Trying to help a friend

[bdw18_123]

I'm thinking Opti as well. I used to have a '93 6-speed LT1 Corvette and I had a very similar issue. Back then, I also initially ruled out the opti as a cause of the failure because I too had replaced the opti a few thousand miles ago at the time.

The Optispark units in the '92 to '94 LT1 Corvettes have such a high failure rate because they do not have an active venting system to remove the buildup of moisture which leads to corrosion and eventual failure of the unit. In the '95 and '96 LT1 Corvettes, GM changed the design of the optispark unit and added the active venting system.

The aftermarket opti that I had purchased went bad because I sealed up the seams with RTV and the corrosive gasses (and condensed moisture too, I'm sure) stayed in and took out the optical portion. But even if you don't do the RTV thing that I did, the opti will sit have a very high chance of failing if the active vent system mod is not done. That opti I bought came with a warranty, so I was able to get it replaced for free. I also purchased the '95-'96 style of opti cap with the hose nipple for the vent hose so I wouldn't have to glue in one like is described in the Corvette Fever article I used (see CF thread linked to below).

Here is a link to a thread where I described my problem in detail and what I did that ended up fixing the "cranks, but doesn't start" problem:

http://forums.corvetteforum.com/c4-t...ral-times.html


pcolt94's post in the middle of the above CF thread is a really good one for understanding the role that the ICM and coil play in the sparking system, which helps to narrow down the source of problems with the spark system in the Corvette LT1 engine.

I just edited my last post today in my old thread I linked to above because I never posted the update I promised in that last post.

[Schrade]

If it started up after cooling off, I'm guessing NOT opti-spark.

Opti laser (or whatever the 'light' reader mechanism is), gets fouled by dirt, and occasionally coolant. I don't think a cool-off will allow a fouled opti to read better.

Lotta' snappics here:
http://forums.corvetteforum.com/c4-t...rs-needed.html
(thread I got CF mods to merge with another CF'er, with identical problem...



Did VATS problem get addressed by GM prior to '95?

Sudden shut-off (was he at speed?) seems HIGHLY likely a hot ignition module, which would NOT allow a code to set.

Does he have SES light???????