Car acts up when it rains?

Messages
180
Location
Upstate NY
'03 Hyundai SantaFe, 2.4L engine. This is the wife's car. We've owned it since Feb. After we purchased it it had a problem where it would loose power and would ocassionally surge/stutter while at idle/low speed. It was determined (by the dealer) to be a coil pack that was failing under load causing misfires. The coil pack was replaced and we haven't had any issues in nearly two months. It was raining last night and this morning - the car acts up again, same symptoms. Why would humidy cause this? How would humidity cause this? Or, is this most likely a coincidence? I know humidity can cause problems cause a friend has a Saturn Ion ('04) that doesn't start reliabily when it rains. No problem any other time. Thanks
 
Messages
15,056
Location
Canada
It shouldn't be a problem with modern FI cars. I had a 1986 Honda Civic that barely ran while warming up in ANY kind of damp weather. Had everything igntion related replaced, and in the end was told 'carburated Honda's are just like that, get used to it'.
 
Messages
4,998
Location
Milwaukee, WI
Moisture affects the way that electricity travels through air. More humidity makes it more difficult for electricity to jump gaps. This is why poorly sealing distributor caps case problems. My hunch would be that there is a break in the wiring in the coil somewhere. The heat burns out the moisture once the car is up and running, but when cold and wet it's causing some arcing. You probably won't see this, but it's worth taking a look under the hood in the dark and see if you can find any arcing.
 
Messages
2,439
Location
snowblind in TX
 Originally Posted By: bepperb
More humidity makes it more difficult for electricity to jump gaps.
Just the opposite. Moisture/humidity/condensation gives electricity more paths to travel. Ignition sparks find all kinds of ways to bypass the plug gap and jump to ground. EDIT: I see your point, we might be saying the same thing.
 
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Messages
25,045
Location
ON, Canada eh?
When was the last time you had the plugs & wires replaced? These engines are very fussy with spark ignition if the plugs/wires are worn. Or if the plugs are the wrong type or improperly gaped. If the above is a problem it could have caused your coil packs to be stressed and run hot until they were a problem. \:\!
 
Messages
19,479
Location
Chicago Area
Damp problems like this are almost always ignition. Wires and plugs are the other parts that need to be replaced. But misfires can puke a coil, even your new one. Use boot grease on all connections and the wires.
 
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