1992 spuddering in warmer weather at idle.

My 1992 XJ Larado will somtimes spudder and die at idle in warm or hot weather, but this winter I have not had any problems. The other day it was a little warmer out and the same thing happens. Sometimes I have to give it gas while braking at a stop sign or just when I have to slow down and havde to let off the gas.

I did a little searching on the forums at found a few that relate but not with the weather part.

I am new to jeppin and hope this forum will guide me in the right direction.

Thanks for your help!

1. Be sure tuneup hardware is fresh. Plugs, wires, cap, rotor, fuel filter, air filter

2. Be sure battery is up to snuff. LOAD TESTING is the only conclusive way of determining battery condition.

3. Assuming no check engine light? If so, pull codes for guidance

3. Testing of two things should be considered. Fuel pressure (with a gauge) at the schrader valve on the fuel rail, compare your readings to factory spec. Also testing of your throttle position sensor

Is the idle too low. Cleaning of the IAC may pay off.

winterbeater said:

Cleaning of the IAC may pay off.

Click to expand...

Good idea. Cleaning throttle body/IAC never a bad idea.

The Idle Air Control (IAC) is mounted on the back of the throttle body. 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.

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

Reinstall IAC and check idle quality
　

I was on a trail ride over the weekend & the jeeps were idling for a long time & a few of them were running like that. One guy we were with was saying it is attributed to "heat soak" & the fuel burning off a little bit before it detonates. May or may not be true or relavant.

Hey thanks a lot everyone! That is just the info I need. I will try these ideas this weekend and see how it goes.

Thanks for all of your help!!