IDM acting up in the rain?

[Demian1970]

Anyone know or have any experience with IDM problems in the rain?
My F350 has been running great lately, but last time I drove it in the rain, it "hesitated" a few times. Actually, it felt like it hit a large pothole or something. "Bang!" Then it was OK. A few miles later, "BANG!!" Even worse.
WTF was that? No idea. I was thinking it was the transmission, so I did a fluid drain and filter change. It ran great and I thought all was well.

My wife has it today pulling her horse trailer and she just texted me and said it did it again, and it's raining, so that's the common denominator.
Something doesn't like the extra moisture, and I'm thinking IDM. (swapped out within the last several months)
Any ideas?

[mythreesons]

Sounds like the CPS to me.

[Demian1970]

CPS acting up only in the rain? (it has been replaced within the last year or so, but I won't rule anything out)

[NoRalPh]

Because of where the IDM is located (drivers Ft Fender well, behind the plastic, kinda behind the "F350" emblem), it IS actually prone to moisture problems. Take it out and give it a good look, maybe even open it and look for water inside....

Could also be the connectors going to the injectors, it's @110v and much more prone to "leaking" from the conductivity of the water.

[Demian1970]

The valve cover gaskets/harnesses are fairly new, as well.
I'm hoping it doesn't strand my wife while pulling a loaded 4-horse trailer.

[mythreesons]

When My CPS started going out it would only do it when it was raining out.

[NoRalPh]

Yes, absolutely, and the test for that is Not the moisture, but rather the electrical interference caused by the wiper motor, so if you turn the wipers Off and it clears-up, look to the CPS. This does not seem to happen with the Grey replacement CPS however.


Stumbles when it rains??

[Demian1970]

Well, I'll be dipped...
Thanks!
I just asked my wife it it happened while the wipers were on, she said yes.
She's on a 4 hour trip pulling the trailer and said it hasn't happened again, and it hasn't been raining since it happened last.

I've been a technician for damn long while now, and I never would've figured that out.