car runs great......... when its not raining. I can tell a considerable power loss during a rain and when im behind a car on the highway and being misted with rain from their car. What exactly causes this? does anyone else have this problem? As i said car runs great any other time, but when it rains seems like car is missing but no SES light?

 

Sounds like bad wires, coil, or Opti.

 

what he said....

 

well i figured those were obvious, why only in the rain though? and no SES light?

 

I had a similar concern when it rained but my car would long crank and stumble. When I was installing the MSD opt kit, I noticed that an O Ring was missing between the timing cover housing and the opti. Water must have been seeping in as a mist. It is a 3" O Ring approx.

Runs fine now.

 

Water condensing or misting on the wires, opti or wire terminals will provide a convenient path for the spark to arc to something outside the ignition system, robbing the spark from the plugs. Misting the ignition system with water is a common method for diagnosing misfires due to high voltage arcing. In the dark, start the engine and spray the wires with water mist to see if it induces arcing.

Check all the high voltage terminals on the Opti for corrosion. Check the ends of the plug wires and coil for corrosion. Pull both ends of the short Opti harness and look for corrosion and/or broken pins.

There is no diagnostic in OBD-I for misfires, and no diagnostic that checks the high voltage side of the ignition. Hence, no SES or codes.

 

Good info, thankyou. Im gonna mist water and see if i can see an arc. I did notice one of my plug wires touched one of my pullies and melted away some of the insulation. Im gonna start troubleshooting and change the wires and plugs.