When I start my Jeep on these cold mornings it seems to idle really low (500 rpms?). If it idles a little higher (around 8-900) it will sometimes drop down and bounce up and it's kind of annoying when I hear it warming up and I keep thinking it's going to die. Got any ideas to fix/help it? Maybe it's just that I'm new to Jeeps?

 

i would pull your air filter and give a look over, if it's dirty, replace it. Also, run some MAF cleaner and throttle body cleaner through. Next, try something like Seafoam or Marvel Mystery oil through your fuel system. Have you looked at your spark plugs lately? Might be as simple as an easy tune up...

 

Yea well I just looked again and it's idling more at 200-300.....NASTY. Just changed the oil and put Seafoam in my vacuum line and gas tank 2 weeks ago. Just bought new plugs, air filter, and fuel filter a couple minutes ago. The air filter was pretty icky. It's almost like there was engine oil in it?

 

ya the oil in/on your air filter is called blow-by. Excess crank case pressure gets re-routed back into your intake system which can and will include bits of oil. research 'catch can'. I used a generator oil/water seperator on my YJ to catch the oil, then i let the excess pressure go back into the intake system. most people just put a breather on top of the valve cover, but i have a sticky ring and it's causing a lot of excess pressure, so i wanted a vacuum to help it out some.

you did good getting plugs and the filters. i still highly recommend cleaning out your throttle body and MAF....it will do wonders. That oil you were talking about in the air filter also builds up inside the throttle body....i would be willing to bet that this is the majority of your rough/low idle problem.

 

On a 1990 you may have a Renix emissions system- they're notorious for having faulty idles due to bad grounds(-). Clean your negative battery terminal, the connection it has to the engine block, and the connection from the engine block to the firewall (braided wire above the valve cover). Below the dipstick is another place where the grounds bolt up, so clean that as well and use some dilectric grease on your connections.

 

You are wonderful What cleaners do you recommend to clean out the throttle body and MAF? And also what is MAF?

 

Splendid idea mate.

 

http://en.wikipedia.org/wiki/Mass_flow_sensor
Measures how much air the engine is getting.

http://shop.advanceautoparts.com/web...2_T%7CGRP2030C_____

 

I love this forum so much it makes me want to cry

 

i know there was a link, but in normal people terms, a MAF is a Mass Airflow sensor. It tells your computer exactly how much air is coming through the filter and into the motor. The reason that's important is because then the computer can add exactly the right amount fuel to match the air....otherwise known as your air-to-fuel ratio. If this sensor is dirty, fouled, or broken, it throws off your air to fuel ratio which is what your engine depends on to run correctly. Too much air, not enough air, too much fuel, and not enough fuel makes your engine do lots of crazy not good things. so....keep your MAF clean.

Also, just stop by autozone and pick up a bottle of 'MAF Cleaner' and 'Throttle Body Cleaner'...it doesn't REALLY matter what brand, just get autozone's brand, it will do fine. i would pick up another bottle of Seafoam and fill up your gas tank, and put the seafoam in it. It will scrub down your injectors and fuel rails. This is good.

 

Okay and where exactly is the MAF located if it's easy to explain.

 

scratch that..........you have a MAP (Manifold Absolute Pressure) not a MAF. My bad... i just got my cherokee and my YJ is carbureted....and from the looks of the location, you probably don't need to clean it out. just go get a big bottle of throttle body cleaner.

 

Oh okay thanks that'll definitely save me some time..

 

when cleaning out the TB, take of the intake hose from the throttle body which will expose the butterfly. If that's SUPER dirty, spray some of the cleaner on a rag and scrub it off. then start up your Jeep and manually hold open the throttle to about 2k RPM and start spraying down the throttle body. your motor is going to want to die, but keep up the RPM and do short bursts (about 2-3 seconds). don't spray too much and don't let your motor die, cuz it might be a pain getting it started for a few seconds. you will probably see smoke come out of the tail pipe...don't worry it's ok. i would do at least half of the can. at least. maybe even the whole can. Make sure to spray all inside there, not just one spot.

 

I love all of the knowledge that flows from your brain down to your fingers which then type it out in a beautiful flood of information that then saturates my brain. Thanks beef.