Car wash messed up idle

J

johnaec

Registered
I took the Mark to a touchless car wash yesterday that I've often used before with no problems, and ever since yesterday's wash, my idle doesn't want to return to normal. It starts at 2000rpm, and SLOWLY drops - it still does this after a day and more than 30 miles driving, even when completely warmed up.

The engine wasn't washed, (hood never opened), and I looked soon after the wash, and the top of the engine was completely dry. The car just went through the spray building, then they hand towel the whole car off.

The wash DOES spray up from the bottom, and I'm leaning towards the possibility the bottom spray knocked a connector or hose off somewhere. I'll put it up on jacks tomorrow to look, but does anyone know the likely source of the problem?

John
'97 Mark VIII LSC
'96 T-Bird 4.6L
 
RE: Car wash messed up idle

Could be a vacuum leak or a bad IAC motor. When you said "carwash" the first thing that sprung to mind was the coil packs, but if it's higher, and it's not running rough, that's probably not the problem.
 
RE: Car wash messed up idle

A little more info - when cruising, it doesn't want to drop down right away when letting off the throttle. It's acting like there isn't a throttle return spring or something. Hopefully the source of the problem will be obvious when I get it up on ramps tomorrow...

John
'97 Mark VIII LSC
'96 T-Bird 4.6L
 
RE: Car wash messed up idle

Well, whatever it was, a few more days of driving and resetting the computer seems to have pretty much resolved it.

The funny thing is that clearing the computer, (disconnecting the battery), by far made the biggest difference. It's like something at the car wash caused the computer to recalculate something about the idle curve...

John
http://mark8.org/users/johnaec/Mark_VIII_s.jpg
'97 Mark VIII LSC
'96 T-Bird 4.6L
 
RE: Car wash messed up idle

Was it the type of car wash that has the "blow dryer" at the exit?

"sometimes" mine will start to idle funny as I pass thru the dryer.
Once, my car died..

I'm thinking that the blow dryer is freaking out the sensor that reads barometric pressure.

I could be wrong.. and i'm just speculating.
 
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