it never fails...any time we have a torrential down pour i get a misfire. this time its number 6...before its been number 3

any thoughts??

 

Year, make, model, engine?

If it's a 5.4L with COPS, then the issue is the rubber boots for the COPs losing seal to the spark plug wells and allowing water down next to the spark plugs.

 

sorry 05 5.4L....how in the world does the water get all the way in there?

 

Pop the hood and inspect the cowling weatherstripping. If it's torn up or missing you will get water dropping straight onto those cylinders. Also check the condition of the sparkplug to coil boots and use some dielectric grease in the boots to help seal out moisture.


-Mike

 

My 2005 would do the same thing. When it rained hard I would get a misfire,or if I would take a long trip the engine would start to jerk and jump. I installed all new spark plugs and plug boots. Mine had 124000 miles so it was way over due, but now it runs perfect