I replace IAC now idle too high

Wondering if I did something wrong or did the replacement show a different problem. It was surging slightly when at idle with foot on brake. Idle was about 600 rpm. Removed the IAC.. wasn't real bad but since Had a new one and new gasket I put them on and cleaned the throttle body which wasn't all that bad either. Some sooty tho. Now all cleaned up and it no idles at 1200+ in neutral. The cables have a bit of slack so I don't know how to get the idle down.

 

600 RPM sounds good, why did you replace IAC? Surging to me says vac leak. Have you cleaned MAF? Was the IAC new? this is the problem with throwing new parts on, it is a guess to the real problem.

 

This is a “normal thing” the high idle should come down after running for awhile. At least it has happened to me a few times. Since you put in a new IAC, it might take a bit for the computer to learn or set it. Id give it 15/20 minutes of run time

 

Did you reset the ECU and give it time to readjust to the new components? How long after you start the truck are you taking your idle readings?

Until the truck is warm, and the IAC is doing it thing based off water temp, the idle is generally higher.

 

I did reset the ECU. Drove it to town and back which is about 40 miles round trip. When I pulled to a stop in the driveway the rpm stayed at about 1200 on the dash tac. with truck in park.

 

I think Mike @Digiratus experienced something similar, but I forget exactly what he determined and how he got back to his happy place.

 

Do you know if all the ECU checks have been completed? IE, do you have a code reader that will tell you that? My ECU sometimes won't complete the checks for 60 miles or so.

 

I just had the same issue and discovered that the end of my PCV hose wasn’t connected to the plenum. So maybe just double check all your hoses are on even if they weren’t involved in removing the IAC?

 

My code reader only shows codes and clears them. So I don't know.

 

I put it back in barn. I'll check those hoses again today