I got a 1992 F250 with a 5.0 V8 and E4OD trans. I've been posting about having starting issues in the cold. I've replaced nearly everything but this post isn't exactly about that. What happens is it runs like it's on 2 cylinders until it warms up. Once it warms it runs very well and strong. I've changed ECT, plugs, cap, rotor, coil, O2, Fuel system is practically new and tested fine on pressure, IAC, and then some. But Tonight I had an issue. I didn't let it warm up enough and it was still running sorta rough. So I left and it would cut out very badly. It almost sounded like the trans went from 4 to 2 over and over. I shut it off at the store, came out and started it. It ran rough for a few seconds even though it was at operating temps. So I made it home but it ran better with few misfires. I drove it this morning after letting it idle for 10 minutes and it never did that! So I went to check codes once I got home. I ALWAYS got 512 and 625. 512 was usually continuos. I followed everyones directions cleared them but they came back. 625 disappeared a few times though. so this is my problem: KOEO I got 111 and in continuous I got 512. no 625 this time. SO I then did KOER I started it and instead of flashing 4 times the check engine light just came on. WHY?? Is that a bad PCM? Or should I wait awhile? It eventually went off. I tried it multiple times and it would go into test mode. Main question is . Why did the check engine light not flash and just come on?

 

**Update** I unhooked the battery and let it sit for awhile. I went out, hooked it up and warmed the engine and now it works. I got my codes. KOER was 111 but no continuous codes came up. I didn't even see the quick flash. Is this normal? but the KOEO came back with 635 then continuous code 512 like it has been for awhile now. Strange thing is when I got home with it jumping around I got 111 and continuous 512. no 635. But now i got it back again. I didn't drive it too see if it's cutting out but i'll do that tomorrow.

 

DTC 512 can be triggered by disconnecting the battery. It simply means the PCM detected a loss of the Keep Alive Memory voltage. Some PCMs seem more sensitive than others for whether or not that code is triggered by removing a battery cable.

You can clear the codes by removing the ground jumper or your code reader when the codes are in the process of being displayed. This would eliminate a falsely triggered code 512.

DTC 625 indicates an opening in the EPC circuit. That would explain your transmission "It almost sounded like the trans went from 4 to 2 over and over" issue.

 

Ok thanks! Well I went out this morning to start it and I started crappy like usual but once it warmed up it was fine. I drove it and it acted fine. I got home and checked for codes. Engine off I got 111 and continuous 512 but no 625. I cleared them and went to try the engine on test. Once I start it, few seconds later the check engine light comes on and stays on. It won't do engine run test. I drove it again and did engine off test, this second time I got the 625 and continuous 512. But still no engine run. I unhooked the battery for now and I'll let it reset itself. Maybe that's what it needs?

 

I had gone out to try again. This time the light flashed 4 times but after that the motor had a miss and it jumped out of KOER mode. But I may know a possible issue. I may be low on coolant by a slight bit. My guess is maybe during the flash mode when the engine starts to change RPM a air pocket might be hitting the sensor causing to jump out of test mode. Is that a possibility? Or does this sound like a bad PCM?

 

That is a pretty far fetched theory. I would say it is very unlikely the coolant level is causing the issue.

 

But what could cause it to do that? A bad PCM? I don't know why it's jumping out of it like that

 

I would say you either have very bad wiring and connections or a bad computer.

 

X2 Thanks Bill!

 

Very true! Because I always did the KOEO and KOER just fine until the other day when I was gonna remove the PCM. I wanted to remove it to check for damage and dirty connections because of codes 512 and 625. Ever since is when I had this issues I believe. I didn't know i had to lower the fender well to do this so I out it back in because it was late at night. I couldn't get it out from the kick panel side. I seen someone post that but it's impossible

 

No way to do it from the inside on your '92. The earlier trucks had access from the inside. Bill has a photo of it.