01 4.6 high idle

[Taxman]

I am trying to help an employee fix her Expedition. All of the sudden the idle went to 2000 and stays there. She replaced the IAC without any change. I checked it by unhooking the harness and the idle drops and then dies, so its not stuck open. I kept it plugged in and unhooked the hose and pluged it and it died.

So it appears that there is something telling the IAC to stay wide open. We don't have a computer to plug into it and she cant afford to go to a shop, so any help is appreciated.

Thanks
Johnny

 

[Bedrck47]

How many miles on the expy?

Is the check engine light on?/

 

[Bedrck47]

check to see if the throttle plate is going fully closed

 

[Taxman]

Not sure on the miles, but I assume over 150k.

The throttle plate is good. I had already cleaned that when I was chasing a bad idle and no power problem. That was a bad fuel pump.

She also has the bad coil connectors which makes it idle a little rough and has some missing sometimes. I'll fix that for her when it can be afforded for me to get the connectors. But this idle thing just jumped up about 3-4 days ago and wont go back down.

 

[Taxman]

Oh, and yes the light is on. Been on, its due to the coil connectors I think. Codes for misfire. But again, that's been there before the idle issue started. She has not taken it to get the codes checked this time yet. I told her to get them checked and we can see if anything new has popped in there.

 

[Bedrck47]

Have you ever cleaned the exhaust ports thru the throttle body. The ports on the 4.6 are noted to clog up Good Video on youtube about cleaning these.

Use some dielectric grease on the contact points of the connectors.
If the connectors aren't holding in place you could use ty-wraps to secure them better

Get the codes and post the numbers