My 2001 Cherokee was having an issue cutting off at idle so I cleaned my TB today. While I was doing it I went ahead and made a technical post.

Cleaning your Throttle Body (TB) can fix a lot of issues with your jeep, idling high, cutting off at idle or park, it will run smoother and possibly even give you better gas mileage. Also, before you spend all your money on an cold air intake or throttle body spacer(waste) this is a MUST!

So step 1 is having the right tools available. At first I thought that included a 10mm socket, 6" extension and 3/8 drive ratchet to remove the TB from the intake and a T-20 torx to remove the sensors from the TB then just some q-tips, paper towels, carb cleaner and anti-seize. As you will read below I needed a little more. haha

Step 2 is to remove the Intake tube between the TB and the intake box. These clamps are an odd ratchet style but just use a flat head screw driver to pop up the teeth. Do this on both ends and remove the tube.



Step 3 - Unplug all of your sensors from the TB. There are 3 sensors total and you just press the tabs and pull to remove them. One on the front and two on the back.

Next remove the 3 cables on the front of the TB. The two with the black tear shaped caps are removed by pulling in the direction of the cables end. The third cable looks like a metal clamp over a small ball, this cable end simply pops off by pulling away from the ball mount.

Step 4 -Now grab your 10mm socket, a 6" extension and a 3/8 ratchet to remove the 4 bolts holding the TB to the intake.



Once you remove your TB it should look like this....



Like I stated before, the problem with my jeep was it cutting out during idle. The reason for this is because gunk had bound the head of the IAC sensor to the body of the throttle body so while the TB was closed air couldn't flow in the opening you see above that looks like a smiley face.

Step 5 - Remove all the sensors using a T-20 Torx bit. Be very careful, I snapped the head off of a bolt during this operation...



During the removal of the sensors everything went great. It was when I removed the IAC adapter from the side of the TB that I broke the head off a bolt.



The bolt is a T4 so I went to Ace Hardware and grabbed two T4 nuts, I threaded the first nut down to the bottom and then another one on top of that. Then I backed out the bottom nut until it caught on the upper nut and started to remove the bolt. Thankfully it worked.


While I was at Ace Hardware I bought 4 new bolts that had hex heads and were stainless steel instead of the Torx bits that were there originally.



The new bolts had a thicker head but it's ok, they fit.

So now that I have all my sensors off the TB let's look at them.

The IAC (Intake Air Controller) Sensor and the cause to my and every ones problems.



Now what you'll notice about the IAC sensor above is how dirty the copper plunger is on the end. This is the main reason so many people have problems with the idle of their jeeps. This plunger HAS TO BE CLEAN!! If it is dirty is will stick to the body of the TB and will not allow air to flow into the engine at idle.

We'll get back to this a little later.

I don't know what the next two sensors are called but the one with the orange tip senses how open the TB blade is and the other one.. who knows haha. I'm no mechanic.

Sensor2

Sensor3


So put the sensors to the side and let's look at what I am calling the IAC TB adapter (where I broke the bolt). This is bolted directly to the side of the TB and is cast just like the TB. It does have a gasket on it but when I put it back on I just used light dabs of silicon.



When you remove this adapter and I do recommend you remove it even if you do break one of the bolts you will see two passages. See below.



This is how the IAC works. When the blades of the TB are closed like at idle air has to get to the engine somehow so it can idle at a stand still. While the blade is closed the IAC sensors plunger will open slightly to let air into the top opening and into the bottom opening to feed the engine air. If the IAC sensor is dirty it cannot open and let air into the engine at idle so the engine will die out. Hope this explanation helps.

Step 6 - Now that everything is taken off the TB it's time to clean. I started with the IAC adapter and a can of TB / Carb cleaner, q-tips, paper towels and gloves. Soak the adapter heavily and begin to use the q-tips to wear the black carbon build up down. Just keep doing this until the carbon is at a minimum and use the paper towels to try and get off the heavy stuff.




The 2 pictures above are after the cleaning and I wanted to show you the most important part to have clean is where the plunger of the IAC sensor contacts the adapter at the hole you see in the center of the above pic.

Once the adapter is clean carefully take the IAC sensor and with a paper towel with a little bit of carb cleaner on it wipe down the plunger on the top of the sensor until ALL the carbon is removed. Notice below the plunger is shiny again.



Now take the IAC sensor and IAC adapter and fit them together to test the contact patch of the plunger. The sensor should fit into the adapter perfect with no carbon or no spaces. See below.



