I was reading some of the other responses above and gustang818 had told me that my best bet for an ecu was from a 91-93.

gustang818...
do you know if part# is F2TF-12A650-AHA would be a good ecu for me? subford had mentioned that the vss input may be different?

 

I would give that one a try, especially for $25. My understanding with the VSS is that it always puts out 8 pulses per revolution and the computer converts that into mph and other data. If that's the case, the processor isn't going to care if it comes from a sensor in the trans or from the rear end. It respectively gets the signal from rpms of the tranny output shaft or the rear end.

I'm up north right now and don't have access to my list of processors but the -AHA suffix sounds right to my recollection. I remember -AHB as another ecu that would work. Once I get home tomorrow I'll check.

 

gustang818

Previous to 1992 the EEC stock computer assumes 8000 pulses per mile from the VSS.
Starting 1992 the F-series had 108 teeth on their Speed Sensor Ring. That came up to about 75,384 pulses per mile from the VSS.

Previous to 1992 the VSS sent its output strait to the computer.
Starting 1992 the F-series VSS output went to the PSOM and not to the EEC/PCM Computer and then the PSOM sent pulses to the EEC/PCM Computer after it played with them.

Is the PSOM a divide by 9 device that can adjust the pulses somewhat so that it still sends 8000 pulses per mile to the EEC/PCM Computer?

If so then a 1992 EEC/PCM Computer would work in a 1990.

I would love to find somebody that knows about this so it can be verified.

 

thanks gustang818 / subford. i will wait to hear back from you.

 

If you put in the $25.00 part# is F2TF-12A650-AHA and it works OK please let me know.

I intend to put a scope on both types and look at the input to the computer but it may be sometime before I get this set up and tested.

 

subford

i haven't bought that one yet because i was kind of trying to get a confirmation that it will work first. gustang818 said he will check into it today and let me know.

 

You definetly do not want to run the new motor with your old ecu. My first swap was for my brother when he shot the crank in his '93 302/AOD and bought a complete 302 out of a '96. He never seen the truck it came out of so we had no idea what tranny was behind it but the dude at the junkyard told him it was a "plug and play" WRONGGGG! . First thing after we did the swap was figure out that the wiring harness off the '96 was 1 number off from the '93 ECU therefore we could get tons of spark but no fuel, good thing the top end of the '93 was still good so after we had everything in the truck and bolted down we had to take the upper and lower intakes off and all the wiring harness (pain in the butt leaning under the hood) Install the '93 intakes and wiring harness on to the '96 block. BINGO truck started right up Still runs 3 years later with a hesitation and idle lope and gets about 10 mpg on a good day! It sounds like a timing issue and we went over every part of timing we could from changing the firing order of the '96 to the '93 to see if the ECU would be fooled into thinking the whole motor belonged in it. to practically twisting the distributor all the way around to find a "smooth" spot. Soooooooo to make a long story longer my suggestion is DO NOT TRY AND RUN A DIFFERENT YEAR POWER PLANT WITHOUT THE PROPER ECU.

 

Louis:

Subford is right about the PSOM being in between the RABS/VSS and the computer on the 92+ trucks and that it may pose a problem. I believe what Subford is saying is that if that signal that comes out of the PSOM is the same as what the 1991 and earlier VSS sent, there is no problem and you can use the later computer. However, if the PSOM sends a different signal to the computer than your 1991 and earlier VSS did, then the 1992 computer will not work. It will be looking for the kind of signal that comes from the PSOM. The question is (and what I don't know) what signal is sent to the computer after it comes from the PSOM. I can't tell you if the computer you are looking at buying will work without the PSOM, only if it is for a 302/E4OD. It is.

Sounds to me like you are on a tight budget. If you can't afford a $25 mistake, do not buy the 1992 F2TF-12A650-AHA computer. Ideally you would find a processor with the numbers F1TF-12A650-TA which is from a '91 truck with 302/E4OD. If you are willing to roll the dice, you could buy the '92 computer, try it in your truck, and post back with the results. Sorry I can't give you a definitive answer.

 

that's because the 96 was OBD2 and had 104 pinouts froim the ECU and pre-96 was OBD1 and has 60 pinouts from the ECU. You can't match up OBD2 to OBD1 and vice versa



Jim

 

gustang818

im going to try and find one from a 1991 as you and subford suggest. the one for $25 from the 1992 is the only one ive found so far close to what i need. its not that im on a tight budget, but to be honest i've spent so much time and money on this thing and im getting tired of it! i don't really want to keep buying parts unless i know they are right. i have a garage full of spare parts for this thing as it is! i will keep searching.

 

i just called a local junk yard, and they said that according to the exchange they have, the 90-92 will work? i may just try the one from the 92

 

I say give it a try. If it doesn't work right, stop using it and keep looking. As Barbara Stanwyck said in an old movie: “You take a chance the day you’re born. Why stop now?”

 

I know the harness off the '96 didn't work with the '93 ECU and either my brother will have to live with the crappy gas mileage and the hesitatin and loping or get rid of the truck because I don't see any way of getting a '96 ECU to work since there were no AOD's used that year or I don't think they even used the C4 that late in the F-150's

 

nope they were all either E40D's like mine or the 4r70W's




Jim

 

Countryboy: If you put all the 93 hardware and wiring on the 96 motor, the problem (hesitation, idle lope and 10 mpg) is not with the ecu. Have you pulled the codes?