84 Chevy C10 P/U with 95 LT1 4L60E.

Occasionaly the engine will die suddenly while driving or parked, but will start right back up with no hesitation. May run for 30 minutes or 30 seconds before dieing. It's as though you turned the ignition off.

It's not losing fuel pressure, computer is not losing power or ground (was able to make a recording with Data Master Dyno), tried wiggling wires (didn't reproduce problem), tried another MAP sensor, ignition coil module, PCM, opti, was replaced approx 6 months ago. I can't seem to find anything on Data Master that would trigger the PCM to kill the motor. PLEASE HELP. I can email the Data Master file if anyone would like to take a look at it.

Sam

 

Do you have an ocassional miss? I'm not sure if it is related to this. My car had a broken valve spring. The last 2 times I drove my car before I pulled the motor, the car would just die if I were driving and let it idle. I had to rev it to keep it from stalling.

Z

 

No miss, sputtering or any other signs prior to stalling. Runs perfrect until the point it dies.

 

Does your oil pressure drop and then return when you give it gas?

 

I haven't noticed any abnormal drops in pressure. Next I'm get a chance to drive it I'll keep an eye on it. I'm trying to locate an osciliscope to monitor the opti's signal to the PCM at the point it dies.

 

Try a voltmeter set to AC.

 

I messed with it some today. I noticed the fuel pump turns off just as it dies but comes right back on after the engine is dead. It appears the injectors are not being pulsed either, but I was only monitoring one injector so it could have been from the decrease in rpm. It has to be loosing spark to all cylinders and/or injector pulse, since the engine dies instantly. One of the times it almost died but corrected itself fast enough to start running again. I also noticed the SES light does not come on after it dies. Only after turning the key off then back on does it come on.

It doesn't seem to be oil pressure. I observed no drops in pressure and I actually unplugged the pressure switch for a while.

After looking at the data master file. 13 seconds before the engine dies both O2s flat line at less than 20 mv. 3.5 seconds after that it shows injector fault and stops short term counts but remains in closed loop. About 20 seconds later, rpm starts to drop (starting to die), injector base PW-MAP-IAC pos and DRPms (? not sure what this is) all start to rise.

From this it seems the PCM is not killing the engine (increases inj PW) but what is stopping the fuel pump? It is still receiving steady voltage according to the recording. If it were the opti, wouldn't PW drop to 0? What is DRP ms? Why would both O2s flat line lean and the PCM still remain in closed loop? Has anyone ever had a program go bad? When I switched PCMs I copied the program from one PCM to the other.

WTF

Please help!