I have a 1999 Accord with 125K miles and I am trying to solve a problem that my mechanic and I have been working to solve. When it rains, I sometimes have trouble getting the car to turn over first thing in the morning and when it does start, the car will sometimes hesitate or even stall out after I drive a short distance. (Of course every time I drop the car off at the mechanic he has yet to experience this and I even let the car sit at his shop overnight to see if a cold, wet night might reproduce the condition.) In my experience, once the engine is warmed up, the car seems to run ok. Except for last night when I left work. It was pouring down rain when I started the car, which by the way, started right away. But after driving down the highway at 55 mph for about 3-4 miles in the pouring rain, I could feel the car misfire 2 or 3 times to the point where I felt the need to downshift (5 spd manual) to prevent a stallout. This morning the car started right away but stalled out going 25 mph up a steep hill about 2 miles into the morning commute. It was wasn't raining this morning but it had rained hard the day before and car body was covered with condensation and rain water. Any ideas on what this could be? Could it be water getting into the distributor and then the engine eventually drying out the moisture when the engine temperature goes up?

 

Yeah it could be.

My trick is to look for arcing in the dark. Complete darkness, like a garage where you can turn off all the lights & away from streetlights.

Water makes it more visible, so have a windex bottle with water.

Start up the engine completely cold, turn off all the lights & look for arcing, or a dull blue glow around the wires or distirbutor. If the engine is damp, all the better to see the arcing more clearly.

Your spark can leak through microscopic cracks in the insulation, or flash across microscopic defects in the surface of the distributor cap. You aren't gonna measure that by checking the resistance of the wires with an ohm-meter. You need special expensive equipment to duplicate the high voltage so it's easier to watch for it with the engine running.

 

Thanks JimBlake. If I do see the arcing, what is the repair?

 

Replace whatever part. For that high-voltage stuff, you aren't gonna "repair" it, for example you can't patch the cracked insulation of a spark plug wire. It's not worth your time to try to repair the smooth surface of a $15 distributor cap.