I’m am trying to find a new ECM for my 86’ 302 5.0. E6TF-12A650-K1A. I can find replacements that end in KA but not K1A. Can anyone tell me if the KA replacement will do the trick or do I continue trying to find my needle in a hay stack. The reason I am replacing it is I have replaced just about everything on the fuel system I can replace. New pumps(all 3), tanks, filters, reservoir selector switch, injectors, coolant temp sensor, EGR, complete distributor, fuel regulator, plugs , plug wires, checked for grounded wires. I am getting a code 31(EGR valve position sensor out of range)). Truck starts when cold but but won’t stay running then will not start again. Fuel pressure is 41lbs. I am no mechanic but my brother in law who is has been helping me with it and he is stumped. All he can think to do is replace ECM but I can’t find an exact match.

 

To answer your question about the ECM, K1A and KA are as close to an exact match as you'll find. Those suffix characters are denoting revisions, probably just a code tweak. My '86 truck, manufactured 10/85 has a A1A suffix. Your truck probably has a much later date of manufacture. I would not be afraid to replace my A1A with a KA. Both still perform the same basic functions.

These computers are known for crapped out capacitors. There are three inside this unit. Their job is to keep the power flowing smoothly to the computer systems. They can be replaced if you are experienced with de-soldering and re-soldering on a circuit board. Three new capacitors cost about a dollar. Or you can just throw another new part at the problem.

Have you tested the O2 sensor?

 

Thanks for the information on the ECM. Not sure about the O2 sensor but I’ll check that out before ordering the ECM

 

Did you change the EGR position sensor? The EGR is two pieces, the EGR valve itself and then the position sensor on top.

You also have the EGR vacuum valve that actuates the EGR. Do you have vacuum on the EGR line when that valve is actuated? The computer sends voltage to the vacuum valve to open the EGR, and then it quickly looks at the position sensor to see if it moved. So there are several things that can go wrong on that system. The valve usually has a plastic cap you can take off with a foam filter under it. This filter likes to get clogged. When the computer wants to shut the EGR, it turns the valve off, but when that happens the valve has to let air into the EGR line to get rid of the vacuum. This air comes from that foam filter.

 

FWIW, I found that if you take your truck to a mechanic that has been around for many years, they normally know these old trucks pretty well and can fix or work around any issues.

I have a local guy that has a big repair shop and knows old cars and trucks well, He repairs just about anything from new cars to old 1960's trucks, there is always interesting things sitting outside his shop. Bus's, old RV's, big dump trucks, etc.

I'm not sure how long your friend has been working as a mechanic. Just putting this out there.

 

you're lucky because finding someone who knows vehicles pre-computers and is good, is getting to the point of finding hens teeth.
Or getting old timers disease like my buddy who can't recall much anymore.

 

I find that hard to believe. I can see in some Metro areas and big city's may be, but here in CT there are still a lot of older mechanics and long time well established shops.

I'm 67y/o, still use the trusted mechanic my dad used back in the 1980's when I came back from the military, my son uses him too. The local auto motive machine shop, my oldest sister went to school in the late 1940's + 1950's with his father. In the town I've been living in since 2010, there's a guy at the local junkyard that comments on my truck every time I stop in. He has one and an 82 dump truck. I even have a Body Shop buddy that is part of the local network.

I would think, even in the mid west and southeast, "if you ask around" you can find someone who can help and may become a trusted contact.

 

https://www.car-part.com/cgi-bin/search.cgi

I searched the junkyards for you. 86' F150 4x2, 5.0L AOD tranny.


www.car-part.com you can fill in your request.

 

ok believe what you want. assume what you will.

 

There is the ID number marked on the part...and the actual part number:

E6TZ-12A650-KA .. Processor Assy / Marked with ID number: E6TF-12A650-K1A or E6TF-12A650-K2A

Rock Auto has remanufactured processors.

 

welcome back @NumberDummy I haven't seen you around for a while, was hoping all was well.

 

Two things:
That the vehicle starts when cold and runs then quits when it starts to get warmed up. When the truck starts cold the computer is running in open loop. A fixed, rich fuel mixture. As soon as the O2 sensor heats up it generates a signal voltage. The ECM sees this and switches to closed loop reading data and reacting accordingly. Is the problem an open loop/closed loop issue?

The code 31. Assuming you have only pulled KOEO codes since the truck doesn't run long enough to do the KOER test, the code 31 means the EGR valve position sensor is sending the ECM a voltage of less than 0.2v. Since you replaced it, seems like you have a wiring issue. Easy to test. Your potentiometer type EPS has a three wire plug. With key on, engine off the orange wire has about 5v. The brown wire should have about 0.5v. The black wire should be grounded to ECM, probably pin 40, maybe pin 60. If you don't have 5v at orange, check the orange wire at the TPS or MAP, they are all fed from the same pin 26. Got 5v? Do you have 0.5v on the brown wire? No? Bad EPS. Yes? See if you have the same 0.5v at pin 27. NO? Wiring. Yes? ECM problem.

Another way to check wiring is to perform the KOEO test with the EPS unplugged and the orange and brown wire jumpered. This will send the full 5v reference voltage back to the ECM. The self test will see the higher voltage and report it by generating a code 35, EPS voltage high.

 

Just thinking out loud...

How does the ECM respond if no signal is received from the O2 sensor? Would the computer switch to a default input and/or stay in open loop mode? I realize new fault codes would be generated if the O2 sensor was disconnected, but maybe the engine would run better. If so, that would indicate the O2 sensor (or some other sensor) was supplying an erroneous input.

 

With no signal, the EFI stays in open loop. When my truck had a bad O2 sensor it started fine but as it got warm and stuck in open loop it started to run badly. As it got a bit warmer yet, it quit. The plugs would be sooty in this case. A good running engine with thermactor (air pump) system operating properly will switch to closed loop quickly. The thermactor generally times out after only about one minute. IIRC, the ECM switches the air to the rear cat shortly after the O2 sensor starts generating voltage.

 

It's not ideal, but these engines should run ok in open loop. When they can't fuel the engine from the O2 sensor, they revert to open loop and fuel the engine from fuel tables located in the ECM memory banks. While not perfect, it should still be good enough to keep it going, albeit with a check engine light if your truck has one.