Does the 95 lt1 computer read a signal off of the Cam angle sensor (do we have one?), or off of the crank angle sensor? Will it fire with only one?
What kind of signal do they put out, and is there anyway to replicate that signal?

 

The optical sensor in the Optispark distributor tells the PCM the cam position. The wheel on the optical sensor has 8 slots, each representing one cylinder. The alternating slots are variable width, to identify the specific cylinder. This allow the optical module to output a 5V square wave the identifies each cylinder by the length of the pulse. This is called the low resolution pulse pattern.

To increase accuracy of ignition timing, there is a second set of 360 slots on the optical wheel, that in effect produces 360 uniform width pulses per 4-stroke cycle, allowing the PCM to calculate the position of the cam with extreme accuracy, resulting in extremely low spark scatter, increaing fuel economy and allowing aggressive timing advance. This is called the high resolution pulse.

So far no one has been able to replicate the signal. The solution many of us have chosen is to use the optical sensor for its extreme accuracy, feeding aftermarket systems that take advantage of the cam position signal, to drive 8 independant coils. The Bailey LTCC is a device that runs 8 LS1 coils using the stock PCM and Opti. There are aftermarket ECU's that will accept the Opti cam reference data and drive a variety of ignition systems. I run the Opti cam data to a MoTeC M48Pro, which, along with their IEX 8-channel ignition driver, allows running 8 LS1-style coils in direct fire.

I have suggested several times that the logical way to replicate the Opti pulse signals would be to look for (or develop) an interface/translater that would allow the MSD CPC cam position stub to feed the stock PCM, rather than using the Opti. So far, no one has pursued that concept.

 

I'm building a bench set up for my class and am looking at a way of simulating a crank/cam signal to the computer in order to fire the injectors. i was thinking of using a square sine wave generator for the crank, but after looking at it closer i see that this would be very difficult because of the different size teeth on the crank hub. Any ideas/comments?