Hi, I posted the following on the DFI/ECM thread last week, and no one responded. I'm hoping someone here can help. Please!

Hope someone can help me. I have a '87 MAF on a 383 I built and have it in a '41 Chevy coupe.Just about done with this project after 2 years of doing a frame off. Her's my problem(s). With the timing bypass wire disconnected, car will start and run. Timing set to 6*. When I connect the bypass wire, car won't start. Timing stays at 6* while cranking, so it's not being retarded by the ECM. It wants to start, and does momentarily, but as soon as you let go of the key it quits. There is no solenoid or resistor in the system.(like the old ones that wouldn't start if you had a bad resistor)
Anyone have any ideas? I seem to remember seeing something like this on this thread a while ago, but can't find it now. Would really like to get this finished and on the road this summer. Would a bad or wrong CTS cause this?

 

As it runs without computer control of the advance ( wire disconnected ) I would suspect the ESC ( electronic spark control ) module first
Have you got the ALDL connector hooked up so you can pull codes?

 

Thanks for the reply. Yes, ALDL is hooked up. Have not gotten any codes. Will look into checking the ESC. Do you know a procedure for checking it?

 

if you start the car with the wire disconnected,then plug it back in while its running...will the car die? it should set a code then if thats the case and lead you to the culprit. but it sounds like the esc ..especially if its a cheap replacement one that you put on during the swap.they tend to burnout rather quick.

 

86White. Thanks. No, I have not plugged the bypass wire back in while running. I was a little apprehensive about doing that for fear of-the unknown? Is it OK to do that? The ESC is the original GM one,not a replacement. Not that it can't be bad. I'n looking for a procedure to check it tonight.

 

yes you can plug the bypass wire in while running.this is how the ecm takes back over control of the spark timing.

you should have a code for the "est" when you do thise and it goes away after you turn the car off then on again.if the car runs and idles with the wire disconnected only..then something is telling the ecm not to advcance the timing and it has no clue what the base timing is...hence it stalling and hard to start.

my 383 likes base timing bewteen 10-12* i find.the ignition module sounds like the culprit here..but it should give you a code.