opti-spark?
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Instructor
Joined: Aug 2025
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From: north central Iowa
opti-spark?
I less than a week ago bought a 1994 corvette with just 25,000 miles. It's a very nice car, but the engine wasn't as clean as I like, so as carefully as I could, a voiding the front of the engine, I washed the engine using purple power, and a garden hose with a spray nozzle. I was aware 1994 Opti-spark was moisture problematic. When I was finished cleaning, my car started right up and ran fine for 15 minutes, and then I shut it off. About half an hour later, I wanted to start the car, and it won't start. I now have it pushed into my garage, blowing fan air at the engine these past three days, and still it turns over fine, but refuses to start? Does this sound like an opti-spark issue, or is there an accessible coil that could be wet, and I could dry off, or anything else to consider. I'm in north central Iowa, and am now thinking I may have to have my car hauled up to St. Pau lfor a quality opti-spark fix. I'm unaware of any closer shop that I can rely on. All help is gratefully appreciated.
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Instructor
Joined: Aug 2025
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From: north central Iowa
I read that the power steering reservoir has to be removed to access the coil. That's more than I'm comfortable with. Sure hope some people smarter than me will help me. Again, advice is appreciated. It's close to three hours from my home to the St. Paul corvette shop, and a tow there will be difficult to get, and expensive. If anyone knows a talented shop closer to me in north central Iowa, please let me know,
Melting Slicks
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2023 C4 of the Year Finalist - Unmodified
I just sent you a Private Message. I tried to send it yesterday, but I couldn't with you only having a 1 post-count. But today I can, so I did. Read the message, print it out, take it out to the car and follow the suggestions to pull the codes. Let's start there. If it turns out to be the opti, you want a Petris. I've seen recent reports on here that the pin-drive Petris have a delivery date in late September.
A 25,000 mile 94 opti shouldn't be giving trouble from age. When you washed the engine, was it stone cold, or had you run it to move around to get it in the wash area? If the latter, the opti may have condensation on the optics or shutter-wheel affecting operation. If it got wet, it should work again if it can be dried out. If you have opti codes, I have an idea to try to "dry it out". Read the PM. Get the codes.
EDIT/ADD:
^^ This is a classic scenario for condensation forming inside the distributor. ^^
It should be setting a code. Again, let's start there.
A 25,000 mile 94 opti shouldn't be giving trouble from age. When you washed the engine, was it stone cold, or had you run it to move around to get it in the wash area? If the latter, the opti may have condensation on the optics or shutter-wheel affecting operation. If it got wet, it should work again if it can be dried out. If you have opti codes, I have an idea to try to "dry it out". Read the PM. Get the codes.
EDIT/ADD:
When I was finished cleaning, my car started right up and ran fine for 15 minutes, and then I shut it off. About half an hour later, I wanted to start the car, and it won't start.
It should be setting a code. Again, let's start there.
Last edited by IHBD; Sep 9, 2025 at 12:53 PM.
Thread Starter
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From: north central Iowa
Ibhd
Sir, You were right....I sent you a PM, and received a message back that said "user could not be found". What I want you to know is that I'll do as you advise as son as I can. I'm not feeling very peppy today, and think I'll need a clear mind, energy, and patience to make this happen correctly. It sounds a little daunting at first glance, but I will get it done, and get with you on results. I am so very happy you are helping me. It's sure not taken for granted. Doug K.
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From: north central Iowa
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From: Cape Coral, Florida
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From: north central Iowa
It's been impossible for me to locate any shop with experience working on corvettes, electrical or otherwise. I'm about half way between Des Moines, and Minneapolis/St. Paul Almost all, is rural in between. There may be talented corvette specialists closer than St. Paul, but I'm aware of none. TY
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Verdad Gallardo
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From: Cape Coral, Florida
It's been impossible for me to locate any shop with experience working on corvettes, electrical or otherwise. I'm about half way between Des Moines, and Minneapolis/St. Paul Almost all, is rural in between. There may be talented corvette specialists closer than St. Paul, but I'm aware of none. TY
Corvettes don’t have some one of a kind ignition or electrical system…Opti was used on 5 or 6 other GM platforms…good luck !!
Instructor
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My suggestion if you know for sure you're in over your head, buy a petris optispark and either find a local C4 LT1 owner who can offer to do it or a good shop. Definitely keep the Optispark that came off the car. It might be a genuine GM/Mitsubishi opti that can be cleaned and either sold or kept as back up. If it's not, discard but check for sure. Good luck.
