Question for the C4 Owners. The Optispark Module, considering the vehicle is a 94, garage kept with low miles, 30,000, how long is the original Optispark Unit expected to last? I had one fail now and was wondering. Is there any reason for it to just work fine one day and fail the next?

Appreciate your feedback.

 

I also have a 94. I’ve owned it for 17 years and have replaced the opti spark twice over the course of the 19k miles I’ve put on it since I bought it. In my case it was a leaking water pump that took it out both times. You can have a very slow leak from the water pump that doesn’t even make it to the ground but it’s enough moisture to kill the opti spark.

I believe it was just time and old age that caused the water pump to leak.

 

The previous owner of my 94 had the original Opti fail at about 45K in 2012. . He replaced it and installed an electric water pump.

 

Back in 2013 I bought a 94 that had 103k on it at the time. I bought thr car with a crank no start and found the optispark unit to be original. I replaced it due to it being difficult to spin the stub shaft in the opti. The opti was still operational but I replaced it as a while I'm in there doing the water pump, I should replace the opti. The issue ended up being a dead coil and not a failed opti.

Many factors will determine the lifespan of the opti. The largest factor I've seen is moisture intrusion. Either a leaking water pump, people spraying their engine with the hose or lressure washer when cleaning it or the car sitting somewhere damp. Be it outside on a non paved driveway or in a damp.garage or building.

 

Lifespan of the opti is a crapshoot, especially with the first-generation units that were used on Corvettes from 1992 through 1994. The second-generation units that were used on the 1995 and 1996 Corvettes were significantly improved, and tend to last much longer. Possibly the most helpful change in the second-generation units was the active venting that was implemented. It draws a small amount of filtered air from the intake bellows, downstream of the MAF, through the body of the opti, and from there into the intake manifold. This does much to purge condensation and corrosive ozone from the unit. The first-generation units were passively vented via weep holes at the lower edge of the unit, and this arrangement proved to be inadequate, thus the addition of active venting in the second-generation units. It is possible to add active venting to a first-generation unit -- search the archives for info about implementing this if you care to do so.

To add a single data point to the discussion, my '94 had only 19k miles on it when I bought it, and within weeks the opti began misfiring. I was fortunate at that time that DynoTech Engineering was still offering their Dynaspark unit. I bought and installed one, and it has performed flawlessly to this day.

One of the major problems with replacement units these days is the lack of availability of the original Mitsubishi optical sensors, which were quite reliable. The generic "brand X" sensors that are currently available seem to have a dismal reputation for early failures. If you didn't already dispose of your original unit, keep it in your stash of parts. The Mitsubishi sensor, alone, has value.

Live well,

SJW

 

Yep crapshoot had a 95 37,000 miles OPTI went bad , got a 93 120,000 removed the OPTI had pic can't find it ,rust inside taped it on table got a spoon of powered rust fell out ,looked like hell DA DA 93 ran great ????? These things are weard .. I guess I should just put it back ,I wonder ..

 

All good info here. Just want to add my take on the opti. Some of the failures can be prevented. First, parts store optis with the aforementioned brand x optical sensors are mostly garbage and are the cause of a lot of “opti bashing.” If you replace, replace with a quality unit from places like Petris, and while you’re at it, upgrade to the vented version if you have a 92-94. Leaking seals and water pumps are major killers. Replace your seals if you haven’t. At 25+ years, yeah they’re shot. Have a low mileage car….shot, possibly worse than a car that’s been driven. Replace the water pump and tap the weep hole for a fitting. Run a small line from the fitting down past the opti. If the water pump internals start to weep, it will **** on the ground and not your opti. Even AC Delco pumps are made in china now. Another crapshoot. By a flowkooler pump, made in USA with billet wheels and quality seals and bearings. Or go electric. Which is a whole debate in itself which is better. The electric does eliminate the pass through driveshaft and seal in the timing cover, but then the hole has to be either welded or plugged somehow. A well protected, quality opti should last and not be such a crapshoot. The opti distributor was a great idea with having direct drive right off the cam, but it’s hard to access and is in a vulnerable spot. There’s a reason why the Gen 2 small block lasted only 6 years, but they are great engines with reverse flow cooling.

 

the title says it all, Installing Torqhead 24x now and turned the project into “since I have it up on stands” getting ready to ship headers to jet hot.
Ordering a smaller hi-torq starter to clear the ARH 3” SS exhaust, might replace the radiator since I will be adding an electric water pump powered by air pump connector. Noticed some corrosion when replacing knock sensors and evidence of brown sludge r/t dexcool, car was green and clear when I bought it 40k mile currently.