A3m Ecu

5.0 HOtrain · May 27, 2014

Just bought a 89 GT motor complete (stock) and took the wiring harness and computer. My last car had the A9L ECU, this car had the A3M. I'm curious what is the difference between the two? My current car is giving a code that basically says the ECU is smoked and I was going to swap this into my 93. I have not pulled the kick panel off my notch to see which one it has, but have not heard of the A3M before, only the A9L. Input very much appreciated, thanks guys.

Shakerhood · May 27, 2014

I cant remember for sure but want to say the A3M was from an Automatic.

5.0 HOtrain · May 28, 2014

It was a 5 spd car I took it out of?

stykthyn · May 28, 2014

92-3 5spd mustang. Works just fine.

jAEded · May 28, 2014

I have that one in my 93 5 spd.

jrichker · May 28, 2014

Computer & interchange infomation
The Mass Air computers from 89-93 are interchangeable with a few exceptions. Just be sure you use the MAF & MAF sensor from the same series computer. The auto transmission computers use a different start circuit than the manual computers. You can use an auto trans computer in a 5 speed car with no problems or changes.I have done it in my original 89 Mustang GT, and I know it works OK. I have no positive input or comments on using a 5 speed computer in an auto trans car. I personally would not do it.

The odd duck is the 93 Cobra computer, labled X3Z which is interally calibrated for 24 lb injectors. Use the MAF & MAF sensor from the X3Z computer to avoid problems with the computer's internal calibration. Try and avoid the 93 Cobra computer if you can.

Some cautions about O2 Sensor harnesses need to be observed to avoid damage to the computer.
Only run a auto trans O2 harness with an A9P
Only run a 5 speed trans O2 harness with an A9L
See http://forums.corral.net/forums/gen...manual-auto-differences-year-differences.html for more O2 sensor wiring harness info

All the following are mass air unless they say Speed Density

8LD - MANUAL 88 5.0L Mustang Speed Density
8LF - Auto 88 5.0L Mustang Speed Density
A9L - 89-93 5.0L Mustang 5-spd Mass Air
A3M - 93 5.0L Mustang 5-spd Mass Air
A3M1 - 93 5.0L Mustang 5-spd Mass Air
X3Z - 93 5.0L Cobra 5-spd Mass Air internally calibrated for 24 lb injector
A9P - 89-93 5.0L Mustang Auto Mass Air
A9S - 88-93 5.0L Mustang California Mass Air
C3W - 89-93 5.0L Mustang Auto
DA1 - 87 5.0L Mustang 5-spd Speed Density
J4J1 - 94-95 5.0L SVT Cobra 5-spd
T4M0 - 94-95 5.0L GT Vert 5-spd
U4P0 - 94-95 5.0L GT Auto
W4H0 - 94-95 5.0L GT
ZA0 - 95 Cobra R
D9S - Lincoln LSC

5.0 HOtrain · May 28, 2014

Good information J, thank you. The car has 30# injectors and matching BBK maf meter (had stock on it when I purchased). I assume the 02 sensor harness is original and I have not pulled the computer out yet to see which one it has. I would assume the car has the A3M as it's a 93. I bought the car the way it sits and have been working out the tuning issues. It has old school edelbrock heads / intake and unknown cam. I was told it had been tuned, but again, won't know until I pull the computer.

The kid I bought the motor/harness/computer from initially said the car was an 89', however the black oil pan (only in 93 if I remember correctly-hyper piston motor also?) and years / computer numbers you sight above tell me otherwise.

jAEded · May 28, 2014

Could be a 89 with a 93 motor?

I have the X3z and my car ran pretty rich vs the A3M. Not sure if it was the comp or something else. Maybe I got a bad reman X3Z?

stykthyn · May 28, 2014

X3z is calibrated for 24 pound injectors. If you ran it on an otherwise stock 5.0 no doubt it ran rich.

jAEded · May 28, 2014

No, I know. I have FRPP bosch 24#s. Been playing around with X3z, A3M, C & L, Pro-M, and a tuner chip to find the combination that runs the best. So far its been stock A3M w/ Pro-M.

I actually thought the exhaust sounded better with the X3Z over the A3M.

5.0 HOtrain · May 29, 2014

So the car did have the A3M....I've never had a tune or seen a computer that had have one done, is this normal looking?

I swapped in the unmolested computer and car seems to be better......hard to tell after initial start up and idle w/out driving (already into the beers...lmao). I will know better tomorrow upon test drive.

stykthyn · May 29, 2014

It either had a chip at one point or it was a reman unit.

5.0 HOtrain · May 29, 2014

The car also has a non-stock fuel system on it that seems to consist of a fram HPG-1 external filter, Paxton A1100 fuel pump (identical pic below), and a fuel filter just prior to the fuel rails after the regulator. I changed the filter in the fram and pulled the filter off at the front of the motor. The fram on the inlet side of the pump was relatively clean and the fuel looked good. The other one however was hard to blow through and upon taking it apart the element looked like . With 40 psi I assume the fuel blew through it no problem, however I put it back together without the element.

Does anyone know what filter this is and where I can buy a replacement? There are no markings on the housing or element.......

I know little about the car as mentioned due to the fact the guy I purchased it from knew nothing.

5.0 HOtrain · May 29, 2014

The car had an old school Paxton (and possibly nitrous) on it at one point. The car still has all the brackets for the blower with the blower removed (head unit seized-car came with it). I have the brackets now to put the front of the motor back to stock minus the a/c and smog. I'm not sure if the tune in the car was for the blower or n/a? I made 303/332 rear wheel with my 90lx, stock bottom with AFR165, edelbrock intake, and Ed Curtis cam.........stock computer with C&L 76mm, tb, 30#, full exhaust, ect..........with no mods to the computer.

stykthyn · May 29, 2014

I am sure it was for the blower

A3m Ecu

5.0 HOtrain

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stykthyn

I want to measure mine. It doesn't look that tall.

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I want to measure mine. It doesn't look that tall.

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I want to measure mine. It doesn't look that tall.

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I want to measure mine. It doesn't look that tall.

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I want to measure mine. It doesn't look that tall.

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I want to measure mine. It doesn't look that tall.

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I want to measure mine. It doesn't look that tall.

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