81 ecm prob?

[TAZ 76]

Hey there I'm new here, and new to diag. probs on my vette. The story goes, got car road worthy and drove for 2 weeks. On the last drive, after I got back in , the batt was dead. I have batt leads to the back of the car (because of shaved handles). + goes to the pos batt, - goes to the bracket that holds the ecm behind the batt. My friend hooked his end (jump vehicle) up backwards, only for a quick spark. Then hooked up correctly. after letting batt take a charge, went to start and would fire but not run. If you give some throttle it will miss, backfire ect. Towed home. Now if I disconnect the 4 wire harness that goes from the dist to the car, it will run and sounds close to norm. My question is do I need a new ecm? If so does anyone have a used one f/s. Or could it be something else. Big thanks for any help Aaron

 

[Tritium007]

Not sure of exactly what the effect may have been on the ECM in your configuration under those circumstances, but if you diconnect the battery for about 10-15 minutes, the ECM should reset and clear any bad inputs. Typically, when you changeout a bad sensor or correct the cause of any bad inputs, such as the O2 sensor, the ECM will eventually correct its output, but disconnecting the battery leads will reset it and it takes less time for the corrected inputs to have any effect. This may not solve your specific problem, but it would be worth a shot to try. It's free and it's easy. You might also want to post in the L81 vette registry section as it is specific to the 81's.

Mike

 

[TAZ 76]

Thanks Mike, I'll give it a try tom after work. Let you know if it works.
Aaron

 

[TAZ 76]

Well resetting the ecu made no change. Any thing else I can try to troubleshoot? (not shure if my bulb for check engine is good i'll check it tom after work.)
Thanks, Aaron

 

[jdp6000]

Well resetting the ecu made no change. Any thing else I can try to troubleshoot? (not shure if my bulb for check engine is good i'll check it tom after work.)
Thanks, Aaron

I don't think hooking up the battery cables wrong would fry your ecm. There should be an inline fuse to the ECM...have you checked it? I have an 82 so its a bit different. Is your fuel pump in the tank??

Jim

 

[Peer81]

On 81 the fuel pump is at the block

Groeten Peter.

 

[TAZ 76]

Checked fuse, not bad. Wouldn't grounding to the case draw current through the board, and not be passing through the fused circut? (I didn't think of things this at the time that I was wiring.)

 

[TAZ 76]

Thanks for the help everyone!!! Went to napa online and found a reman ecm. Took the part # in and had it overnight, only $91.50. They didn't even ask for a core or tack on a core charge. Put it in late last night and took for a spin tonite, works as good as new!!!!! Will try to get some pics of the show tomorrow.
Thanks again, Aaron