Ok, just looking to get a little head start on a problem i had with my 95 Z tonight....I drove the car from cold about 7 miles home, and within a block of my house, the car just up and dies out of nowhere, and will not restart. I was rolling when it died, i downshifted to 3rd; got a backfire and that was it. No symptoms leading up to this problem whatsoever. The car is in a good state of tune as far as air filter, plugs and wires, and was running trouble free since i have owned it. I don't know the history of the opti and cap/rotor, but the car does have 139k on the clock. Before starting a new post, i did do a little searching as well. So, i just went back out to the car (it has been about an hour) to listen for a fuel pump, but it is pouring outside and the previous owner, to make matters worse, wired the primary fan to come on with the key, so it was hard to hear. Well, what the hell i say....i crank it and it fires right up and runs fine. I shut it right back off. So, if it is not the FP (I know it still can be) are the odds pointing towards the Opti? I didn't even have a service light, so i am assuming it didn't store any codes....As a side-note, i had a friend inspect the car for me a few weeks back, and he said he thought he heard a very slight miss up high when the car was on the dyno, although i never really noticed it before or after that. (He did say slight...) Ironically enough, on the ride home tonight, i thought to myself "this thing is running great tonight..." Anyway, it is raining, i am completely tool-less, and have no scanner. Does this incident sound familiar to anyone? Thanks in advance for your insight!
Jack
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It could also be the ICM sometimes when they get older they heat up and can cause the engine to die. Once they cool off you can restart the car and drive it until it gets hot again. Thats why a lot of guys mount it so its not touching the head like it was originally mounted stock. Just another suggestion to look at.

 

I would try a new fuel filter. I a similar expereience on another car that drove me nuts for a week - a brand new fuel filter was plugged with crap. The car would run for a few minutes after sitting (or allowing the fuel pump to build pressure) for 20 minutes or so.
If it was the opti, you would get a code of some sort.

 

I have a 94 Z28 and I would drive it for ten minutes and it would shut it self off. If you let it sit for about ten minutes it would restart and do the same thing ten minutes later. I did the following:
1) Checked fuel pressure while driving (guage on the window) good, 40PSI, same problem 10 minutes later.
2) Changed the fuel filter, Coil, and the ICM...same problem 10 minutes later.
3) Back to the forum...decided to change the ignition switch. Pulled out the entire steering colum (thanks Shoebox for the great pictures), changed the switch...same problem 10 minutes later.
4) Replaced the OPTI, replaced the waterpump as long as it was off, replaced all the hoses...and went with the OTVC wires as well. PROBLEM SOLVED!!! The OPTI had on 44K on it, but it can cause a host of problems. I also found two wires that were slightly damaged. The OTVC wires solved any issues with touching the headers and I highly recommend them. Those other items can give you problems....but eventually you will be replacing the OPTI.
Hope my saga helps.....I read many messages on this board and it was a fantastic resource. Most guys I contacted said to change the OPTI...they were right.
P.S. I did not have any SEC light as well. I have purchased a OBDI cable and software to T-Shoot in the future. Live and Learn.

 

Don't forget to change/look at the pigtail that goes into the opti. $40.00 is a small price for preventive maintenance. sounds like the same thing that happened to me. Six months and two Opti's later the problem seems fixed for now. (My pigtail was corroded from hell) I replaced it the with the second opti.

Bill Mitchell
95 Z28
58,000 miles.

 

Guys, thanks for all the useful info! Wolffman, your post sounds exactly like what is happening, right to the letter. This morning i drove the car 7-10 miles to work, completely trouble free. On the trip home tonight, the exact same problem occurred again, at practically the exact same spot! It stumbled badly, then died. I tried to restart it a few seconds later, and it stumbled a little bit, but would not start. After attempting to start, i heard a slight "afterburn" in the exhaust....(I can't believe i have been lucky enough to roll right into the driveway both times!) I suspect it will run fine again in the A.M. Tomorrow and over the weekend i will try to kill this problem off...It definitely seems heat related. I will post anything else eventful...

 

Well, a little more knowledgeable input for today....I got the car to a friends driveway and let it udle until it stumbled, and died. I immediately checked for spark at the coil and injector pulse, had neither. Then a few minutes later, i tried it again, and it started. Ran for about 15 seconds and then the injector pulse became erratic, it stared running like crap (obviously) and died. Once again, no injector pulse, no action on the spark tester. I'm going to go pin out the opti harness just to make sure, but now i am really leaning towards the opti, i'll have one in the A.M. I'll definitely post results for others to benefit from...
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Well all, after a few days of "making sure" it seems it was definitely the opti...Changed it out with a New AC Delco unit with an MSD cap and rotor, did the ICM relocate "mod"....all seems to be 100%. Thanks for your help!

 

I know I am too late to the thread, but be aware that DTC 16 (which indicates lack of low resolutiion pulse from the opti) does NOT cause the SES to come on. So, you MUST check with a scanner to see if it has occurred. The engine will not run when the code is active, but in a case where the engine runs again later, the code can be retrieved from history. Just FYI for anyone that might read this thread later.