I put a lt1 in my 89 and it starts and runs fine until the temp gets to 190 and the car shuts down. The only code that I can pull is 18 which is off so why will it come on? When this started I hade the icm checked and it was fine so I changed the opti and same thing happened so I do not know where to look I used a 94 caprice pcm with a 95 camaro auto harness and I flashed it with a 95 camaro manual I do not know where to look so anything will be helpful. Thanks.

 

DTC 18 is telling you there is a fault in one (or more) of the injector circuits. What do you mean by "The only code that I can pull is 18 which is off so why will it come on?".

 

When using free scan it shows up as not used and when I looked in at the switch in c.a.t.s. it is off

 

Might be worth checking the injectors. Do you have 12V at the pink wire on each injector harness connector? Are all the injectors in the range of 12-16 ohms resistance? Do you have a 'noid light to verify the PCM is supplying a ground to fire the injectors? Check it with the engine cold, and then with the engine at max temp.

 

All the injectors are at 13.1 ohms and injectors plus fine. The car will stay running as long as it is above 1500 rpm after it starts to die the if you go blow that it will not start up unit it is cold. when I got the engine the guy pulled the pcm out of a puddle of water in the car is there a way to test the pcm or dose that not sound like the problem

 

Any electrical component, including the PCM can suffer from overheating. The injector drivers could be breaking down

 

check your ignition grounds.

 

I checked all the grounds and even ran new but still getting code 18. I took the pcm off my 95 still same thing as soon as I start it the code pops up, where can I look? will a data log help you any? thanks tyler

 

If you checked the resistance of all the injectors, as you indicated, and if you verified with a 'noid light that all the injectors are pulsing, its hard to understand why the code would set. But the fact that two PCM's set the same code would appear to confirm there is an electrical problem with at least one of the injectors. The code sets when the voltage on one or more of the individual injector circuits is "near 0 Volt".

Did you check the operation of the injectors under both cold and hot conditions? Might be heat causing one of the injectors to break down. Test them when the engine is at max temp, if you didn't already.

 

I pulled all the spark plugs and found the cylinder that was lean and replaced the connector and that seamed to fix it I do not know why the noid light did not work on that but I got it not the road and that is all that maters thanks for the help