n4ynu1010

Hello and I hope someone can help solve this issue I have
I got this truck 6 years ago, motor and everything but transmission was worn out, had motor rebuilt and literally replaced everything but the Alternator LOL
Motor ran very weak, had to come off line at 3000+ and feather the clutch and still would buck or die
So after a bit more diagnostic work I found it was the ECM, all other emissions controls IAC, TPS, IGN Module, Distributor, Cond. Coil, Evap Coil, Compressor, PS Pump, 2 of the 3 fuel pumps, rotors, calipers, axles, seals, drums, wheel cylinders, exhaust etc were all DOA leaking, frozen, failing etc..
The Truck had 266K on it, was given to me so I knew what I was getting into here LOL

So I sent ECM to have bench tested and it was bad also, the company that bench tested it rebuilt it and returned it, installed and vroom, truck ran, idled fine but very weak.
So I re-checked timing, wires, dist., module, cap and rotor all new, timing was good, looked for vacuum leaks, none found, check fuel pressure on rail and verified regulator (new also, original was pouring gas past diaphram) was working correctly for fuel pressure, all good.
So I was very perplexed.
Then I found out that this truck has the HO motor in it and the ECM had been replaced before so my replacement was, from what I have found, WRONG.
So I call the dealer and get OEM ECM # which is E8TF-12A650-AJ1 / AJ2
The dealer gave me my info from the VIN # 1FTDF15N5KNB61377
and from the Cal Code # 8-53F-R10
I talked with Cardone 2 years ago (2 hours) and they told me from the OEM ECM # I needed a A1 78-4790, not the A1 78-4688 that was in it that I had tested and rebuilt.
So I took the one I had rebuilt and gave it to O'reilly's as a core and purchased the A1 78-4790.
A1 78-4790 is a E9TF-ARA
A1 78-4688 is a E8TF-AJA, AJB

Now, after installing this different ECM, the E9TF-ARA version, the Truck runs wonderful, backed it into the road and took off as I had been and smoked the tires, has great power and torque, no more bucking or hesitating.

So here is my problem, Cardone says they have no cross reference for the OEM E8TF-12A650-AJ1 or AJ2, they say they do have a cross for the E8TF-12A650-AJ1A or AJ1B.....................BUT it crosses back to the ECM that was making the truck seem like it had a 1.5L 4cyl in it................................

And then when I give them the # for the one that is in it now it does not cross to my Truck at all, of course this is a different Rep 2 years later so maybe he does not know how to use the software ?????

No one seems to know about this HO 5.0L motor or have any listing for it to discern between the two in regards to the ECM's, but one Rep at Cardone 2 years ago knew and gave me the 78-4790 # as a direct replacement for the OEM #, and then this guy today is just lost in the sauce and real happy to get off the phone even though he could not answer my question.

I know there is someone out there that can help me, do I have the HO motor, or did someone change the motor, and though the ECM is working very good it would seem, it is listed as a "AT" application which should not really matter since I do not believe the '89 AT was electronic anyway, I would just like to know if I have the right one in it as if not, maybe it would run even better still ?????

Can someone please help, I would be forever in your debt, this is the first Ford I have ever owned, and I do like it, it is a beast with a 8' + bed and runs very nice even though I think it would be better with newer computer FI or just go back to a carb, but EPA rules ....................but even though it does run strong and is faithful as any truck I have had, just do not understand why it is so hard to get a straight answer on this ECM issue, it's like no one knows the HO motor exists, and as far as I know it may not be the OE motor, just really confused, Please Help Me
*I could pull some casting numbers if needed if I knew where to look, but the guy at the dealer told me it was a HO motor, he saw it in person, but not sure how he found out, the only fact I have is that the alternative ECM makes it run like it should, the other was like I said, like I had a baby 4 cyl under the hood, changed to the different one and wow, it ran like a V-8 was actually under the hood.

Thankyou

Guy