LT1 Optispark/timing issues

[WS6]

I can't remember if the LT1 cars had this switch but the L98 Corvettes did have an oil pressure switch hooked into the fuel pump relay. So if after a couple seconds there was no signal from the oil pressure the fuel pump relay would shut off.



Regardless, this makes me think of other tests. You'll need a test light and another person. You'll also need the pin outs for each connector. The Factory Service Manual has all this info. You really need to have an FSM and not a Haynes type manual to be doing this type stuff. In short, go through all the power leads on the PCM and make sure they are all on in the respective states. Meaning the ones that have battery power should be powered when the key isn't even in the ignition. The ignition ones come on when the key is turned on and stay on after the car is started. You may find one or two that turn off when you start the key but they should come back on while the car is in run and running. You'll also want to look and make sure none of them turn off after a few seconds once the car does start. Yes, it's tedious but I believe at this point it's an electrical problem. I'm also going on the basis that the car is shutting off like the key has been turned off and not dying like it's out of fuel.

You should also get an FSM because it will have a flow chart for diagnosing problems like this.

[barno68]

I got the answer from a member on LS1LT1.com:

"Is the PCM from a Corvette too? If so, they have an extra VATS switch that not everyone toggles, it's called Data Stream Fuel Enable. It will cause your exact symptoms, it lets the engine run for a few seconds and if it doesn't detect the VATS signal, it will kill the fuel injectors."

I reprogrammed the computer this morning by toggling off the Data Stream Fuel Enable switch and the engine runs just fine. I am very excited as the last time the car ran was 2004 (different engine of course)!

Now I just have to figure out why it will start with the remote starter and not the key... but that is for another posting.

Thanks to all that helped with this!