G.M. Tecs only please!!!!?

Question

I have a 1991 Caprice with a 5.0 engine and I got a problem that is driveing me nuts!. The car starts great even in cold weather and idols smooth but once the engine warms up to operating temp. and I come to a stop and put load on the engine the ignition cuts out and back in randomly. also when driveing and trying to acelerate for a hill the same thing happens. the car doesnt miss a beat when its in closed operation at all. so far to fix the problem I have replaced the ignition swich, ignition module (4 times) , the coil, rotor,cap,I have even replaced the whole distributer and the P.C.M. main computer along with all ignition wireing and plugs.There are no trouble codes showing up at all. and yet the problem persists! I unpluged a sensor yesterday after the car was warmed up and the miss disapeard and everything ran great (CLOSED LOOP AGAN) . I double checked all grounding wires and they check out good. Yesterday, I wonder if the Eltronic spark control module could cause this???

I wonder if anyone out there knows what the E.S.C. module does? I think it might control the timing and spark from the distributer and maby the emissions

I think because the car runs great in closed loop that there are no loose wires orr there would be a ignition problem at all times not just in closed loop

I dont think its the thermastat as the engine temp is stable at the recomended operating temp the car is not overheating.

I have unplugged almost all of the sensors one at a time puting the computer into close operation and the car runs great in its closed operation. when I again plug the sensors in the miss starts once agan. I have checked all of the sensors idiviguly and they all check out good

The car has no aftermarket parts instaled and it has only 63000 miles on it

All fuses check out good no broken circuts in any wireing.

Answer 1

Would like know to which sensor you unplugged to make it run better. Also, access to a scan tool would be very helpful, not to read codes, but to monitor the data stream. If the data stream cuts out at the same time the problem appears, then the computer is losing power, if not, most scanners can take a snapshot of every sensor at that moment. Also, given the age of this car, how much aftermarket electric equipment has been installed and or removed? Old cell phone? Hopefully nobody tapped into an ign supply circuit in the fuse box with a brass fuse-tap. They destroy the terminals every time and are usually the last hing anyone suspects. Take the fuses out and feel how tight the fit is, don't just look to see if they are blown or not.

Answer 2

I have the same car yr and motor, mine did the same thing,and yes i did what you did , but it fixed the problem, but i can not figure out what caused it in the first place, the only other thing i did was take the line off the egr valve and pluged it off,good luck.

Answer 3

Thermostat