Keaton

Now let me explain.

Problem 1:

On cold startup in the mornings, when I start driving and its still getting up to full temp, I'll have the heater blastin, with my headlights on and my voltage will read at 9 and my belt will squeak. Until all of a sudden, the voltage will jump up to normal, belt will quiet up and all will be fine. I think it might do this once its at proper temp. Any thoughts? My battery is a couple years old and my alernator is about 1 year old.

Problem 2:

When I'm lettin it warmup in the morning before I leave, it will start fine and idle normal for 2-3 minutes. Then the idle will get wacky. It'll drop down to around 300-400 rpm, then jump up to 1500 rpm, then settle down to 900 again and be alright. Now in the afternoons when I leave work its another story. If I let it sit for a couple minutes it will do the same thing, but if I start it then go right away, it will rev up to 1500 at a stoplight, then idle all rough but when I try to give it gas it will hesitate for a couple seconds. This stops pretty quick when I'm driving but its annoying.

Anyone wanna help? I'm not sure if they are connected, I guess they could be.

Mendax13

for problem 1. just an idea im not all to good with this area but mines a 95 and it draws alot of power because my blower motor is bad/ going bad. something to look into maybe. just a thought.

Modestmike

I had something similar with my xj. The belt would squeal and the idle would drop along with the volts and power steering. I did nothing to the belt and changed the IAC and TPS and haven't had the problem since.

tjwalker

Job #1. Verify the cause of the "squeak". Either it's a marginal belt or something along the route of the belt. Don't rule out the alternator as a root cause as newer alternators fail all the time. In fact, they have one of the highest mortality rates of all aftermarket parts. Below is more on cleaning the throttle body and idle air control. Highly recommended.
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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 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

Reinstall IAC and check idle quality

wjnfirearms

The squeaking of the belt and subsequent low voltage is because the belt is slipping on the pulleys and not spinning the alternator at full speed. It changes voltage when the squeaking stops because it is now catching and spinning the alternator properly. You need a new belt and make sure to adjust it properly.

I'd look at the IAC as an initial cause of your problem. Try cleaning it first as outlined already before you replace it.