93 Corvette Opti Spark
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Joined: Dec 2007
Posts: 74
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From: Edgewater Maryland
93 Corvette Opti Spark
New to the C4Scene picked up a 93 with 235k on it. Ran for about a week and then quit. No spark so I am assuming that the opti spark is bad, based on
some thereads that i have read. I am an old school guy with a BLown 69 Z/28, so this is all new ro me. What brand opti spark do you guys use?
I an getting ready to take it apart and see what exactly is going on,
Wayne
some thereads that i have read. I am an old school guy with a BLown 69 Z/28, so this is all new ro me. What brand opti spark do you guys use?
I an getting ready to take it apart and see what exactly is going on,
Wayne
Race Director
Joined: Sep 2001
Posts: 14,674
Likes: 751
From: NEwhere Ohio
New to the C4Scene picked up a 93 with 235k on it. Ran for about a week and then quit. No spark so I am assuming that the opti spark is bad, based on
some thereads that i have read. I am an old school guy with a BLown 69 Z/28, so this is all new ro me. What brand opti spark do you guys use?
I an getting ready to take it apart and see what exactly is going on,
Wayne
some thereads that i have read. I am an old school guy with a BLown 69 Z/28, so this is all new ro me. What brand opti spark do you guys use?
I an getting ready to take it apart and see what exactly is going on,
Wayne
any replacement you buy MUST use the mitsubishi optical sensor and have the improvements ive mentioned above.
I would use optidoctor, he installs a mitsubishi optical sensor into an MSD? Optispark. Im not sure but believe he may add the vent harness to the 92-94 models that didnt have it.
if you follow this advice, the optispark is perfectly reliable.
Melting Slicks
Joined: Oct 2016
Posts: 2,024
Likes: 363
From: Central Alabama
blownz. Don't let the mysterious opti fool you. It's a distributor. You probably are runnung a form of GM HEI on your Z28. it uses a magnetic pickup to determine cam/crank position. The optispark just uses an optical pickup. It's still just a distributor. Bonus is you cant install it out of timing. Only goes in one way.
The issue is, they mounted it on the front of the block under the water pump. There is a special tool needed to replace the water pump drive seal. I 3D printed mine. Since you'll have the water pump off, consider changing out all of your hoses. A full set will cost a little over 100 bucks. If yours are original they are 26 years old and your going to have them off anyway.
Le Mans Master
Joined: Aug 2015
Posts: 6,091
Likes: 1,972
From: St. Charles MO
There are lots of things that could cause a sudden no-spark situation like the OP describes. The opti is just one of them. Others include the ignition control module, coil, wiring (including grounds), and even (rarely) the ECM. I'd suggest a proper diagnostic assessment before throwing parts at the problem.
Safety Car
Joined: May 2001
Posts: 4,754
Likes: 1,642
From: Fairfax Virginia
Start simple and work your way up the trouble shooting list. Don't start at the top and throw parts at the engine!
Do you have the Factory Service Manuals for your particular Corvette? If you do, start at the "No-start" condition and work your way through the list.
belairbrian is correct about the Mitsubishi sensors, they seem to be the "very best" of what is available. On a car that was new to me I would start going through everything and flush the brakes, power steering and coolant before going to far. That is a lot of miles on a Corvette, you will need to be especially careful checking the suspension rubber components. There are so many bushings in the rear of that Corvette that all dry out and fail. I spent over a year upgrading the rubber parts in the rear of my C4. Then I did the front end but that was close to 20 years ago so I may be doing them again. I used Polyurethane Bushings on most of the rear end. I don't know if the rubber parts are even made any more.
If you don't know the age, change the fluid and record it in a log book. The brake fluid especially needs to be addressed as you don't want a brake line failure.... (I did but in my driveway). For me to "Trust" a Corvette I would have to really go through it and be sure everything is "safe", and that takes time.
Best regards,
Chris
Do you have the Factory Service Manuals for your particular Corvette? If you do, start at the "No-start" condition and work your way through the list.
belairbrian is correct about the Mitsubishi sensors, they seem to be the "very best" of what is available. On a car that was new to me I would start going through everything and flush the brakes, power steering and coolant before going to far. That is a lot of miles on a Corvette, you will need to be especially careful checking the suspension rubber components. There are so many bushings in the rear of that Corvette that all dry out and fail. I spent over a year upgrading the rubber parts in the rear of my C4. Then I did the front end but that was close to 20 years ago so I may be doing them again. I used Polyurethane Bushings on most of the rear end. I don't know if the rubber parts are even made any more.
If you don't know the age, change the fluid and record it in a log book. The brake fluid especially needs to be addressed as you don't want a brake line failure.... (I did but in my driveway). For me to "Trust" a Corvette I would have to really go through it and be sure everything is "safe", and that takes time.
Best regards,
Chris
Melting Slicks
Joined: Mar 2002
Posts: 3,108
Likes: 126
From: S.L.C. UT
You want to check for spark and injector pulse. If you dont have spark or injector pulse its probably the optispark. If you have injector pulse and no spark, it probably something in the ignition. Like ignition module, or coil, or something in the ignition system
