misfire during rain

[hodges69]

2004 Mercury Mountaineer -150,000 miles
Just replaced all plugs and wires and a new coil. Mechanic said smoke test was negative, but it still misfires but only when it rains. Are there other wires that could be exposed and shorting?

Please help?

 

[rfe]

we had misfires after 2005 Mountaineer rig sat in rain for couple weeks...
mechanic said water somehow got in...runs down and collects in the tunnel ? above the spark plugs..they removed the water, no more problems...
this is Washington state in a rainy spring...

 

[hodges69]

Thanks.

I'll look out for the tunnel. I have also noticed that the misfire occurs even in very light rain or even before it's about to rain - certainly not enough to get into the engine. It's almost like the engine senses high humidity

 

[01sporttracguy]

ya thats what i suspect as well rain loves to drip in those tunnels the best thing that worked for me was put grease inside spark plug boot and make sure they are seated all the way down let us know if that works