Hi. I just acquired a 1992 coupe base model and am new to the Corvette world. Its all stock. Has about 149k miles.

The car had been sitting for about 6 months and didn't cost much cause it had some issues. In working on the issues, I put about 150 miles on it. Things I've done for the engine: New battery; changed oil and filter; replaced plugs and wires; replaced air filter; replaced serpentine belt; added 1 bottle of Techron; ran out most of the old gas and filled with 91 octane. Car running good now so I went to get it smogged. Car died half way through test and couldn't get it started again. No CEL. Had it flat-bedded to my mechanic. He's currently pointing towards the optispark. I've searched to internet for replacement info, but pretty much all the threads are at least 2 years old. I'd appreciate it if someone who recently changed theirs could tell me which ones they have had success with and ones to stay away from.

Thanks in Advance.

 

I got my new Optispark from Summit, not installed yet hopefully next week. Might want to get a FSM, I got one mine off Ebay....

 

I got the one for my 92 from the optidoctor. His have a mitsubishi pickup and is upgraded to the vented system.

He sells through ebay and is a member here on the forum.

generation 1 optispark

 

I'd do that, or get the AIP unit from Sac City with venting option.

BUT...you mechanic needs to do real, actual diagnostic work. Maybe he has, but too often people just assume it's the opti and it turns out to be something else. There is a very clear path to diagnosing the LTx ignition system. If the car is still not running, and it is definitely a problem with spark, then he (or you) needs to follow this procedure: https://easyautodiagnostics.com/gm/4...test-the-icm-1. With that, you can confirm the operation of everything from the PCM to the spark plug. And that way, when he changes a part, you and he will both know it is the problem part instead of just guessing.

 

I have been using the Petris Enterprises Optispark for 6-months now. You get brand new vent hoses with a metal filter that they recommend you check every 3-years. This business works with GM and Chevrolet Performance and they specialize in Corvettes. The optispark sensor is said to be of Mitsubishi grade and it is hand built for quality. Just don't open up the case and look at it as this will void the warranty and I am not sure if they used any adhesive on the seal to help make it fluid proofed as much as possible.

This optispark solved the P1371 and P0336 codes I was getting with store brand optisparks and it runs A LOT BETTER than those other optisparks. You can buy a 5-year warranty with this optispark and afterwards, if this optispark does crap out I will see if the "Opti-Doctor" would be interested in fixing it. For now it is quite reliable. I do recommend you liberally glop dielectric grease all over the exterior seams where the seals are between the cap and secondary housing with the metal backing of the distributor. This will further make your optispark as fluid proof as you can possibly make it!

ALSO, check your timing cover seals for any indication if they are leaking and worn out. The seals are cheap enough to buy and there are videos on how to properly install them, ESPECIALLY the seal for the water pump which is the main culprit for optispark oil contamination and which contributed to the serious crap out of my last optispark!

 

Hi all,

I just wanted to thank all of you who have replied. I really appreciate all the input and advise. In my initial research, I did come across all the optis mentioned.

MattthewMiller: Thanks for the diags link. Though the title mentions 1995-05, I would think that the diags points are still applicable.

When I first dropped off my car, my mechanic's first thought was the fuel pump or fuel filter. I didn't ask, but assumed he tested both, and performed other diags which pointed him to the opti. When I talked to my mechanic a couple of days ago, he did mention that he was getting spark from the coil, but nothing coming out of the opti.

As of yesterday, he was going to pull the water pump and check the opti. He did mention that the opti did not look original. He was going to open the opti and check for wear and corrosion.

Question: I may be getting ahead of myself, but want to be ready with a decision. If it turns out to be the opti, is it OK to have him refurbish that old opti or replace the unit? My thoughts is to replace the unit. Especially taking into account the time and effort to get to the opti. Thoughts?

Also, I still welcome any recommendations for a replacement opti.

Thanks.

 

My question, with what items does this mechanic plan to refurbish your optispark with?! He is going to slap on a new cap and rotor and just call it a day without checking if the sensor went bad?! Is he old school? Does he have the oscilloscope and other equipment to actually verify if your optispark camshaft position sensor is working correctly and giving out both clear high resolution and low resolution signals accurately? Will he also replace the internal bearing? If he doesn't have the means to actually test your optispark nor has actual rebuilding components then it is a total waste of time for him to "refurbish" your optispark!

He could put on a brand new MSD cap and rotor and your optispark, after installation with the water pump and coolant added could fail on the spot! This is why so many people just opt to replace the thing if they opened up the distributor and found any indication of engine oil or coolant contamination within it. Ask your mechanic how he plans to "refurbish" your optispark and let us know A.S.A.P. ALSO, have him check your timing cover seals ESPECIALLY the water pump seal! If they need replacing he needs a tool to install the water pump seal correctly. You can't just throw it on or he risks pulling the rubber seal inside out or even ripping the thing on the shaft and it will leak oil on your optispark and ruin a brand new unit! It happened to me by a mechanic's shop time and time again and they still couldn't install that seal properly, I had to, 6-months ago and no leaks!

