Optispark Internals.......

**BIG CAT** · 04-26-2013, 06:10 PM

hall effect would probably be the best. but the bigger hurdle is the size of the sensor. the tone wheel could be cut with a laser cutter.

**Injuneer** · 04-27-2013, 11:08 PM

You really don't need much to analyze the output signal. The hig res is a 0-5V square wave consisting of 360 pulses per cam revolution. That's 180 pulses per crank revolution, so by counting the events in one crank revolution (180 "0" readings, 180 5V readings = 360 events) the PCM knows the position of the crank within one degree of rotation. It uses the low res pulses to identify which cylinder is approaching TDC. There are 8 slots (one for each cylinder) and the length of the slots varies for 4 of the cylinders, alternating with short, fixed length slots for the other four cylinder. Again, the signal is a 0-5V square wave with variable length pulses. I can give you the exact output signal pattern if you want it.

I've also seen a post on another forum, from a guy in Russia who claims there are people there who are repairing the optical module, since they can't find new ones. I'm sending my old Opti to GaryRob, the guy who has developed the free OBD-II scanning software, and now free OBD-I scanning software that will read the PCM, the EBCM and the airbag control. He's an electrical engineer from Georgia Tech, and the stuff he does is amazing. He wants to dig into the Opti to see what he can learn.

After running with a vented Opti conversion for 13 years, and using only the optical cam position signal in the Opti, it seems to me that if you get the high voltage function out of the Opti, all the problems go away. The rust comes from the ozone generated by the high voltage discharge, so that's eliminated. Breakdown of the dielectric resin that covers the wires that route the cap buttons to the correct plug wire towers is no longer a problem. Getting it wet is not a problem. I'd say the oil leakage into back of the Opti would be the last remaining problem. Note however that my car is very low mileage, so it's not like the system has proven to be fault free for 100,000 miles.

What I had suggested a long time ago was to take the distributor stub with signal generator that MSD uses for their CPC system, and build an interface box that converted the stub output signal to the Opti pulse pattern.

http://apps.msdignition.com/ignition_27_7600.htm

**Tony Shepherd** · 05-01-2013, 12:36 PM

Originally Posted by Injuneer

You really don't need much to analyze the output signal. The hig res is a 0-5V square wave consisting of 360 pulses per cam revolution. That's 180 pulses per crank revolution, so by counting the events in one crank revolution (180 "0" readings, 180 5V readings = 360 events) the PCM knows the position of the crank within one degree of rotation. It uses the low res pulses to identify which cylinder is approaching TDC. There are 8 slots (one for each cylinder) and the length of the slots varies for 4 of the cylinders, alternating with short, fixed length slots for the other four cylinder. Again, the signal is a 0-5V square wave with variable length pulses. I can give you the exact output signal pattern if you want it.

I've also seen a post on another forum, from a guy in Russia who claims there are people there who are repairing the optical module, since they can't find new ones. I'm sending my old Opti to GaryRob, the guy who has developed the free OBD-II scanning software, and now free OBD-I scanning software that will read the PCM, the EBCM and the airbag control. He's an electrical engineer from Georgia Tech, and the stuff he does is amazing. He wants to dig into the Opti to see what he can learn.

After running with a vented Opti conversion for 13 years, and using only the optical cam position signal in the Opti, it seems to me that if you get the high voltage function out of the Opti, all the problems go away. The rust comes from the ozone generated by the high voltage discharge, so that's eliminated. Breakdown of the dielectric resin that covers the wires that route the cap buttons to the correct plug wire towers is no longer a problem. Getting it wet is not a problem. I'd say the oil leakage into back of the Opti would be the last remaining problem. Note however that my car is very low mileage, so it's not like the system has proven to be fault free for 100,000 miles.

What I had suggested a long time ago was to take the distributor stub with signal generator that MSD uses for their CPC system, and build an interface box that converted the stub output signal to the Opti pulse pattern.

http://apps.msdignition.com/ignition_27_7600.htm

Good to see you on the site Fred!