Drive home last night was fine...coolant stayed about 200 - 210 with rad fans on....no problem. Swapped battery out last night, just to see if there is any difference....have to see what happens on way home tonight.

Anymore thoughts??????

 

I have the same situation on a 94. It cuts out only on higher rpm and extended high temp. It showed up on road race type event after several laps. I think it is the optispark so I will buy it and try it. Died on the track so my intermitent problem turned into no spark.

 

Last time I drove it, air temp was about 90F. Engine coolant temp came up to 225 with no problems...shut it off for about an hour. Got in, started it up...did not idle well....like it was vapor locked...blimped the throttle and all was fine, coolant temp at 205. Headed towards home and engine begins to cut-out. Hit the AUTO temp button with temp at full hot (90)...engine cut-out at various times. Coolant temp got into the 220s several times due to traffic, engine cutting-out...but never stalled. Finally got open road....able to turn AUTO off, coolant temp at 198F....engine cuts-out hard twice...thought it was going to stall....headed for roadside...but it kept going so I got it home. Sitting in driveway idleing....it went up to 230 and back down couple of times....engine would cut-out...but would not stall.

No check engine lite, but pulled codes to find once again: H16, H42. According to FSM, replace ECM. Did that twice...on third one. Got to be something else????????????????????

Brought O'scope home from work, will monitor pulses between ECM and OptiSpark tomorrow and see what drops out first....ECM reference to OptiSpark, or resolution pulses from OptiSpark to ECM.

Can no longer drive car now cause its going to leave me on the side of the road.

I'm thinking of having a FIRE sale soon!!!

 

my 93 Lt1 has been doing this...all winter long here in Portland it runs great, but when summer hits and the oil temp gets up ~200F, it cuts out during acceleration. today it was really bad...i havent replaced anything yet. not sure if i should try replacing things myself, or just drop it off at a shop...money is tight tho.

 

You've replaced parts, but you haven't checked the wiring. I would very carefully check the various pins and connectors for signs of corrosion and/or damage. Specifically I would look at the harness that runs from the Opti up to the connector on the intake. I would also check the pins/connectors at the ECM. From there I would look at the wiring associated with the ICM and the coil.

 

I think this car was fixed a month or so ago:

http://forums.corvetteforum.com/c4-t...95-solved.html

 

YEP....car all fixed now. It was the ECM. In fact just yesterday I re-installed the old ECM and drove it to work. Got to work with no problems. Air temp hit 103 for drive home.....thought I was going to make it home...but nope. Problem returned. Had my replacement ECM with me, swapped them out....drove home.

Quick history: did check all pins on ECM connector. Checked wiring harness. Replaced OptiSpark harness.

 

thanks for the details and update!!

 

Aim a hairdryer at the PCM with it cold.

 

i just put a cardone rebuilt ecm in it, problem still there. maybe that esc/knock sensor thing?

 

Yes, wires can get heat soaked too!!

 

I would try to isolate it to either a fuel problem or a spark problem. It could even be an electical short that only occurrs when the car is hot and drops sytem or sensor voltage to an unacceptable or irractic level, even messing with the injector signals. If you could monitor some of the components/inputs to the ECM/PCM then you might find the erratic component. Of course this is a closed loop system and you may need to run it in open loop/limp mode to eliminate feedback issues (If possible).

I had a new pickup truck and when it was hot outside at my work it would crank but not start. The dealership could not find anything wrong because by the time they checked it the next morning it had cooled down. After twice with this problem the kid had the idea for the dealership to run the truck with the heater on simulating the hot cabin temp and low and behold the dealership finally found the problem; a short in the wiring of the ECM/PCM under the dash behind the radio that only showed up under hot heat-soaked condtions of the cab.

 

I like Carpenters approach on a post in the C4 Tech for a heat related problem. Get a can of Freeze-it Spray from Radio Shack and try spraying some of the heat soaked components under the hood and see if the problem goes away.