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From: north central Iowa
My suggestion if you know for sure you're in over your head, buy a petris optispark and either find a local C4 LT1 owner who can offer to do it or a good shop. Definitely keep the Optispark that came off the car. It might be a genuine GM/Mitsubishi opti that can be cleaned and either sold or kept as back up. If it's not, discard but check for sure. Good luck.
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From: north central Iowa
Ibhd
Dave...I went out early this morning to attempt the diagnostics. I had to squirm my best to view that plug, and with my crippling poor close-up sight, had trouble. I'm going to wait for my wife to get up, and have her take a picture, and then use a magnifying glass. But, I have big newes. As I have daily, I gave a quick try to start the car, and to my complete amazement, it started! Sounds like it's running decent, but I shut it off right away, not wanting to press my luck. I've had two electrical fans running since Saturday, pointing at where I think the opti-spark is...maybe that's helped? I'm a little scared to try to drive it, and am anxious to see what the diagnostics read. I need to jump the 4th cavities over from the left, starting from the side closest to the steering wheel and driver's door? I get a little confused when I'm contorted under there. Also, I tried to send you a PM, and may have been successful. Doug K.
Melting Slicks
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You may find it helpful to run the power seat all the way rearward, and tilt the steering wheel full-up to minimize contortions to get under the dash to access the connector.
That it started is really good news. I think you're going to be ok. I'd start it and let it run for at least 15-20 minutes, shut it off for a couple of hours to heat-soak, then attempt a restart.. If it restarts with no drama, you're probably out of the woods. If it doesn't we'll go with my idea to evacuate the distributor of moisture utilizing the factory opti ventilation system that is on the 94.
EDIT/ADD: I had a thought. When the engine runs, the distributor vent/evacuation system is in operation. So just running it should eventually evacuate any remaining moisture. So for the next few times you start it, let it run at least 15 minutes, even better drive it around the block close to the house until you regain confidence that it is ok again. Give the vent system time to do its job, which it can only do with the engine running. The more and longer it runs, the better.
Last edited by IHBD; Sep 10, 2025 at 10:45 AM.
Thread Starter
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From: north central Iowa
diagnostics jumper
I will start and let run or drive the car in 15-minute or so integrals as you suggest. I'll do it several times. Also, I've tried my best to jump those cavities, and just can't get it done. I'm thinking it may be easier if I had a solid core wire, which I need to go to town and get. If the car starts and runs well, might I still benefit from checking with that diagnostic plug? Thanks again, Doug K.
Melting Slicks
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From: So Cal
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Use a paperclip straightened and bent into a 'U'. It is data level voltage, you won't get shocked.
If you find an H16 in Module 4, you'll know for sure that the moisture event in the opti was most likely the cause of the no-start.
Same with an H41 in Module 4, which is something to do with the Ignition Control Module, although if it was 'water' in the ICM connections, it may not set an H41.
I like data. I like figuring out the root cause. Knowing what the problem was helps build confidence that the issue is resolved. But this is just the way I roll.
If you find an H16 in Module 4, you'll know for sure that the moisture event in the opti was most likely the cause of the no-start.
Same with an H41 in Module 4, which is something to do with the Ignition Control Module, although if it was 'water' in the ICM connections, it may not set an H41.
I like data. I like figuring out the root cause. Knowing what the problem was helps build confidence that the issue is resolved. But this is just the way I roll.
Team Owner
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You might find Delphi Metri-Pack 150 Series male terminals available locally to you or maybe even consider buying on-line and fabricating a couple jumpers. Delphi part #'s 12047581 or 12059894 might be available to you. They're very inexpensive. I believe that Mouser has no $$ limit on orders and $7.99 minimum for shipping. They're often the least expensive but there are certainly many others. Larger ACD Jobbers also often inventory these.
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Instructor
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From: north central Iowa
Diagnostic readings
Dave, I got the jumpers installed. When I turn the key to "run", in big letters and numbers, I first got H31 on top, with a small 1 or l an inch or so lower. Then the screen read H33, then H35, then H37, and after that a small 4. appeared, followed by a small 9., followed by an A., and then a 1.0......can you ascribe any meaning to this? TY, Doug
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From: north central Iowa
Jumper wire
I made a jumper wire out of some speaker wire, and two horseshoe style small electrical connectors, by cutting off 1/2 of each horseshoe. They seem to be plugged in well. Can I leave them in while I start and drive my car?