causes the differences, it is the electronics. They are "calibrated" the same in terms of injector size, but the sensor outputs voltages are different. The car will run either way, but with some sensor electronics the AF will be way off. Most are the same or very close, but since there is no good way to tell which are which, stick with your original ones for best results.
 
Listen guys. It's like this. Both the meter and electronics effect fuel delivery per any injector size you put on the engine. It isnt the injector "size" that depicts the amt. of fuel being delivered, the number (ex. 36lb) is just the amt. of fuel the injector is capable of flowing. It is the amount of air which passes through the MAF "sampling tube",(via the sampling tube is part of the calibration) by way of cool are passing over the 2 wire "hot" and "cold" sensors, in-turn providing a specific voltage to the EEC which then decides the injector width (the amt. of fuel provided for the voltage reading of the amt. of air entering the MAF). The cooler the air, which would explain larger sampling tubes because the air is read as being more cool the more that enters the tube, the less resistence the signal wires on the MAF sensor have, therefore providing more voltage for a larger injector width. There are many charts to follow, which will give you a voltage reading in coordance with the amt. of fuel that will be delivered by the injector as a result of the voltage reading. In short, the MAF, injector size, MAF sensor, and EEC all work together to controll fuel delivery, but it ALL starts at the MAF. It works as a small computer before the computer. Hope this helps
 
However, the sensors are limited in their readings, that is why most people say it is the electronics that strictly effects fuel delivery..I have found the most effecient means of tuning, believe it or not is the Super AFC by apexi. That thing works wonders, and it's half the price of a damn chip. I dont know if anyone has tried it besides me, but for anyone looking to keep their factory MAF and trying to open up the sampling tube by way of a shortcut...if you're going to do it be sure to use a 15/32" drill bit with a press to do so. It seems to run a little on the rich side at WOT, but man it works wonders over stock variations through-out the RPM range, and it's cheap.
 
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