Why clean throttle body?

[drallan]

Ok, probably a dumb question here. I've got an 04 V8 4wd, but I don't really think that it matters (this applies to all cars/trucks). This past weekend I was replacing the tensioner pulley and had to remove the air intake tube, while doing so I thought to myself "I should clean the throttle body while I have it off". So I took out my trusty old spray and cleaned her out as best I could. Afterwards I was thinking to myself, "why do we do that?". I've always cleaned out the throttle bodies on various cars. And I know it is supposed to help, but how does it really?

Typically you get some of the gunk and varnish off the butterfly and parts you can see, but does that really do anything? The MAF is way before the throttle body (I know cleaning that helps), but unless you have a stickly throttle plate, how does cleaning it really do anything? There can't be but a thin coat of dirt on the intake which I can't see changing the volume or airflow that much to warrant a significant difference. Usually the springs and cables have plenty of tension to open/close the plate. Maybe spraying gets some things further down in the intake cleaned up a bit or cleans up other sensors (IAC, MAP). But other than making me feel like I did something, what real good does spraying and wiping around the throttle plate really do?

 

[zonianbrat]

I had a sticky throttle on a previous SUV. Cleaned the throttle body and it went away. Got a lot of gunk out of it when I did it. The fuel had varnished in there making the butterfly a bit sticky.

 

[sprocketus]

If the throttle plate is being held open by carbon build up (or anything else), you will have a rough idle. Cleaning it up will make sure that it will rest in the correct position at idle.

 

[YorkParts]

Yea I would just think of it as clearing up any gunk so it can move freely and not cause and little issues.

 

[DMX512]

Do you guys clean it in place or remove, clean and replace?

 

[V8PoWer]

I cleaned the throttle body a while back. Wiped off the black gunk where the throttle plate was resting on. Battery was disconnected to reset the ecu. Up to today the idle was never the same again. Even with multiple ecu reset it Idles high and even higher with ac kicking on.

 

[t-rex grrr]

Do you guys clean it in place or remove, clean and replace?

I've cleaned it once and removed it to clean both the front and back.

Mileage at cleaning: 91k

Front Before

Front After

Rear Before - It's a little hard to tell, but the inside rim was filthy and it took a while to really get all of the gunk off.

Rear After - Big difference

 

[BlackWorksInc]

On modern electronically controlled throttle bodies, there is no "IAC" (Idle Air Control) Valve. The way idle is maintained is by the ECM making slight adjustments of the throttle blade until a stable idle is achieved, at which point the ECM records that value and it becomes base idle. Where as in an IAC vehicle there's a bypass port that is controlled by a separate actuator that lets enough air bypass a closed throttle plate to keep the engine running.

Now then, over time gunk builds up and the ECM may adjust for that to a degree; then you go to disconnect the battery to do some work. After you start the vehicle up again it may just stall out, idle poorly, or just run like crap. The reason is because the difference from actual throttle plate closed and the learned idle value has become significantly different that the ECM can barely keep the vehicle running because what it thinks should give stable idle is actually choked off by gunk.

This is the main reason behind typical concerns such as "I changed out the battery and/or had it disconnected and now my vehicle won't idle/stay running/stalls out/ect." Cleaning the throttle body prior to reconnecting the battery (Never manipulate the throttle body with the key on, doing so can damage the TPS and/or throttle body motor) will give the ECM a clean slate to start idle adjustment from.

On top of all that, carbon build-up can cause turbulence and air current to change slightly when at partial throttle and thus create a slight choking effect due to "eddies" in the air stream. It's a minor thing and most systems will adjust for it well enough, but it does bring down efficiency some.

 

[OnTap]

Great reminder to do this!

Going to add it to my list of winter maintenance for my 4Runner!

Thanks!

 

[sprocketus]

Thank you Blackworksinc for the great tech post. One of the issues with buildup on the throttle plate that I experienced, was it would stick and not accelerate off idle smoothly. Cleaning the buildup with carb cleaner resolved that problem.

 

[Rich G]

I am having an issue where the car occasionally won’t accelerate when pushing the pedal but everything seems like its running fine.. if I restart the car it works normal. This is an 03. Is that a similar problem?

 

[impervious17]

I cleaned my throttle body today after 263k miles. BOY the engine runs so smoothly now. It idles better than before. Not sure if its saved MPG or worse.

 

[rwh963]

having possible issues myself (230k miles). want to give this try. why disconnect the battery? and if so, dismount the body, clean, remount, then hook up battery?

 

[Keros]

I am having an issue where the car occasionally won’t accelerate when pushing the pedal but everything seems like its running fine.. if I restart the car it works normal. This is an 03. Is that a similar problem?

I realize this post is years old, but I had this issue happen over and over. Techs couldn't figure it out because my description of the above and the truck running normally in their shop, was useless. There was no way to reliably reproduce the problem and the truck did not throw a code when it happened... so they had nothing to diagnose, nothing to work with, other than just guessing and throwing parts at it.

Replacing the throttle body fixed this problem.

Hopefully this helps others who suffer this malady who may happen by.

 

[rdruss]

Watched the 'Car Care Guy" recently, who is a Toyota mechanic and he performed a TB cleaning with rag and TB cleaner and explained the benefits. I decide to clean mine, an '03 V8 and it had a heavy black, greasy deposit.
It may not do a whole lot, but I feel better and that matters.

 

[rwh963]

that's the throttle bod in the center of the pic, correct? have to completely disconnect it. the MAF sensor is to the left? any other things out there need cleaning?

 

[Bluesky 07]

Yes, that's it. Do not over tighten the bolts that hold it on. I broke one off once and was very fortunate that the remnant protruded just far enough for me to get a pair of channel locks on it so I could back it out.