Car shuddering after start if it rains

I’m having a periodic problem with my girlfriend’s 1998 Chevrolet Malibu. One of my spark plugs misfiring after it rains for an extended period of time. If I stop the car and then restart it the car will run normally.

I have already replaced the spark plugs/cables. Any ideas would be helpful.



I’d wonder if you have specific knowledge that it is “one of the spark plugs” - i.e. do you actually have a misfire code that specifies one cylinder or something?

Anyway, seeing as you have done the plugs and wires I’d mention just a couple of things about that - first, cheapie spark plug wires are not necessarily reliable. If you bought bottom shelf wires don’t assume they are ok. Second, if you haven’t done a lot of plugs/wires it is pretty easy to not get boots fully seated onto plugs. One should also apply dialectric grease as this helps seal out moisture and other gunk (in addition to keeping the boots from sticking).

But really I suspect that you just need to move on to another part of the ignition system - you may have a bad coil.