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post #1 of 6 (permalink) Old 02-09-2004, 07:05 PM Thread Starter
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MAP vs MAF

I'd like to get a few things determined about the 3.8 NA's. I know for a fact that all 89-90 3.8 NA's have a MAP sensor, and all 91-97 3.8's have a MAF sensor. Now the question is -- Are the 89-90 MAP cars Speed Density? Or are they Mass Air? Because I have a have a source who says all Speed Density controlled vehicles made by ford stopped in 1988. A MAP read car with Mass Air does not seem out of the question. It wouldn't really work all that accurately, but could work. Now does anyone know for sure?
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post #2 of 6 (permalink) Old 02-09-2004, 10:39 PM
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There's no MAF on the 89-90 N/A cars. So, they can't measure Mass Air. And I think all that leaves is Speed Density.

(The S/Cs from those years had an MAF and an MAP, so they could measure Mass Air.)

You probably know this, but for anyone who doesn't, an MAF works by heating a wire to a specified temperature. When the airflow increases, the wire cools off, and more voltage is required to keep it at the correct temperature. This increased voltage gives the computer the signal that airflow has increased.

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post #3 of 6 (permalink) Old 02-09-2004, 10:49 PM Thread Starter
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But I don't believe they are speed density. Is there a possibility that the MAP works with a Mass Air ECM? The 'source' I was talking about was a ford engineer and said the Speed Density stopped in 88. I think it would be possible for the MAP to work with a mass air ECM. I know the computer can't fully adjust to changes when you mod the car a decent amount, but a chip can fix that from what I've read. So I believe it may not be Speed Density.
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post #4 of 6 (permalink) Old 02-09-2004, 11:01 PM
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Non-MAF (mass air) cars are speed density. MAF-equipped cars are mass air. Those are the two primary systems of air metering used by Ford fuel injection. The speed density system uses temperature, vacuum, and I believe TPS readings to determine via tables how much air should be entering the car under any given set of circumstances.

MAF computers and speed density computers are different, plain and simple. They way in which they interpret how much air enters the engine is just different altogether.

AFAIK, ALL fuel injected Fords have a MAP sensor. It does, after all, measure vacuum and serves as a barometric pressure sensor for the ECM. Even though it may not be as vital in determining air flow for mass air cars, it does tell the ECM what kind of load the motor is under when compared to TPS values.

I think that Ford did stop using speed density on the 5.0 motors in 88 or something like that so some people might get confused. I never understood why they used two separate systems on the SC and NA V6. Seems like they could have just written a different program for the SC mass air computer and used MAF/DIS on the N/As from the get-go. Such is life.

Hope that helps clear up some things.

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post #5 of 6 (permalink) Old 02-09-2004, 11:13 PM
 
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Josh thanks you saved me alot of typing. The 5.0 mustang did switch to MAF in 89.
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post #6 of 6 (permalink) Old 02-09-2004, 11:54 PM Thread Starter
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so then 89-90 3.8 NA's are MAP speed density. Thanks for the info. I thought this originally too, but after talking to the ford engineer I started questioning things. So the ford engineer is wrong then? That's interesting.
-Thomas

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