03', F-150, 4.6/auto, 167K

I removed the throttle body and cleaned the carbon out of the two ports leading to the EGR valve after getting the po401 code. I also cleaned the entire TB spraying TB cleaner into all of the ports I could find, I did not replace any parts just cleaned everything, now when I start the truck the engine starts idling at 1100 to 1200 rpm before dropping down to the normal 750 rpm, anybody know what's causing this?

 

I don't know if anyone else's 5.4 has done this but on my truck it does the same thing as what you describe, the only difference is that mine's been doing it since I got it. I always thought by doing this the truck is just "warming up". Mine idles at a 1200 rpm or so then settles down to 7-800 rpm. I normally wait till it drops before I start driving.

 

did you take off the negative battery cable? I heard on here that you need to take it off for 15 minutes for the computer to reset after you clean up any parts of the intake.

 

That's normal if it lasts for a few seconds then goes down to 700-800.

 

I agree, your truck is running normally. It seems like your high idle may not have been working prior to the cleaning and that cleaning it has restored the function.

 

After driving the truck today I relized that my idle is all over the place, after starting cold the engine runs at 1200 rpm then falls to normal, after it has warmed up than been shut off and restarted it starts out idling at about 950 then falls to normal. Is there a senser that controls idle speed?