I've had my 04 for a few months. Shes got 124k miles and I've added about 1k. She's idled a bit rough since I got her. Rpms are at about 750.

Today I went through the car wash - typical automatic style where car is in neutral and it pulls u through brushes, water, suds and a dryer.

When I exited, the idle was smooth as silk. Was still at 750 rpms. I had to keep checking to see if car was even running. I loved it, but it only lasted about 10 minutes and gradually became rough again. Obviously the wash did something that wore off.

Any ideas??

 

Do you say the engine idle has been rough. Has the Service Engine Soon light been on?

 

tune up recently ? plugs wires maybe coils, check for vaccum leaks etc

 

yes, it's idled rough since I bought her a few months ago. But became smooth as a new car the second I left the car wash. Then rough again 10 min later.

Service engine light has been on for months, due to thermostat code P0124. Not related. (Edit: Correct code is P0126)

 

isn't P0124 a Throttle Position Sensor code? it might be related.

 

I might have typed the wrong code in my first post. ill confirm later today. (Edit: correct code is P0126)

 

Possibly cooling related, ran smoother when being sprayed with cold water. lower intake air temp, Radiator cooling more?

 

I dont think thats it. per the Ultraguage, the truck runs cool at 175 to 180 degrees. 188 at the highest.

 

Try it again. See if you get the same result or was it just a coincidence. Check to see if you're getting any water in the engine compartment after the wash. Hard to see how water anywhere else would make any difference!

 

This is the first time it's ever idled smooth in the few months ive had it. Now that the car wash "knocked it" smooth for those 10 minutes, I know it should be smooth. Something is wrong with it.

Any idea what a car wash coulda done to temporarily fix my rough idle???