The rain suddenly hates my car

July 30, 2017 7:33 AM

Over the last month or so, whenever there has been a heavy rain, my car has trouble starting; sputtering, stalling, etc. I rev the engine a few times, and eventually it settles down and then will run normally, but this is very annoying and concerning. Any idea what is going on? It's a '96 Mazda Protege.
posted by poppunkcat to Travel & Transportation (8 answers total)

This happened to us also. In our car (94 Volvo 240), this was a common signal that the vehicle needed a tune up. We would take it into the mechanic, pay our money, and it would run fine for another year or so until the rains told us it needed servicing again.
posted by seasparrow at 7:49 AM on July 30, 2017 [2 favorites]

I am one of the least qualified car-savvy people around, but back in the day, this exact mysterious thing happened to my sister's car, and it needed a new distributor cap.
posted by kittyb at 7:51 AM on July 30, 2017 [3 favorites]

Either you distributor cap or starter are probably getting wet. Both are simple fixes.
posted by NotMyselfRightNow at 7:55 AM on July 30, 2017 [2 favorites]

This is nothing serious. I would start by replacing the plug wires and using a dab of dielectric grease to seal the contact, and then move on to replacing the distributor cap. If you change the wires do them one at a time, please and thank you.
posted by ftm at 8:10 AM on July 30, 2017 [2 favorites]

I had this, it was a cracked distributor cap. Once the engine warmed up, the water that had gotten in evaporated and the problem disappeared until then next time water got in - either rain, humidity or morning dew.
posted by neilbert at 8:47 AM on July 30, 2017 [1 favorite]

I had similar symptoms when the casing of the ignition coil in my wife's VW Jetta cracked. Just as with a damaged distributor cap, the fracture combined with a little moisture provides a path for the voltage that's supposed to fire the spark plug to leak out and short to the engine block. As mentioned above, it could also be a bad plug wire or boot.

My uncle, a lifelong auto mechanic, once gave me a trick for finding this sort of problem. Either at night or in a darkened garage, spritz the ignition system with water from a spray bottle while the engine is running. When the spray hits the problem you'll be able to see visible arcing.
posted by jon1270 at 10:30 AM on July 30, 2017 [3 favorites]

On my '03 PT, this happened whenever my oxygen sensor got wet. Turns out that's not an uncommon problem when water gets into the non-watertight connection. Once the undercarriage and connection dried out, the car ran fine again.
posted by Lunaloon at 2:25 PM on July 30, 2017 [1 favorite]

Oh man, I just sold my own '96 Protege last week. Whenever I had problems starting, it was battery-related. My battery had a lot of corrosion, and the rain would exacerbate it. I dealt with it for years, and then once I was at an AutoZone and the guy told me about some corrosion scraper-offer compound. I of course don't remember the name anymore, but if you pop your hood and see some corrosion on your battery cables, take it to AutoZone and have them take a look. Even if it's not that, employees at AutoZone are usually pretty knowledgeable and can point you in the right direction (and possibly even fix it themselves on the side).
posted by kevinbelt at 5:35 PM on July 30, 2017 [1 favorite]