Misfire After Rain Storm

[pzy3339]

I believe I have seen it mentioned before but I cannot find it at this time.

It rained pretty hard all morning and now I have P0308 and a rough running vehicle. Cylinder 8 misfire. I have heard this can be due to water getting in the 8 cylinder's spark plug hole. I have not had time to investigate if this is the cause but I would like to get a head start on finding out what people have done to fix this problem so it does not happen again.

Thanks,

Josh

 

[DavidEBSmith]

I had something similar happen. Swapped the coil from the misfiring cylinder with the one next to it and the code moved along with the coil. Replaced the coil and all is well.

Don't know if it was coincidence that the coil went bad after the car sat out in the rain all night, if water got into the coil and killed it, or if water around the plug somehow contributed to the coil dying.

 

[pzy3339]

The plug well was indeed full of water. It rained pretty hard all morning. After pulling the coil and drying out the well it took about half an hour of driving for the coil to start working properly again, it now works but not quite right. The truck has been in need of coils for a while i think. it will buck a bit at a few spots. Might be time to just replace them all.

Still wondering what to do to prevent the well(s) from getting water in them in the future. Might have to make some type of cover for the intake manifold.

 

[Explorer_PL]

I installed a piece of aluminum gutter/trim running across under the windshield. Problem solved, somebody else had a metal shop build a custom one, same concept but much nicer.

 

[pzy3339]

I installed a piece of aluminum gutter/trim running across under the windshield. Problem solved, somebody else had a metal shop build a custom one, same concept but much nicer.

Good to know. I think I might try to make one out of carbon fiber or fiberglass. I looked up a thread you were in on a while back about the issue. It leaks through the stupid clips as I suspected. I think I am in the short term going to find some type of silicone sealant or something to waterproof the clip holes until I can fab up a nice piece of something to run across the top of the firewall.

Thanks

I am also probably going to be replacing all my coils with MSD blasters. It would seem my coil was damaged by the water. It idles fine but does not get up and go like it should now. Feels like the timing is retarded and tries to advance but always backs off right away because the coils are not strong enough anymore. Just a guess.

 

[jseabolt]

I installed a piece of aluminum gutter/trim running across under the windshield. Problem solved, somebody else had a metal shop build a custom one, same concept but much nicer.

I've had this same thing happen to me (twice) but there is a much easier solution. There are four drain holes in the cowl panel lip. Two of them are above the rear spark plugs. Two are on the ends.

I took some alumnium tape and placed it on the underside of the holes above the spark plugs. I have not had a problem since.