squarehead

My optispark failed after two years and three months and about 23,000 miles.

I had heard that they usually give warning signs, poor performance, stumbles and missing. Not mine! One second I was cruising with the top down, sunny day, digging the scene with the gangster lean and the next ....nothing. I only know it was the opti after having changed almost everything else and continuity checking each signal and ground wire from the PCM (thanks to shoebox for the diagrams!).

I made the mistake early on of thinking the opti must be good since it was fairly new. The unit that failed had been installed at a good repair shop in town and they had sourced it from Summit and it was a Summit Racing brand opti. I like Summit because of the good prices and super fast ship, I always receive stuff the next day. So when I had narrowed down the failure to opti spark or PCM I ordered another Summit opti (got it the next day!) and I installed it myself this time. What a job, my shoulders still ache from rolling on the concrete back and forth under the car. Well the car fired right up and ran beautifully.

I got to thinking about why the first one had failed. I used to work as a reliability engineer for an electronics company so I performed a rudimentary "failure analysis". I carefully disassembled the old unit until I could see the slotted disk and photo reader and the only thing I could see was foreign material (oily/ grease like smears and droplets) on the slotted disk and around the housing near the optical pickup. I figure the old one must not have been sealed well and possibly failed due to contamination. I got to thinking "I wonder if the new one is sealed well?" (or am I going to have to suffer this same failure again soon!).

I remembered the vacuum line and clean air source tubes I had carefully hooked up to the new opti. If it was well sealed it should have negative pressure in it when the car is running and I should see this at the line back up to the big elbow after the MAF what I am calling the clean air source line. Nothing.... I checked the line to the opti from the engine and it had nice vacuum so no, the opti is not air tight. I checked around the unit with my mechanics stethoscope and I hear a big leak from behind the opti.

I took the old unit and after carefully reassembling it I tested it too and again a big leak from behind the opti. Clearly the bearing assembly on the input shaft from the cam was not a sealed bearing. So the vacuum from the engine that is supposed to keep the opti from having a build up of ozone and provide a purge of moisture condensed in the cap was in reality drawing in dirty air and foreign material from behind the opti mounting plate and cam seal.

It could be that a better (OEM) opti would seal better but for sure I have disconnected the vacuum from this one till I can think of a better way to deal with the problem.

I wanted to pass this on to see what others have observed on the seal of the opti in their cars.

slick1hunting

interesting. I might have to play around with my lines and see if mine is sealed its a delphi


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squarehead

I would be curious to know if your delphi unit seals, I know it is a OEM supplier level part. If it seals well that would make it well worth the additional cost.

I wanted to mention another test I did to confirm the leak on my summit opti. I set up a very light (2-3 psi) pressure air supply (turned way down a good clean compressor) and fed the air to the opti on the car and also to the old part that I had taken out. Both were clearly passing air out of the driven shaft bearing.

I hope others have a chance to read this and post what they are seeing.

ACE1252

I personally would stick with Delco or Delphi for optisparks.

I can't count how many times I've seen people post up with opti troubles and it be an off brand opti(other than OEM sources).

I've had only Delco opti units, but I've had really good results with other Delphi replacement parts. I would be willing to try Delphi if Delco was not available.

squarehead

Ace, there is a lot of wisdom in what you said. Having now gone to the trouble of replacing the opti I wish I had waited for the OEM part.

I saw a link in one of the threads to the delphi unit at amazon for little more than I paid for the summit. I fact Summit offered a good price on the delphi but it was not in stock in Sparks/Reno (overnight to me). But I had time on the weekend to work on the car and was anxious to get my car back on the road.

I am wondering though if the OEM units do in fact seal because on most of the opti threads there are accounts of even the OEM units being short lived.