5.0 Idle drop when it rains

[bkolnz]

Here's a good one... Bought a '98 XLT 5.0 about two months ago. It rained on the vehicle for the first time about 2 weeks ago and I noticed that the RPM's dropped to 500 at stop lights. The AC won't function at that pace, and in Texas, that's a big deal. The ECU threw a code and I thought I had a BIG problem. Later that day the rain stopped, dryed out, the CEL went out, and the idle came back to a normal 900 or so. Today we have leftovers from Ike in town and had to make a run of about 1 hour. At a stop light noticed that the AC was blowing hot, and the idle was down to 500. Is this a ICW issue? or something more involved that is sensative to Humidity?

Bill in Euless,TX

 

[Wray-Wray]

vacuum leak maybe? what code did it throw? alot of things can throw off idle any other symptoms other then those?