4.0 swap automatic not going into OD

[jeiroq]

Let me start off by saying that I've been working on my 4.0 swap for far too long. I've ran into all sorts of problems. First, the engine I got that was supposed to be "good" had black gunk in it so it had to be rebuilt. After finishing that and finally getting it into the truck, we found that the transmission was really bad off and needed to have it done.. that alone took about 8 months because the guy we had doing it ran into all sorts of family problems. Now I finally got it running, engine runs amazingly and it has plenty of power but as I was doing a highway test I found that I couldn't go over 55 without sounding like an angry beast.

From what I've read, I should've grabbed the tranny from the donor vehicle as well.. I didn't do this and have already rebuilt the '90 Bronco II A4LD with heavy-duty parts. What can I do to get OD to engage? Or is it supposed to have engaged (engine and computer from '93 Explorer) already? I've read that I could possibly need to dummy something? I'm really needing this fixed, and fast as this is my only vehicle.

 

[BroncoDan]

It's my understanding that the 90 BII A4LD should be the same as the 93 Explorer. I'm in the middle of the swap myself. Having had limited time to work on mine I feel your frustration. Hopefully somebody will come by soon with a definite answer.

-D

 

[jeiroq]

Well I've been told that there's a difference with the electronics of it. The one from the Explorer is told by the ECM when to lock-up the torque converter and switch into overdrive. My girlfriend's dad worked on it with me yesterday (Ford mechanic for 20+ years) and he asked if I was wearing my bullet-proof boots because I may have shot myself in the foot. Without the torque-converter lockup it's a death sentence for the A4LD, and no OD means no speeds over 55, preferably 50.

I've read that there's a way to get this to work, but it seems like nobody knows how to do it.

And from what else I've read, they changed in 93.5 to some more computer controlled stuff.. Anyone know what to check for on the ECM to see what year it really is?