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Car misfires when wet outside?

2004 Kia amanti. Why does my car misfire when it’s raining and humid out? The misfire goes away after two minutes of driving but only when wet out. Whats the moisture getting into?

Here’s an image of my windshield missing a piece of it’s barrier.
Also you can see moisture inside of the engine by the abs and iac

Water’s getting into the ignition components - how old are the cap and rotor (if it has them), and the spark plug wires?

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I don’t know if my car has those :disappointed_relieved: for the spark plug wires, I don’t know when the last owner replaced them. How do I know it’s not the coil or something else?

That’s possible, but let’s go with the cheap options first. If you don’t know about them, then maybe it’s time to have the spark plugs, ignition wires, cap, and rotor replaced. That’s normal maintenance on a 15 year old car.

@texases Id prefer not to do a tune up if I potentially don’t need one. Maybe I can try and spray some Misty water around my plugs and wires to see if I can narrow things down. I hate the idea of spending money for parts if that’s not even the case

If you don’t know when the last time you had a tune up, why wouldn’t you want to take the car in & find out if you could use one? Or find out what needs to be repaired. Its for the better of your car and piece of mind. I wouldn’t call that a waste of money.

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If you purchase a car used and don’t know when it was last tuned, it definitely is not throwing money away by doing a tune up. If you do the tune up and the problem persists, you still have the satisfaction that you didn’t waste any money because a properly tuned car is a good thing. If you still decide to mist the engine it’s a good idea to do it in the dark so you can see sparks from bad wires.


Update; went ahead and sprayed water and the coil seems to be sparking!

Misfires in damp weather is usually dampness (which might be nearly invisible) affecting a high voltage component, coil, spark plug wire/boot etc. So whatever the problem is , it is almost certainly limited to the high voltage components of the ignition system. Many years ago I had a VW Rabbit that would stall out every time I ran over a big puddle. If I waited for 15 minutes then it would start and run fine the rest of the day as long as I didn’t run over another puddle. On the weekend I’d spray the engine compartment high voltage components from every conceivable angle with a garden hose to try to determine the problem and never got it to even hiccup, let alone stall. Next puddle, stall. So I bit the bullet and removed the coil and bench-inspected the case. Sure enough, a tiny nearly invisible crack in the ceramic underside. After a new coil installed , no more puddle-caused-stalls.

Replace the coil on spark plug boots.,2004,amanti,3.5l+v6,1440626,ignition,spark+plug+/+coil-on-plug+boot,10150


The spark is sufficient when all the other conditions are perfect, but once rain or moist air steal additional energy via the old spark plug wires, the engine starts misfiring . … But when the engine gets cold, the moisture re-condenses inside the distributor cap, and on the next rainy morning, you have the same problem.