Data points are good, and the "which opti is best" never ends so here is one more data point;

My original opti died @~155k, 5 years ago. At the time, I lived in the middle of no-f'ing-where, Colorado (Telluride) and I needed a distributor ASAP so I bought the only thing that was available; a replacement from NAPA. It was ~$500, so as much as any of the "premium" units (I use quotes b/c we know that "premium" units have no better statistics than el-cheapo units -they just cost more). I had low expectations for longevity but it got the car running in the short term.

5 years and ~30,000 miles later, it's starting to fail. The other day while driving, engine "shut off" and simultaneously, the tach went to 0. I coasted to the side of the road, tried to start it, no start. Got out and jiggled the opti harness and it fired right up, ran fine (the wire jiggling turned out to be coincidence). That night I put my scan tool in the car so I could watch low res and high res signals if/when it acted up again. Over the next few days, it "hiccuped" a few times but events were so quick I couldn't see anything except the tach needle "jerking". I knew it was the opti, but wanted to prove it. Yesterday, I was driving home from work and she shut down on me again. Tach fell to 0, and I grabbed the scan tool and looked at it as the car coasted in gear, engine spinning, not firing and tach reading zero. On the scan tool, high res read "0", Low res read "0". Before I came to a stop, car came back to life both signals came to life too and I finished my commute.

Bottom line: 5 years from a non-vented NAPA unit. Not bad....but when you factor in the price, it's not good. I wouldn't buy another one. I'll try a Sac City one next.

 

How about one of these? I ordered one and my MSD in my '92 is currently working, but I only have added 2K miles since I purchased the car a year ago.

 

why not add and vent the one optispark that will last ? NOS OEM

you can find them in junkyards and every once in awhile can find them on ebay (if you know what questions to ask)

 

Price is probably he biggest reason. I don't want to wait for a NOS one to come along is another reason.

I don't mind changing the thing...so I'd rather be CHEAP and change it (if necessary). Obviously this decision is different for others.

 

Hi Tom, so when the hi and low res. are 0 that would mean optical pickup module failure? Would you report back after pulling your Napa unit apart and tell us what you find and if it was a Mitsubishi optical module (I assume it was not)?
I am just curious as it seems the Mitsubishi OEM modules don't fail. But they are also no longer available.

 

That's my interpretation of the data as well.


Sure thing. I agree with you; I also doubt that it's a Mitsu unit. I'll let you know.

 

Thank you!

 

Last time I checked, that little piece of the harness was under $20 and speaking from my own experience, the end that plugged into the opti was badly corroded; replacement was super easy. How many things can you say that about on a C4?

 

Yeah, I WISH it were that, but it's not. It's died on me probably 5 times in the past week now (I'm DD'ing it for the summer). I've established that if you let it sit for a couple minutes, it will fire up flawlessly and you're on your way. The opening hood, getting out, lifting hood, looking, jiggling, closing, getting in...also takes a couple minutes. So it was coincidence.

I can confirm that two ways; 1. I removed that harness segment, visually checked the pins/connector...it was good, clean, nothing bent. I checked both ends. 2. When it starts a couple minutes after dying, I can then jiggle all those same pieces of wire/harness until the cows come home and it won't miss a beat.

I'm pretty positive it's not the wiring.

 

I corresponded via email with the guy that is selling rebuilt Opti's with Mitsubishi optical units that he swaps in on eBay (mentioned in a recent thread here). He mentioned that that cleaning the optical units usually fixed the issue.

He did not say what he cleaned them with though.

All he has available are Opti design 1's. I was looking for a spare for my '96 to swap out the original and put it up on a shelf.

 

I agree with this as I've "saved" two units previously by nothing other than cleaning the lenses. I used tissue paper, brake cleaner, then tissue paper and windex. Worked great.

I might try that w/this one...depending on how it looks when I get it apart. I say "might" just because the nature of my random failures (then starts and drives fine two minutes later) seems more "electrical" failure to me than contamination failure.

 

Tom, do you know if there are actually two optical sensors in the unit? I would think there would be one for each of the low and high res signals.

 

You're right; there is one light and one sensor for each signal.

 

One sensor, two different series of slots in the reluctor wheel. The sensor measures both slots.

Tom, There is a guy on eBay that puts NOS Mitsu sensors in MSD housings. Might be worth a look.

 

I linked that earlier in this thread, but found this person on eBay based on a previous post by you.

 

Yep, Jim provided a link. I saw $415.00.

Maybe I should buy and change just the sensor...

MITSU Sensor

 

You could certainly give it a try for that price. The reluctor wheel is pretty difficult to handle without damaging it in some way (Atleast it is for my clumsy self).

 

Thanks for the information. Curious if its rusted inside (as mine was after around 10 years).

Steve

 

There are two failure modes that I know for the opti: 1) the sensor, and 2) the bearing. I'd be hesitant to replace just the sensor into an old opti with lots of miles, unless you have really checked carefully for bearing play. I think bearings are a bigger problem on motors that see lots of high-rpm use (like mine - autocrossing). So if someone just cruises in their C4, maybe the bearing will last forever.

I'm with Tom: the opti replacement job isn't as hard as the webernets folklore make it out to be, so if you can get away with doing it every five years that's worth saving money on the unit. But on older one I would look into converting to a vented cap. Go through and put RTV on the cap and plate seals, and maybe some silicone grease on the harness plug pass-through, and Loctite Blue the screws for the rotor. The sensor would probably last forever after that. Too bad the bearings aren't replaceable.

 

Ya know I like what the mfr of the Sac City Opti says about thier Opti sensor. To be fair I won't post the mfr name. But for thier pricing I would be compelled to give them a try next time I need an opti. They sell both thier "improved" Opti and a brand new AC Delco unit ($400) - don't know how they are marketing the AC Delco unit with a Mitsubishi sensor unless it truly has one. But they advertise thier Mitsubishi sensor as improved over the OEM unit (which they sell in a whole ACDelco Opti).

Only first hand experience can help here.