Help! Rough idle in rain

[03 explorer]

HI I am new to this forum. I found this website searching for ideas on what could be wrong with my explorer. To make a long story short I bought a 2003 Explorer v6 3 weeks ago and when it rained the first time and I was stopped at a red light my explorer started idleing rough and rpms would drop 300 to 400 and it would rev back up. I replaced spark plug wires, plugs, coil pack and fuel filter. I took it back to the dealership I bought it from and they cleaned the IAC and throttle body. Tonight it rained again and it still has this problem. It has not done it when it was dry out. Does anyone have any ideas what else I could check? Thanks for any advise!
David

 

[BrianDye]

Is your air filter taking on water somehow?

 

[zerodevil]

my guess is either there is water getting into your air filter, or water is interfearing with your ignition system. are the wires and boots sealed up tight? does the vehicle still have its wheel well pieces? hitting any big puddles?

 

[03 explorer]

The air filter isn't wet. I am not hitting any big puddles. It seems to be more from the moisture than the water. It still does it even after it rains, as long as the air is still moist feeling. The mechanic at the dealership defined it as "searching for idle". I showed him a video of it on my phone. But of course it wouldn't do it for them.

 

[High_Order1]

My Moms' Escape did the same thing. Didn't even have to drive it. If it rained, it ran like crap. Then, as mysteriously as it started, it quit on its' own...

Shawn

 

[mikeinri]

On past vehicles I've owned, this has always been an ignition problem (cracked spark wires, distributor cap, etc.). I know you've replaced a lot of that already.

Do you have any suspect vaccuum lines? How about any electrical parts leading to the coil pack? Computer OK, etc.?

Mike

 

[03 explorer]

I looked over the vacuum lines and also the wiring. I did not find anything that looked to be bad. I am going to look it over again tomorrow to see if I can find anything. I made an appointment at my local Ford dealer to take it in on Tuesday morning. They are going to do a diagnostic test on it and also upgrade the pcm if there are any available for it. Does anyone have any other ideas on what I could check for tomorrow when I take another look at it? Thanks for all the help!

 

[muzzymaniac]

Tonight, when its dark, go outside armed with a spray bottle filled with water. Start the truck, open the hood and start misting around the wires, coil and plugs etc. Watch for arching. Trace any arching back to it's source. No arching? Start spraying around vacuum lines and such and see if there is any change in idle. Don't forget to spray around the TB and intake. This has worked like a charm for me in the past!

 

[03 explorer]

I just got my Explorer back from the Ford dealership. They did a few upgrades on the pcm one was an upgrade for surging idle. It seems to idle smoother now. They tried spraying it with water to make it act up but they could not get it to do it. They thought the upgrade would take care of it. I guess we will have to wait until it rains again to see if it does it. They want me to bring it back in if it does it again. I will post with an update after it rains. Thanks again for all the help!

 

[03 explorer]

Today was the first day it rained since I got my explorer back. It does the same thing as before but worse becasue now it actually dies. I took it straight to the Ford Dealership like they asked but there were no service people there becasue it is the weekend. I have no clue what to do anymore. I already have 500 dollars into this thing in the last month and do not know how much more I should spend before I give up. Does anyone have any other ideas? Has anyone else had this problem?

 

[BrianDye]

Tonight, when its dark, go outside armed with a spray bottle filled with water. Start the truck, open the hood and start misting around the wires, coil and plugs etc. Watch for arching. Trace any arching back to it's source. No arching? Start spraying around vacuum lines and such and see if there is any change in idle. Don't forget to spray around the TB and intake. This has worked like a charm for me in the past!

I was gonna say, try spraying certain areas and see if you cant narrow it down, that should be a big help to the dealership to figure something out, they probably just wet the truck down with a hose and called it a day

 

[tonydp]

Try pouring water on the windshied with your hose and see where it ends up under the hood. My Lincoln used to drip from the cowl onto the cop and all he'll would break loose. Nothing black silicone couldn't fix. Just a thought