My 1996 LT1 (automatic, 67K) has been hesitating upon startup but eventually recovers. Following a long period of driving (>1 hour), it sometimes stalls but usually starts right back up. Yesterday, however, it started then stalled 5 seconds later not to start again. I had to be towed home. I originally thought it was the optispark as the symptoms were the same as what I experienced last time the optispark had to be replaced. That is, a couple of hesitations here and there, then no spark to the engine but with fuel pressure. The dealership does not believe that it is the optispark, rather, they believe that it may be the computer module as they are getting the codes B0054, P0118, and P1115. Only the first is indicative of a computer issue as far as I can tell. Their theory is that the computer is failing to read the key code (even though B0054 is not this specific error) and cutting the spark to the engine. Thus, it goes into anti-theft mode. Obviously, replacing the computer is time consuming and money consuming so I thought that I would reach out here to see if someone can confirm or deny that computer replacement is the best course of action. What do you guys think?

 

I am not there but your description of their opinion seems to make me wonder if they know what their talking about. The anti-theft mode or better known as VATS basically works with initial key insertion. It checks the pellet resistor in the key. But once the engine is running it will not shut down the engine, it will only prevent it from starting if the key is wrong. This is controlled by the CCM computer which runs anti-theft and the basic car systems. The computer that runs the engine is the PCM computer and it provides the spark timing and takes all the inputs from the engine sensors. It also runs the fuel injectors. I assume the codes were for the PCM,? I don’t know, is that what they meant. Doesn’t sound like somebody has a good understanding of how the systems is configured and works. Sounds like their guessing, what have they measured?

For a start I would check would be the IAC (idle speed control motor). This can cause stalling and or poor running at slow speeds. Also the ICM might cause a ignition problem also. Fuel pressure check and hot coil wire arking to ground. Many other logical things can be checked to.

I think you post should be in C4 technical.