Notice in the picture above everything is clean and the contact patch between the sensor and the adapter is great. Now we move onto the TB.

Step 7 - Cleaning the overall TB. Let's turn over the TB and see just how dirty 120K miles makes a TB.



There is a TON of carbon buildup in the bottom of the TB so grab a rag and some carb cleaner and use that trusty elbow grease to get rid of it. Just soak and wipe then repeat. You'll probably have to open the blade manually to really get in there and DONT FORGET TO CLEAN THE TOP AND BOTTOM OF THE BLADE. THE ACTUAL BLADE OF THE TB DOOR IS USUALLY WHAT MAKES THEM STICK.

So after scrubbing and scrubbing with carb cleaner and a rag you get this...



It's shiny! Now you want to check anywhere there is carbon and use the carb cleaner and GET RID OF IT! Carbon and dirt build up are EVIL!

Once all the carbon and dirt buildup is gone start re-assembly. First part to put back on is the IAC adapter. I couldn't find a new gasket for this so I went with black silicone... just dab the silicone along the contact patch of the adapter. Keep it very light, you don't want it gobbing up the adapter or TB.



Now just place it on the TB and bolt it back on. Put Anti-Seize on the bolts and just tighten it slightly it's not your suspension so you dont need to put the death grip on it. Just tighten it dont kill it

Now that the IAC adapter is back on it's time to put the sensors back on. These are easy just line them up and put a little Anti-Seize on the bolts then tighten them back up. If your curious the IAC sensor plug should face the drivers side.

So now you should have a clean TB with everything attached back onto it. From here it's kind of self explanatory. Take your TB back to your jeep and before you place on the TB gasket and the TB just check the inside of the intake. See pics below.



If it's not horribly dirty and you don't see anything crazy go ahead and place the TB gasket and TB back on the manifold. Make sure all of your sensor plugs and cables are out of the way then put a little anti-seize on the TB bolts and hand thread the 4 bolts into the manifold. Simply use your ratchet to tighten the TB down but not to tight.

Plug in the 3 sensor cables and re-hook your 3 cables to the TB arm. Clean up and put your tools away congrats, you're done.

This fixed my idle problem. My jeep now idles perfect and can sit in drive forever without dying.

Hope this little tech write up helps. Don't be scared it's honestly one of the easiest things you can do to your jeep besides changing the oil.

-Matt R

PS - Thanks to Brad Birney of Year One for letting me know what was wrong with my jeep so I could try and fix it.

Also, please let me know if anything is wrong. I am no mechanic but I do love this stuff.

 

Talk about great timing...I just posted with an issue on this very part earlier today (below). My TB cables are "very loose" after some work I had done. Are yours snug when you hook them up?

https://www.cherokeeforum.com/f2/acc...24/#post428983

 

I do have an older xj but i had a huge problem with my ccv valve and got oil on the air filter as well as in the intake an you can see it all around the tb on the outside i do believe it is time for a major cleaning.

However she is my DD so how long approx did this take you.?

 

I did this to both my jeeps and they both idle better. On the first one, I snapped off one of those little screws too. Found that when loosening them, if they are snug, alternate between tightening and loosening. Sort of wiggle them and they will come loose. Anti seize is a must for reassembly. The silicone is a great idea! I broke the old gasket on one and re cut one out of stock gasket material. The whole thing took less than 30 minutes (minus the trip to the store for replacement screws).

Great write up!

 

Young Superhero's Jeep is in the driveway. Has to get Mrs Hero to drive him to school. Very embarrassing for the young man.

Printed out the step-by-step. This will be one of those "teachable moments". I get to sit in the chair and teach, while Young Superhero gets his hands dirty. Mrs Hero gets a kick out of these little moments of family "quality time".

Thank you again JCF members.

he he he he he!

 

Great write up! Mine was stuttering a lot during idle, cleaned everything in the TB, runs like a champ! I've even noticed ~1-2 MPG increase.
The worst part were those stupid cable clips. Took me 10 minutes of cursing to get them to come off.

 

I took of my intake pipe for one reason or another and decided to take a gander into the throttle body and low and behold It looks like CRAP you can physically feel the buildup on the blade and the wall.

 

Thank you for the write up! I followed these instructions today and it turned out great!

 

Anyone have new links to the pictures?

 

BUMP... repost with pictures?

 

Very nicely done. Today I cleaned the throttle body, and went ahead and replaced the IAC. I still had the idle problem upon cleaning the TB. So for $70 I fixed the problem. Appreciate the write up! Brad