Does throttle body need cleaning?
 

Hello, new to the whole Jeep thing and working on my own vehicles here. Just inherited a 2001 Jeep Cherokee sport with 180,000 miles on it from father. It had a misfire at idle with check engine light that my father drove on for over a year and never bothered to fix. Upon inspecting the air filter, it was one of those K and N filters that was blacker than black and when I spoke with my father, he had only been rinsing it with water and putting it back in every so often (LOL). So this air filter had been in there for well over 5 years.

I replaced the filter, reset the codes, and code hasn't returned in months but the jeep still tends to have a (somewhat) rough idle, and sometimes it does feel like it is misfiring slightly at idle every so often, but hasn't thrown the engine light code yet.

Would I need to clean the throttle body due to the air filter never being changed in years or could this have caused a bigger problem?

You should clean that and the IAC anyway. Well worth the effort if you ask me. I did it to my '00 with about 150K at the time just because. Buy a new throttle body gasket.

What Ralph said.



Why the LOL? That's the correct procedure. It's a permanent filter. It gets cleaned and put back. Some people don't like them, but that's another discussion.

They also make a spray to clean it a little better, and some oil ro put in lightly after...but yeah. Just a rinse and you can use it again and again.

It was one of those 50,000 mile K&N filters that have to be re-oiled with their oil every so often. He was taking it out and just running a water hose through it and putting it back in after it dried, didn't know they had to be oiled. This was done over the course of 150,000 miles and 7 years. When I inspected it, it was completely charcoal black and went straight into the garbage. I thought it was funny he thought it lasted forever because it said "lifetime" filter.

It was in really bad shape with little black specs of something coming off the filter, obviously, it wasn't filtering the air very well and hindering the engine. I was just wondering if this can gunk up the throttle body and cause further issues as described in my original post.

Start with the below procedure. As well as 6 fresh NGK spark plugs properly gapped to .035. Do these two things and then see where you are at. The garbage was the right place for that air filter the way you described it.

Also a good time to review other basic maintenance. What is the history of all fluid changes? Oil, transmission fluid, transfer case fluid, differential grease, and antifreeze. Fluids are the "lifeblood" of your XJ. If in doubt, change them out. Also with the cooling system is a new radiator cap AND inspection of all hoses (they can rot from the inside out and a blown one can leave you with bigger fish to fry). A few things to consider.

You should also research the 0331 cylinder head defect, which came with all 00-01 XJs. There are many threads on this and other XJ forums so no need to reinvent the wheel, a simple search will give you lots of light reading.

With maintenance, "It's pay me now, or pay me a lot more later". You can put that on my gravestone.

Good luck and keep us updated!

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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

Reinstall IAC and check idle quality

Congrats on your new-to-you XJ. Do look into the "0331" head concern and after you get the throttle-body, etc., cleaned, do this:

https://www.cherokeeforum.com/f30/st...-4-0-a-226299/

Helps it purr like a kitten in the top-end. Seriously.

I have read about the 0331 head crack problem, so far I think it mine is good, have been keeping an eye on oil through dipstick and coolant levels. But right now it doesn't get drove much until I can get tranny and diffs fluids changed.

Isn't using fuel cleaner just as effective as this "steam cleaning" the engine method? Something feels very uncomfortable about pouring just water into the throttle body while running. Everything tells me that would be a bad idea, but I'm new to all this and not a mechanic.

As understandably counter-intuitive as this procedure with water seems, it is superior to toxic, volatile chemicals and it's much cheaper. Just don't pour it all in at once. Many of us have followed this procedure with exceptional, proven results. I wouldn't recommend it if I believed it would be harmful to you or the motor.

I was skeptical at first too lol...just do it as mentioned and you will be golden.

Water injection is almost as old as the internal combustion engine. It's tried and proven.

Mallory is just one company that used to make water injection kits for hot rods. It reduces detonation and provides a bit more power, plus it keeps the combustion chamber clean.

It has even been used on commercial jets as a sort of poor man's afterburner. They inject water into the exhaust and get more thrust.

Of course, we aren't using it in exactly that way, and you CAN overdo it, but done carefully, it's a very good thing for your engine.

Here's a thread worth saving regarding water.

https://www.cherokeeforum.com/f30/st...-4-0-a-226299/