I thought I had a bad prom socket in my 8746 ecm because when I put in the latest chip iteration, I noticed an intermitent ses light and engine cut out under any kind of acceleration.Before this chip swap, 15,000 miles of trouble free driving with about 20 chips burned by me. I tried numerous other chips and had the same problem. I got another 8746 used that I pulled myself , and I am having the identical problem with the new ECM. ( when I installed the new ECM I DID NOT disconnect the battery)

The ECM will store codes if I unhook sensors. The car starts and idles fine. I don't think it is an ecm issue but maybe I got a bad one with the identical problem or installing it with that battery hooked up caused a problem.

I have checked the tps, map, circuits per GM service manual and they check out fine. Fuel pressure is in specs, the injectors are both working.
The only other thing I can think of is a ground and it was a concidence that it happened when I put in the chip. I am studying wiring diagrams to trace grounds.

I know this is not a prom question exactly, but I would sure like your thoughts as to weaather this sounds like an ECM/prom problem and I have missed something, or I need to move on to other things.

Thanks very much for your thoughts............stumped bob

 

So what code(s) does it set when you get the intermittent SES light?

John

 

Are you using a computer that is linked to the net for your chip burning?. If so one of the softwares your running have have updated and fubar'd your prgramming. Try Alt Contrl Delete and exit everything but explorer, and your burning program and see if the changes anything.

Some parts houses have a break out box. Where you plug in a box where the ecm goes and it reads all the sensors. Might try hooking one up, and shaking all the wiring to see if something is loose.

Unplugging or not unplugging the power to the ecm shouldn't make a difference since eventually you have to apply power anyway. Just do the final plug in with key off.

 

Thanks for taking the time to resond guys. My ECM is not setting any codes. It just flickers briefly when the engine looses power and cuts out. But the ecm is capable of storing codes, so its an intermitent problem.

I am just running tuner cats and pocket programmer from my programs menu. I don't think anything else is running but I will check. I did use the stock prom as well as a prom burned by a """ tuner""" which have worked for many miles in the past. This is a good thought about the internet and making sure nothing else is running when programming. I will keep that in mind.

Grumpy, the "break out box" is a hell of an idea. I am going to look for one today. That would be an indespensible trouble shooting tool to have. Does anyone have a source for one of these??

If it were not for the guys on this site, I would have given up long ago on this project. In fact, I would not even have had the knowledge to even attempt it................bob



Thanks again. I will get off

 

You might want to check your spark plug wires too. Sparks jumping around can really freak out your ECM and stumbling under accellaration is a classic symptom of bad wires.

 

Also check your battery connections. I replaced my battery recently and thought I tightened everything pretty snug. Last night I was at a light and the car just died, but restarted fine. I pulled into an empty parking lot and poked around under the hood (it was raining lightly at the time), looking for ignition arching or anything like that. Then on a whim, I decided to check my battery connections. I jiggled the ground, and it was tight. Then I jiggled the positive connection. It was tight if I moved it in the direction you'd tighten the bolt (side terminals), but if I grabbed the cables and moved them toward and away from the battery, it was loose, and the engine almost died when I did it. I tightened it and it's fine now.

So check your battery connections!