I have a 95 z28, pretty much stock except cold air intake and cat back exhaust. It is an auto with about 150k on it. The car never has been a real powerhouse. It is a convertible, and I had a new top put on it over the winter. Since I have gotten it back it has an intermediate shut off of the lt1. It doesn't matter if its been running for 2 hours or 1 minute, it will just shut off randomly. I don't lose any power from the battery, after it shuts off it sounds like its not getting any gas. Usually it will refire after about 10 minutes, but before it refires the air pump makes a spinning noise. If the air pump doesn't make that noise it won't start again. I have replaced the fuel pump, fuel relay, tps, coil, cleaned the maf and have taken it to many garages including the local chevy dealer and no one knows what is wrong with it. It doesn't show any codes on the dash and I was told that it wasn't throwing any codes on the garages computers either. I was told by some people that it might be a crank positioning sensor, which I think is on the opti. I replaced the opti and water pump last year. This has to be the biggest POS that I have ever owned. I have also replaced the O2 sensors and the coolant sensor. The other thing that I thought of was the vats system, but the security light doesn't come on when it quits. I also replaced the icm with no difference. HELP!!!!!!!

 

Has anyone checked the fuel pressure? Sounds like it could be a fuel pump/fuel pump relay problem.

There are codes that shut the engine down, that do not turn on the SES light. That's why its important to do a scan yourself, if possible. There is free software available for scanning, and all you need is a cable.

I am also seeing numerous problems with the ignition switches on these cars lately - burned terminals, faulty switches, etc., resulting in engine shutdowns. The AIR pump runs for a couple of minutes at cold startup. If the pump isn't getting power (ignition switch problem) it would certainly coincide with a "no start".

There is no crank position sensor on the OBD-I LT1's. The ignition and injection are timed off the cam position sensor, which is the optical module in the Opti. Interestingly, if you lose the low resolution pulse, it sets DTC 16 (which does NOT turn on the SES light). and shuts down the fuel system.

 

What kind of cable do you need and would you just hook it to a laptop with downloaded software on it? I was thinking about replacing the opti again, just getting tired of spending money on it. I first thought about the fuel system and checked to make sure that the pump ground was good. It all checked out ok. I think the pressure was around 47, not sure its been a while since I had it checked out.

 

Look in the computer/diagnostics/tuning section for a sticky about software and what you need.

 

Thanks

 

I think that I found out what my problem was. I have cleaned the ignition and the key with alcohol and so far so good, not dying of late. Hope that solves the problem.

 

Once the engine starts, it will not shut down due to a problem with reading the key pellet. That would be an extremely dangerous strategy. The key is important for engaging the starter and allowing the fuel system to activate to start the engine. That's all. If it's a problem at startup, the "SECURITY" light would be flashing.

If a component of the PASS-key system fails when the car is being driven, the"SECURITY" light goes on solid and the security system is bypassed.

 

I fixed the problem, bad opti, replaced and now doesn't shut off.
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cant you flash code 95s???

 

Negative. Last year you could do that was 1993.