High idle RPMs?

HOOKIE

MEMBER
1998 KIA SPORTAGE
2.0L
4 CYL
2WD
AUTOMATIC
150,000 MILES

Hello, one day I started the car and it revs up to 3,000 RPMS! Only at cold start when I shift it went away so I ordered an OEM Air idle control motor and a throttle body valve. Now the RPMs are about 1,300 I backed out the idle screw all the way and it still revs high. When I turn the A/C on, it idles lower by about 500 RPMs, weird. Please advise. I can't adjust the idle screw any further to make the idle speed lower with both new parts it still idles high when warm at about 1100 RPM any advice appreciated I did not clean throttle body. Lots of work in taking it off.

7 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,690 POSTS

I would put the idle screw back where is started. The high idle can be caused by an intake vacuum leak, please go over this guide:

https://www.2carpros.com/articles/engine-idles-too-high

Also remove the throttle cable from the throttle body to see if the idle is lower. Also let's run the codes to see if any are stored.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please upload videos in your response of any problems so we can see what to help you with.

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Wednesday, June 5th, 2024 AT 5:02 PM

HOOKIE

MEMBER
79 POSTS

Hi Ken,

thank you for your reply. Now the car idles at around 900 RPMs. I put in a new idler air control and a throttle positioner sensor in the car.

Before I replaced both, the car (at cold start) would first idle at 3,000 RPMs when cold started I unhooked the IAC valve and it seemed the culprit.

Although I replaced both and reset both and still can't get rpms to get to 750 RPMs as needed for car specs. Removed throttle cable and it did nothing to the idle. I unhooked it but didn't step on the gas, is that what you wanted me to do?

Also, when I turn the A/C on, the idle doesn't increase a bit like it used to. It actually lowers a bit?

I don't see any air leaks, although I didn't check my PCV valve doesn't the valve cover has to come off to replace the PCV valve in a 1998 kia Sportage? Please reply. Thank you

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Thursday, June 6th, 2024 AT 7:39 AM

KEN L

MASTER CERTIFIED MECHANIC
47,690 POSTS

I wanted to make sure the throttle cable was not holding the throttle bore open causing the high idle problem. So now we can remove that from the equation. To see if the PCV valve to the problem when the engine is running pinch off the vacuum hose to see if the idle changes. Also, let's check the EVAP purge valve to make sure it is not stuck open and here is the location of the PCV valve. Also, the EGR valve could be stuck open which is in the image as well, so remove it and follow this video for testing.

https://youtu.be/DqUCbbKdWf4?si=3cL8BaDcb-rEPv90

Check out the images (below). Let us know what you find.

Images (Click to make bigger)

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Thursday, June 6th, 2024 AT 4:07 PM

HOOKIE

MEMBER
79 POSTS

Hello, I don't have an EGR valve as pictures and my evap purge valve is brand new. So that should rule it out its so hot here in Florida that it is difficult to work on car, but it still idles much better since the new idle air control valve and new throttle body. I'll check the PCV valve. Do you know if 1998 Kia Sportage valve cover has to be removed to replace the PCV valve?
Thanks, Ken, for all your help, Gail

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Friday, June 7th, 2024 AT 7:37 AM

KEN L