Opti-sensor?
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Joined: Jul 2003
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From: Las vegas, NV
Opti-sensor?
I have owned my car for a little over a month now and i am still lurning everything about it.. I have seen alot of people talk about Opti-sensors (everyone seems to hate them) so i was just wondering what they are, what they do and how much they are if something goes wrong with mine?
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Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
The OptiSpark is more than a "sensor". It is the distributor. Sends the spark to the correct plug. It functions just like the distributor that all earlier small-block Chevy motors had on the top-rear of the intake manifold. But on the LT1, its mounted on the front of the block, and driven off the nose of the cam.
The Opti has two distinct portions.... the front half is the high voltage setion, consisting of a cap and rotor, with 8 plug wires and a coil wire attached. The back half contains an "optical sensor" that feeds the computer information about the cam and (psuedo) crank postion. The computer uses an irregular pattern of 8 pulses per cam revolution (low resolution signal) to determine when to fire the sequential fuel injectors. It uses a 360 pulse per cam revolution (high res) siganl to fine tune spark timing. If the PCM can not find the low resolution signal, it shuts down the fuel pump and injectors and the engine will not run.
While the OptiSpark is an excellent technical solution for providing spark and injuector timing, it seems GM made it out of cheap compenents, and located it in the wrong place. Since it is right under the water pump weep holes, it gets wet when the water pump dies. Or if you hose down your engine, if you hit a real deep puddle, etc. The liquid leaks into the case, primarily through the harness connector, or possibly through the case seals, and destroys the internals.
The 93-94 Optis are identical. In 95 GM added a vent system to try and remove ozone from the case and minimize corrosion. Unfortunately, you can't use the "vented" Opti on a 93-94 unless you change the timing cover, timing set and cam.
A faulty Opti can cause a stumble as the car comes off idle, surging up to 2,000rpm, and intermittent misses from maybe 4,000rpm to redline.
Some people manage to go through Opties in a few thousand miles, but yesterday I saw a post from someone who had over 200,000 miles on the original.
Hope this helps.
The Opti has two distinct portions.... the front half is the high voltage setion, consisting of a cap and rotor, with 8 plug wires and a coil wire attached. The back half contains an "optical sensor" that feeds the computer information about the cam and (psuedo) crank postion. The computer uses an irregular pattern of 8 pulses per cam revolution (low resolution signal) to determine when to fire the sequential fuel injectors. It uses a 360 pulse per cam revolution (high res) siganl to fine tune spark timing. If the PCM can not find the low resolution signal, it shuts down the fuel pump and injectors and the engine will not run.
While the OptiSpark is an excellent technical solution for providing spark and injuector timing, it seems GM made it out of cheap compenents, and located it in the wrong place. Since it is right under the water pump weep holes, it gets wet when the water pump dies. Or if you hose down your engine, if you hit a real deep puddle, etc. The liquid leaks into the case, primarily through the harness connector, or possibly through the case seals, and destroys the internals.
The 93-94 Optis are identical. In 95 GM added a vent system to try and remove ozone from the case and minimize corrosion. Unfortunately, you can't use the "vented" Opti on a 93-94 unless you change the timing cover, timing set and cam.
A faulty Opti can cause a stumble as the car comes off idle, surging up to 2,000rpm, and intermittent misses from maybe 4,000rpm to redline.
Some people manage to go through Opties in a few thousand miles, but yesterday I saw a post from someone who had over 200,000 miles on the original.
Hope this helps.
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