Why would my idle be high sometimes and then other times it will be normal?

Tiny
RANGERGIRL554
  • MEMBER
  • 2002 FORD RANGER
  • 10,010 MILES
I have a 2002 ford ranger that I ran with a vaccum leak for at leat a year before my husband found it. When he repaired it, he also changed the transmission fluid and filter, and the oil filter and fluid and then cranked it up and ran it for 30 mins and then the idle went sky high to about 3,000 rpms, so he brought it back to the house, and we discovered we had a bad Idle air control valve, so we replaced that, cleaned the throttle body and then disconnected the battery. It drove like a dream for awhile but now sometimes when I come to a stop, it idles up to a higher rpm, and I have to put my foot on the gas to make it drop down. So my husband put dielectric grease on the IAC and connecters, and it didnt do it for about two days after that, but then it started doing it again. I live in louisiana and the humidity is very high here on most days, and it only seems to do it when its humid. Is there something seriously wrong with it, or is it just sticking maybe?
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Tuesday, September 27th, 2011 AT 8:46 PM

6 Replies

Tiny
WRENCHTECH
  • EXPERT
First eliminate all vacuum or air leaks in the system. You may have a bad IAC ( idle air control) but try cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.
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Tuesday, September 27th, 2011 AT 8:48 PM
Tiny
RANGERGIRL554
  • MEMBER
We just put on a new IAC about 2 months ago, could it of went bad already?My husband has checked it over for vacuum leaks and he says he hasn't found any.I know he cleaned the throttle body at the same time he changed the IAC and it idled fine for awhile, but then its like the throttle started sticking, and we would have to push the gas in order to get it back under 1,000 rpms. Now I have to mention that he had put 2 zip ties on the throttle cable to take the slack out of it, before he found out it had a vacuum leak, and kept them on it after he disconnected the battery, now could that of messed up the learning process of the computer while it was learning?
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Tuesday, September 27th, 2011 AT 8:56 PM
Tiny
WRENCHTECH
  • EXPERT
That's possible. The valve body could be worn out causing the throttle plate to bind.
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Tuesday, September 27th, 2011 AT 9:48 PM
Tiny
RANGERGIRL554
  • MEMBER
How would we check that?
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Tuesday, September 27th, 2011 AT 10:11 PM
Tiny
WRENCHTECH
  • EXPERT
Just physically inspect it for wear in the throttle shaft or inside the throttle body where it contacts the throttle plate to the housing.
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Tuesday, September 27th, 2011 AT 10:15 PM
Tiny
RANGERGIRL554
  • MEMBER
I will check that out when he gets home. Now if it was a vacuum leak, wouldn't it do it all the time?
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Tuesday, September 27th, 2011 AT 10:18 PM

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