Jeep has a low idle... between the first and second line... and lately when I start it... it idles really rough right away until I start driving... what could be the issue?

 

No info on jeep will yield no responses. What year? What engine? Come on now..

 

Ever cleaned your throttle body and IAC?

How long since plugs, wires, cap and rotor?



Courtesy of TJWalker:

--------------------------------------------------------------------
The Idle Air Control (IAC) is mounted on the back of the throttle body. (front for 87-90) The valve controls the idle speed of the engine by controlling the amount of air flowing through the air control passage. It consists of a stepper motor that moves a pintle shaped plunger in and out of the air control passage. When the valve plunger is moved in, the air control passage flows more air which raises the idle speed. When the valve plunger is moved out, the air control passage flows less air which lowers the idle speed. Over time and miles, the IAC can get carboned up which can have an adverse affect on idle quality. Cleaning the IAC may restore proper function and is an easy procedure to perform and good preventive maintenance so it is never a bad idea.

CLEANING THE JEEP 4.0 IDLE AIR CONTROL

Remove the air filter cover, associated hoses and the rubber boot that goes from the air filter cover to the throttle body. Remove the IAC with a torx driver (2 bolts; one can be kind of hard to get to)

"Gently" wiggle out the IAC from the throttle body. Gasket on the IAC can be re-used if it is not damaged

Clean the IAC with a spray can of throttle body cleaner; inexpensive and available at any place that sells auto parts. Throttle body cleaner is recommended rather than carburetor cleaner as it is less harsh, safe for throttle body coatings and is best for this task. Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle that protrudes from the IAC as it is fragile and you could damage it.

Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner

It is also a good idea to clean the entire throttle body itself, the butterfly valve inside of the throttle body and all associated linkage as long as you have things disassembled

 

95 xj with 4.0. Unsure of year...out of a yj. But changed plugs and wires a few months ago... and cap about a year ago... unsure when rotor was changed... but never cleaned throttle body or iac. I did dump some fuel treatment in.. but it didn't fix it. I think motor is a 96??

 

Could be fuel delivery issue caused by bad sensor. Cruiser provided good info. Is cel on? My two Lincoln's is maybe the o2 sensor? But do the cheap/easy stuff first- clean and maybe replace rotor, check plugs for corrosion/deposit, clean up grounds and battery leads and maybe do sea foam thru the manifold via master cylinder vac hose.

 

No cel

 

Clean the throttle body and IAC and then report back.

 

Cleans best if you use your brother in law's tooth brush and some carb cleaner.
Gentle on the IAC pintle cone, brush gently, don't get rammy and damage the internals. Check the vac lines in the area, they can hide some cracks.

 

Iac bolt heads are stripped come to find out... fml. But I cleaned the tb and dumped seafoam thru the manifold.

 

Tb wasn't cleaned the best... but maybe ill take it off someday and clean it thoroughly

 

could also be fuel injectors, try wiggling the plugs ontop of the injectors to see if that helps.