Lazy Idle-Down

[Ifixyawata]

Regarding the Focus in my sig, seems more prominent recently. The car will idle around normal speed, right under 1k. However between shifts (5speed) and after downshifting or otherwise coming to a complete stop, the idle will hang at 2k and very, very slowly drop back down to normal idle. On my way home it took about 20 - 30 seconds to reach normal idle. Downshifting into turns onto a side street, for example, the car feels like it's not slowing down at all on downshift into 2nd.

I suspect a bad IAC, maybe? Could possibly be exacerbated by running the A/C a lot lately.

Anything I can clean or check before I have to spring for a new IAC?

 

[Alex_V]

Check for vacuum leaks and clean the throttle body in general, including the IAC passageway if it's designed with a separate channel for idle flow. If so equipped, remove the IAC valve/motor and clean that cavity and the plunger, too. Then see what shape it's in.

 

[Ifixyawata]

Originally Posted By: Alex_V
Check for vacuum leaks and clean the throttle body in general, including the IAC passageway if it's designed with a separate channel for idle flow. If so equipped, remove the IAC valve/motor and clean that cavity and the plunger, too. Then see what shape it's in.


The throttle body has a sticker on it advising against cleaning it, I think. Something about a coating yadda yadda, not sure if it's really still relevant or what. I do have an aerosol can of specifically throttle body cleaner. Maybe someone with Zetec experience will chime in regarding that.

I will look around for a vacuum leak though the idle does, eventually return to normal. Will move forward with cleaning IAC, though I've heard it's a bear to get to.

 

[Alex_V]

I did it on an '09 with, IIRC, the same warning. I forget how I did it, but I know I used some sort of cleaner and I just had it in tue shop again Saturday, a year later, and it's running like a top.

 

[Colt45ws]

I cleaned the TB on a '05 F150 and it fixed a bunch of issues. It could not idle above about 400 rpm for anything until I cleaned it.

 

[Linctex]

Originally Posted By: Ifixyawata
Focus ...between shifts (5speed) ... the idle will hang at 2k and very, very slowly drop back down to normal idle.


I thought all manual trans Fords did this.
My '91 Mustang 5.0 did it, so did my friend's '96 F150 with a 300 6cyl.

It was programmed into the computer.

 

[Ifixyawata]

Originally Posted By: Linctex
Originally Posted By: Ifixyawata
Focus ...between shifts (5speed) ... the idle will hang at 2k and very, very slowly drop back down to normal idle.


I thought all manual trans Fords did this.
My '91 Mustang 5.0 did it, so did my friend's '96 F150 with a 300 6cyl.

It was programmed into the computer.


That idle hang usually drops off much quicker than what's happening now, I think. The RPMs actually climb in some cases right now.

I will clean the TB and IAC during my next OCI and hopefully that will show some improvement.

 

[E150GT]

Originally Posted By: Linctex
Originally Posted By: Ifixyawata
Focus ...between shifts (5speed) ... the idle will hang at 2k and very, very slowly drop back down to normal idle.


I thought all manual trans Fords did this.
My '91 Mustang 5.0 did it, so did my friend's '96 F150 with a 300 6cyl.

It was programmed into the computer.


The only time mine has done this is when I messed with that little screw on the TB. I had to take a socket and ratchet and drive down the street stopping to adjust it every few hundred feet to get that sticky throttle to stop.

 

[SwampSurvivor]

With the exception of the 2.0L ecoboost my parents have now, that's been normal behavior for all of our Fords. My 2011 Focus will race along at 2500 on cold mornings. Same with the F350. And my old Taurus was the same, though it was an automatic. I could start the taurus up and put it in gear and it would accelerate up to 30 or 35 on its own.

Racing when cold is a Ford thing. Some toyotas do it too.

 

[JamesBond]

I have a 97 escort that was doing something similar(different engine and automatic). Cleaning the tb icv and pcv with throttle body cleaner (it said it is safe for coated tb's) did nothing. A new $2 purolator pcv valve made an immediate improvement, next time I will buy a motorcraft pcv but for now this one is much better.

 

[01rangerxl]

Originally Posted By: Ifixyawata

The throttle body has a sticker on it advising against cleaning it, I think. Something about a coating yadda yadda, not sure if it's really still relevant or what. I do have an aerosol can of specifically throttle body cleaner. Maybe someone with Zetec experience will chime in regarding that.


Throttle body cleaner (not carb cleaner) is supposed to be safe for the coating. At least CRC's offering says it is. I have used it on my Rangers with the same sticker without any issues.