'91 YJ idle problem

[Ray VanBuren]

Wont idle but instead, it races to an extremely high rpm. Troubleshot via Haynes manual(worthless), replaced TPS switch, and still no change. I'm stumped. Anyone out there know what it could be? BTW, it's a 2.5 4 cyl.

[mycj7]

Check for vacumn leaks?

[Ray VanBuren]

Check for vacumn leaks?No vac leaks.

[kloppk]

Possibly a stuck IAC.
Try pulling and cleaning the IAC.

Is the throttle plate closing properly?

[Ray VanBuren]

Possibly a stuck IAC.
Try pulling and cleaning the IAC.

Is the throttle plate closing properly?Throttle plate fully closed. What's a IAC?

[pschneider]

are you sure you don't have a vaccume leaks. My 95 with the 2.5 was idling a little high about 1500 then one day it started idling about 3000 I had to change my intake gasket. I would almost bet you have the same problem, I tryed all the spray it with carb cleaner tricks but the leak was so bad that it had no affect on the idle. The IAC motor is the thing on the side of the throttle body that sticks out about and inch or so, is held on by 2 bolts and has either 3 or 4 wires (I don't remember off hand how many)

[Ray VanBuren]

are you sure you don't have a vaccume leaks. My 95 with the 2.5 was idling a little high about 1500 then one day it started idling about 3000 I had to change my intake gasket. I would almost bet you have the same problem, I tryed all the spray it with carb cleaner tricks but the leak was so bad that it had no affect on the idle. The IAC motor is the thing on the side of the throttle body that sticks out about and inch or so, is held on by 2 bolts and has either 3 or 4 wires (I don't remember off hand how many)I'm sure on the vacuum leak. I'll check the IAC.

[mycj7]

Also check the MAT sensor (Manifold Air Temperature), if that is bad you will have idle issues.

[Ray VanBuren]

Replaced IAC. No change.

[butch6924]

Pull your codes. A lot of people start throwing parts at the symptoms. The problem might be a lot harder to find. You can pull the codes yourself and then find the translation in your haynes manual. FYI, even if the check engine light isn't on, there may still be codes.

[Ray VanBuren]

Found problem. Three bolts missing from intake/exhaust manifold. Replaced bolts and gasket. All better.

[pschneider]

Found problem. Three bolts missing from intake/exhaust manifold. Replaced bolts and gasket. All better.
Today 12:22 PM

are you sure you don't have a vaccume leaks. My 95 with the 2.5 was idling a little high about 1500 then one day it started idling about 3000 I had to change my intake gasket. I would almost bet you have the same problem, I tryed all the spray it with carb cleaner tricks but the leak was so bad that it had no affect on the idle.

Isn't that what said you had a serious vaccume leak at the intake.

Just a warning you are going to need to replace the intake gasket shortly I though I had mine fixed by putting new bolts in but after a while it got worse than it ever was and I had to replace the gasket.

[Ray VanBuren]

Isn't that what said you had a serious vaccume leak at the intake.

Just a warning you are going to need to replace the intake gasket shortly I though I had mine fixed by putting new bolts in but after a while it got worse than it ever was and I had to replace the gasket.

Yeah, I know. I did replace the gasket along with the bolts.

[pschneider]

i know when I pulled mine of and looked at it I could see where it had been sucking air on the rear two cylender but mostly the rear. If I remember right mine was missing 2 bolts.

[Ray VanBuren]

i know when I pulled mine of and looked at it I could see where it had been sucking air on the rear two cylender but mostly the rear. If I remember right mine was missing 2 bolts.
Mine were missing in the rear also.