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Misfiring on humid days?



I have a 96 GMC Sierra with a 350 and am having a problem with the truck. the best way I can describe it is a misfire or sputtering but this only happens on days that are either raining or threatening to rain. The computer was throwing a code for the O2 sensors and the cam position sensor. I replaced the O2 sensors and that code is gone now and while I was at it I put new spark plugs in. I have not adressed the cam position sensor problem yet but from what I understand if the distributor gear gets worn it will cause the computer to throw the cam position sensor code. Will this cause the misfiring on humid days only? The truck runs like a dream on dry days. Any help I can get would be greatly appreciated. Thanks

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Ok. I went out last night and sprayed water on the sparkplug wires, distributer cap and coil wire and there it was. Two spots on the coil wire started arching. Today I changed the Plug wires, cap and rotor. Since I just changed the plugs a few days ago I saw no need to change them again. We are expecting rain this weekend so I will keep you informed to let you know if the problem is gone. Thanks.

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Plug wires!


Take a old plastic spray bottle fill with water, With engine running (warm but not hot) start misting (spraying ) 1 wire at a time from the boot on the plug up to the dist. cap.


If you have a bad wire it will arch and cause a miss.


Then check the dist cap


Do it when it starts to get dark for a light show.

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