Hey. It started missing then finally broke down and wouldn't start on Saturday when it was raining. Started and idled fine later that day and I drove it across the parking lot. Threw the optispark code (not enough high res timing pulses). The opti has about 400 miles on it. It looks dry from underneath but my guess is it got wet. Ever had any experience with this? I never have. Every time my opti has gone before, it hasn't come back.

The small metal tube on the top of the back half is supposed to go to a vacuum source right? And I'm assuming the black plastic opening on the bottom of the cap is a drain meant to be left open right? I have the back half going to just after the air filter. The filter is just above street level and it does get wet. Water shouldn't get up the vaccum tube into the opti, but I'm suspecting that it did. My last one that failed was FULL of rust on the back half even though I had it sealed up real well. But this one is new. Thoughts? Experience?

 

Check the harness connector at the Opti, and the other end on the bracket on the passenger side of the manifold for water, corrosion or pin damage. Check the plug wire towers for corrosion or moisture.

The bottom connection on the Opti should NOT be left open. If you have vacuum connected to the other port, you will be sucking water directly into the Opti. There should be a blue plastic elbow in the stock rubber air intake elbow, and a hose that connects to the nipple on the Opti, to provide clean, MAF metered air to the Opti vent system. Since you have an S/C, you may need to change that location to avoid pressuring the Opti.

And, on a stock Opti, both the vent connection and the vacuum connection are at the bottom, neither is on the top. Not sure what metal tube you have on the top of the back half.

Shoebox has photos of the correct hose connections:

http://shbox.com/1/opti_vacuum_conn.jpg

http://shbox.com/1/opti_vacuum_hose.jpg

http://shbox.com/1/opti_vacuum_harness.jpg

http://shbox.com/1/evap_sol.jpg

 

Thanks Injuneer. I checked the terminal plug on the opti but not the other end. Hmmm, so I'm pulling water INTO the opti through the open port on the cap half... Is that bad? Just kidding. When I replaced it the time before last I'd had that port capped, but the opti was completely full of rust in the sensor half. All the rust had come off the metal plate sandwiched between the two halves, so when I replaced it a couple months ago I smeared grease on that plate. I figured it was full of water and rust because the front port I had capped was actually a drain opening but I'd capped it. I wonder how the water got in there then?
I think I was mistaken about the metal outlet being on the top half.
This time I'll either just cap the whole thing off like on the unvented version, or I'll run the port I had open on the cap piece to the intake with a check valve so I don't lose boost.
My car is currently broken down in a parking lot. It broke down on the way to work after about 12 minutes of driving, then when I picked it up on the way home it drove fine until it broke down once again after about 12 minutes.

 

The vent system is there to remove ozone. By turning it into an "unvented" Opti, you are promoting rust. Ozone comes from the high voltage spark discharge. Ozone speeds corrosion. Use the vent system the way it was intended. Many people, including myself, have spent serious $$$ converting to a vented Opti.

The most common path for liquid to enter the Opti is through the harness connector tower seal. That's where you need to put a little di-electric grease to prevent leakage.

 

I know about the ozone, but my unvented one lasted over 60,000 miles, and now my vented one has lasted two months. I have the back half vacuum tube going to right after the air filter so there should be a venturi effect pulling a little bit of vaccum. I had that with the front half capped, but again it was completely full of rust after only 2000 miles on it, so how did the water get in there then I wonder? I always have connectors loaded with dielectric, but maybe not enough. Well, I'll get it sorted out.

 

You need to read.

Ozone promotes corrosion. You don't need moisture to make it happen. But water can also get in there and make it worse.

As I already pointed out:
The vented Opti has proven to have a longer life than the unvented version. That's why even MSD added the vent, and why you can find a method to vent an unvented Opti on a popular LT1 Corvette site. Youre recent failue appears to be an anomaly, resulting possibly from failure to run the correct vent system.

Its your car.... run whatever you want. Appears you've already made up your mind.

 

I hooked up the opti vacuum system like it should be. The problem is probably not a wet distributor. The car idles and revs fine until the coolant temp gets to about 180. Always the same temp, then it falls apart missing and backfiring then dies.
I put the scanner on it and it doesn't get bad just as it goes to closed loop like I thought it might have. It would throw the code when I was driving and it died, but the four last times I've started it up and it dies it hasn't thrown a code. It's not the battery cause I put a different one in and no change.