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LT1 Optispark CODE 36

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Old Aug 24, 2025 | 07:11 PM
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Default LT1 Optispark CODE 36
As the title states, my 1992 LT1 recently started throwing a code 36. From my research it seems to be the High Res Opti fault, which could explain why it dies at idle after two minutes and then has a rough start. Was wondering if anyone had something similar before I replace it. I've already checked over all the wiring, has a MSD coil, and swapped the ICM with a known good GM spare.
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Old Aug 24, 2025 | 10:45 PM
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That's a pretty good set of data points that you're gonna spend an afternoon replacing the opti.
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Old Aug 25, 2025 | 06:58 AM
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Yep, that code tells you that the optical sensor inside the distributor is failing. Time for a Petris.
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Old Aug 25, 2025 | 08:34 AM
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If your opti is original to the car do not throw it away. Dan
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Old Aug 25, 2025 | 09:34 AM
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My current opti is from O'Reilly's and it's been great. Lifetime warranty too.
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Old Aug 25, 2025 | 08:53 PM
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Originally Posted by MatthewMiller
Yep, that code tells you that the optical sensor inside the distributor is failing. Time for a Petris.
Petris was my first choice but looks like none will be in stock or made till end of of September. I have plenty of parts cars and spare parts around, turns out one of them has an MSD Opti that was running with no issues. I've cleaned it up and I'll swap it in for now.
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Old Aug 25, 2025 | 09:50 PM
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Originally Posted by Snaps
Petris was my first choice but looks like none will be in stock or made till end of of September. I have plenty of parts cars and spare parts around, turns out one of them has an MSD Opti that was running with no issues. I've cleaned it up and I'll swap it in for now.
The MSD opti wasn't well regarded, but hey if it works go for it. As I recall, that's the one that let you do a manual timing advance somehow?
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Old Aug 26, 2025 | 08:10 PM
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Pulled my Opti today, anyone ever seen this goop covering it?

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Chinese boogers.....
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Old Sep 1, 2025 | 10:27 PM
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May have found my Opit issue
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Old Sep 4, 2025 | 07:41 AM
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Sorry for the late reply. Yeah, looks like you have a leaking seal behind the Opti. There are videos on YouTube for how to replace that. As I recall, there's a little tapered tool to help with it.
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Old Sep 4, 2025 | 08:30 AM
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Originally Posted by MatthewMiller
Sorry for the late reply. Yeah, looks like you have a leaking seal behind the Opti. There are videos on YouTube for how to replace that. As I recall, there's a little tapered tool to help with it.
You need the tool if the leak is at the water pump drive seal. You do not need a tool if the leak is at the opti seal. Dan
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