ECM temp swap

[jrod92]

The ECM in my 94 Explorer is acting strange. Got out my Ford Shop Manuals and proceeded to go through all the troubleshooting tests. To my best deduction the ECM is stuck in limp in mode. The codes say no connection to MAF sensor and no ground to ECM from fuel pump. I ran all the voltage tests and ohm tested all the wires from the ECM plug to the MAF sensor and fuel pump. All test fine. MAF sensor 0.8volts at idle to 2.4volts at revs. Fuel pump steady 40psi at fuel rail, and dead heads at about 70psi. My question is, I have access to a ECM that is not Calif. aproved. Most likely won't pass smog. Its a F47F-12A650-MB. Mine is a F47F-12A650-DBA. Seems the DBA model is hard to come by. No one around here has one. All on back order. Yeah right. Does anyone know what the programing or parameter differences are between the two. I was thinking of trying the "MB" model until I can find a new "DBA" one. Any thoughts or suggestions would be great.

 

[awood]

I don't recall the numbers, but for mine I found an exact match on e-bay awhile back. There's more to it than just the part number. There's a "calibration code" which is (as I remember) the alphanumeric 3, 4, or 5 digit code in the larger type font on the label.

It's been awhile so I hope what I'm telling you is correct.

 

[Anime]

You should pull the cover to the ECM housing and look at the circuit board and the capactitors. It's very common for ECM's of this age to have damage to the circuit board from the caps leaking electrolyte on the metal traces and even onto the CPU connections. Ford used cheap capacitors for the ECM so they only last so long. This causes strange electrical issues with seemingly no effective fix.

The other ECU might work, but the differences between them are for things like transmission type and emissions, so they are generally not directly swappable with few exceptions. You do generally also want to match the large 4-digit "calibration" code above the part number.

Rockauto.com sells refurbished ECMs, as do auto parts stores like Advance Auto Parts.

You can also buy used on ebay or post a wanted ad on here, but a used ECM will likely develop the same capacitor leaks and damage if it doesn't already have it.

 

[jrod92]

awood, I did know about the cal code. Just can't seem to find a way to break the code.
I work with industrial electronics and it seems that everything has not only a base program but also adjustable parameters and special calibration codes. Augh!!!!

Anime I'm one step ahead of ya. I already pulled the cover and checked the mobo and all the components under my big magnifying glass. Even looked for pins that could have been cracked or come lose from the board in the solder tracks but it all looked ok.
Go figure. Rockauto has it on the temporarily not available list. The other places I checked were not in stock at this time and not sure when it would be available. I did find a place in Florida that reman most any auto/truck computer and seem to have a good warranty. So I filled out their order form with all the info they wanted. Supposed to come in about a week, pre programmed and ready to plug in and fire up. Guess we'll see. I already kinda miss drivin the ole gal. Kinda like an old pare of shoes.

 

[awood]

Found a listing on Google, but there's not much info there but a list of available codes. I saw a familiar code there. Mine was a VET1 for my 94 4X4 XLT auto trans, A/C. Here's the link:
http://oldfuelinjection.com/?p=17

 

[Anime]

If the caps are fully intact and there's no other obvious damage, I would think that disconnecting the battery overnight and then re-connecting it, starting the engine, letting it idle for 5 minutes, and then going for a drive so the ECM can start to re-learn would be the ticket.

Otherwise if the same codes persist I'd suspect some other electrical or wiring issue, maybe a shorted wire somewhere. If another ECM gives the same codes I suppose that would confirm it.


If nothing else, Rockauto shows the F47F-MB as being for the automatic transmission, the F47F-DBA just being for the cali emissions, also for an automatic transmission. It'd be a bad idea to swap ECU's for a manual trans into a vehicle with an automatic, but I'd think swapping to another automatic ECU would just affect the emissions, though it may affect other things depending what slight differences the 94's had between the cali emissions models and the ones in other 49 states, if any. Could be the ECM was the only thing making it meet cali emissions requirements and the F47F-DBA might make it run fantastic.

 

[jrod92]

awood, the f47f-MB that I had access to / now in my possession is a VET1. I couldn't stand it any longer and had to plug it in and try it. Hooked the batt. back up, hit the key and the ole gal fired right up. Let it set and idle for about 5 minutes or so and then took her for a 25 minute spin. went through town and even hopped on the freeway to come back home. Just purred right along as if nothin was ever wrong. Good response off the lights and on the on ramp. Shifts good, no jerking or hesitating. Once my new "Calif. Aproved" computer shows up I may have to do a comparison to see what the differences are as far as driveability, fuel mileage and such. If nothing else I'll keep this one on the shelf for a good backup unit.

 

[Anime]

Hey, if it works, it works. The only concern I'd have would be if making the engine run like it has Federal emissions when it actually has Cali emissions could damage anything long term, like the Cali-specific catalytic converters. However, I don't think the emissions were that complex or that the Cali models had anything else special the others didn't, so short term, it's probably fine. A backup ECM that works can be priceless, not just to get you out of a jam if something happens, but to troubleshoot and eliminate the ECM as an issue.