If your optispark camshaft position sensor has a Mitsubishi logo as part of the plastic molding then it is indeed an OEM GM distributor and it is worthwhile to have the "Opti-Doctor" on ebay refurbish this unit, not this mechanic! If there is no Mitsubishi sensor and it is determined you need a new optispark, the Petris Enterprises Optispark has the price of a Delphi Refurbished optispark but it is worth it in my opinion! The PCM is finicky about camshaft position sensors and if it is not a high quality sensor it will throw codes even though the distributor runs the car!

 

You would have to determine whether or not the Optispark that is in the car is an OEM unit or aftermarket. If it is aftermarket, would the OEM sensors that he uses even fit.

If you plan to keep the car, the ultimate solution is to purchase one, and then if the old one truly is an oem unit, have it rebuilt. Pricey ? Yes. What happens if Brad walks out the door and gets hit by a car ? No more rebuilt Opti's with OEM parts. Then everyone is back to using what is available.

Since I decided to keep my car a long time, I have a rebuilt one to go in when I rework the engine. Then my current one (still working fine) is going to go get rebuilt and put back on the shelf.

 

That's interesting. If there is spark coming out of the coil (not just a signal going into it), then the optical part of the opti (the crank position wheel and optical sensor that tells the ECU when to time the spark) has to be working. So it's down to either the actual coil wire between the coil and the opti, or the cap and rotor. Makes me wonder if the opti that's on there didn't have Loctite on the two screws that hold the rotor on, causing the rotor to eventually work it's way off. If that's what he finds, and if he can find a cap and rotor for a reasonable price, then it may be a reasonable repair to to. I just checked Rockauto and see cap-and-rotor sets for anywhere from $39-$109.

 

I would replace it with a new one. It is a big job to replace, so you don't want to keep going back into it. I use the MSD opti in my 92. It is a vented opti. At one point I found the cap and wiring passage were not sealed well and pulling moisture into the opti. So I seal with sealant and vacuum test before I install all the engine components. Check this thread:
https://www.corvetteforum.com/forums...tallation.html
Also, a problem with the LT1 is when the water pump fails, it dumps water on top of the opti. A mod I do is to install a spigot in the water pump relief hole and pipe it around the opti and below the engine. Check this thread:
https://www.corvetteforum.com/forums...r-lt1-lt4.html
So my advice would be to purchase a new opti with warranty, and a new water pump with a lifetime warranty and do the job all at one time. Then replace the water pump every time you have to go into the opti.
Also, never ever ever wash your LT1 engine.........

 

Here is a thread concerning the MSD 8381 in my car. I am on the second 8381 due to moisture getting into the first one. I am at 155K miles.
https://www.corvetteforum.com/forums...rformance.html

 

That's a good point: for a 1992 it would be worth buying a whole new opti with a vented cap upgrade. There's a lot been written about the MSD units. I'd probably go with an AIP, Petris, or an Optidoctor unit.

 

Yep. I suspect the current MSD's are probably made in China. With Chinese tarriffs, that may come to an end soon. One thing about MSD. You can send a failed unit for test and repair. I have not looked into Opti Doctor.

 

And that's great for an standard distributor. But When you have to drain the coolant, remove the water pump and damper to get the distributor off, you want a reliable part up front. When I was looking I read a lot of post here and MSD seemed to be hit and miss on quality.

 

Optidoctor is NOT hit or miss. Dan

 

Update: Just got back from mechanic. He confirmed that his guys tested the electrical components and the opti is the issue. I and others I know have had work done there before and know that they do good work. So, I’m going to trust that he did what he said.

His suppliers only had the A1 cardone in stock, $300. When I asked his opinion of that brand, he wasn’t too thrilled, but that's all there was.

When I told him I had been doing research, he told me to go ahead and order one. Based on your comments, I priced these 3:

Price Shipping Warranty Comments
Petris $399.99 free over $99 12 months
AIP from SacCity $176.95 $18.75 24 months lowest cost, 2 yr warranty
OptiDoctor $440.00 $25.45 12 months provides test results

The Petris and OptiDoctor are more then I want to spent, but will if needed. I’d like to order one by Monday. Therefore, any additional thoughts/comments would be greatly appreciated.

Thanks

 

Please make sure that all of these have the vented cap upgrade. And you should run that by your mechanic to make sure he's cool with whatever work goes into adding that (I don't know - it can't be too much effort, but it's not in the factory service manual). Given the above, I'd probably save the money and go with AIP. OTOH, I'm comfortable doing this replacement myself if the unit fails. FWIW, the most likely unit to never need replacing again is the Optidoctor one.

 

Good point Matthew. Yes I would purchase the vented one.

Thanks.

 

So that eliminates the AIP

 

I'm glad you pointed that out. I didn't realize they didn't sell a converted version for the earlier cars. Well damn, that eliminates any cheap option.