Rough idle after 2 minutes it will come down to 1100rpm?

Tiny
RWALBROEHL
  • MEMBER
  • 2006 TOYOTA COROLLA
  • 1.8L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 79,000 MILES
When starting car initial idle is like 1600rpm. After 2 minutes it will come down to 1100rpm.I put it in reverse car seem to run rough. Going forward after warming up and at a light it idles down to 700rpm. Seems to run not as smooth when its was new. My car does not have a throttle cable but is electronic. I can't see this IAC valve that they show on cars with cable control. I did clean the map sensor before and also cleaned the throttle body butterfly on the front side only as I didn't remove it. Is there anything else in that area that need spraying. I used the proper map cleaner and throttle body cleaner. There are no engine codes. So was wondering this design does not have a removable IAC that can be cleaned because I don't see one. Any ideas what to do next. I also changed plugs with new ones. Vacuum lines don't have any cracks. Did a relearn on the idle with key in key off and back on etc. No help.
Thanks
Bob
Sunday, March 1st, 2026 AT 12:30 PM

1 Reply

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 55,018 POSTS
Hi Bob,

Yep this car dos not have an IAC, the throttle body handles all of that. Chances are the throttle body will need to be replaced or you have a sizable vacuum leak. Here is a video for you to help find a vacuum leak, also we should runt he codes to see if any are stored. These two videos will help.

https://www.youtube.com/watch?v=LRKWV4Are5c

and

https://www.youtube.com/watch?v=LBCpCWEFnTg

Please upload a short video in your response of the problem, so I can see what's going on. Ken

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Monday, March 2nd, 2026 AT 9:18 AM

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