I just ran a series of Diacom scans on my 94 Formula with the LT1. It's all stock and runs just fine. Everything looks"sane" except that all the block learns go back to 128 if I turn it off for a few hours and then restart it. They then work their way down to about 120-123 where they stabilize, same as always. Shut it down for just a few minutes and it retains them. Battery is good and I have no reason to think that the electrical system is screwed up in any way. I am only looking at the block learns when in closed-loop mode. I know that in open loop they read 128 under most (all?) conditions.

Thoughts/ideas/conjecture? Is there a memory in the computer that can go bad? Is this how it's supposed to work?

 

Scratch that- the PCM loses it's memory ANY time you turn the key to the "OFF" position for any length of time and then restart.

I checked all the fuses including one marked PCM/BATT (sounded promising) and they are all OK.

 

Unless you have an internal problem with the PCM, the obvious thing is you are losing power to your PCM when you ignition is off.

Lets start there.

GL!

Ben

 

I would if I knew where to look. I found some fuses that supply power to the PCM but they are both still good. Beyond that I have not a clue where to look to check somethign like that. Some pin numbers/locations to check for power with the key off would be great.