I have been reading a lot about the (ABIT's) or opti spark lately and i have a question. Most information i have read describes several different fail points of this design but i cant seem to find much information on the optical sensor its self. On an OEM Delco opti with the Mitsubishi sensor, how prone are these to fail? From what i am reading the majority of failures seem to be caused by ozone and water/moisture entering the unit but information as far as the sensor failing seems to be limited. Like i said, i am just curious to know others opinions on the sensor inside the unit and what your thoughts or experience is regarding the failure of just the sensor....The information i am reading, is it correct as far as the majority of failures is caused due to ozone and or moisture and not the sensor or is the sensors also a big part of failures. Any info is appreciated!

 

The ozone causes rust, and the rust particles blind the emitters/receptors in the optical module. That's what did my original unvented Opti in at about 40K miles. Might be able to clean it, but I never tried.

GaryDoug took a Chinese rip-off optical module apart, and found that it was sloppy solder joints on the printed circuit board. When the unit got hot, parts expansion caused the connections to move, and broke contact in the soldered joint. Repaired it and it worked fine.

In general , the Mitsubishi module seems very robust.

I don't know where MSD gets their modules, but over the years I've analyzed some data logs of cars with weird RPM surging problems (sudden swings at idle upwards of 1,800 RPM), and narrowed it down to the optical module (process of elimination - can't say what within the module caused the sudden RPM spikes). In one case, the unit had just been returned to the owner by MSD after a "rebuild", and it was still defective.

 

So far I have only seen one failure of an optical module (not Mitsubishi) and it was for one of the optic receivers (transistor). All others have been loose solder connections. Most of the non-Mitsubishi "modules" are not exactly modules. They are usually a couple of separate circuit boards inside the case with conductors between them.