I can't seem to find any articles about cleaning the throttle body.
What is the proper way to do it?
Does it need to be removed from they engine?
There is a label on it saying something about not cleaning it.

 

No it doesn't "have to" be removed...but...it does help to remove it to ensure a good job.

I have taken the whole throttle body housing off...(not the intake) Just the housing with the throttle plate and the IAC on the rear or firewall side. I did that because then you can also clean the interior EGR ports that tend to get gunked up over time, and makes it easier to clean or replace the IAC too, as well as, getting a better view of the throttle plate backside. I didn't feel it necessary to take off the throttle plate and just cleaned it on the housing after I removed it from the engine. & that only took a couple hours er so and had it back together.

 

Took a look at mine the other day. It had a black oily coating on the back side of the throttle plate & down into the intake mani. Really wanted to remove TB from engine & clean it really good but the EGR parts looked too rusty to come apart without something breaking . So, I settled for cleaning it as best I could by reaching in with TB cleaner on a rag.
Even though the MAF seemed perfectly clean, I spray it with MAF cleaner since I had it removed. No difference noted afterward.

 

Yep that is the most suspect area is the EGR line. I gave mine a good soaking with some penetrating spray, (let it sit couple hrs or so). Then it cracked open without issue.

It maybe that your EGR tube has a rust hole in it, or rust has flaked off on inside and isn't allowing the EGR associated parts to function properly? Either case ...if the internal EGR ports are plugged inside the throttle body...or the EGR and its components isn't functioning properly, it will give you some runnability issues.

What issues are you having? or just trying to head some off?

 

Just some preventive maintenance things that had never been done. It's running fine. But I have been getting the code (455) for a vacuum leak lately.

 

Code 455 is a large fuel tank leak when a vacuum is attempted to be pulled on the tank.
etc..
The leak is detected when the PCM does a test of that system.
It's not on the engine anywhere.
Good luck.

 

Thank you Bluegrass.

Makes me wonder...what is the reason for vacuum on a fuel tank? Is it an emissions thing? Like to contain the vapors?

 

Fuel tank testing is very complex and long.
It is a federal requirement that vapors do not escape the system.
Vacuum is the only way to test for leaks using sensors on the fuel tank since there is no positive pressure available that would only blow vapors outside through a leak.
The vapors are collected by a Charcoal filled Can then fed to engine vacuum to burn.
It makes it a closed system.
Good luck.
.

 

On the throttle body cleaning, at this late age of the truck don't worry about the tag for not cleaning it.
If accumulations are causing idle issues then it's time to clean.
.
The throttle plate is set by a throttle stop so it does not close fully for two reasons.
1. So the plate does not stick in the bore after the engine cools.
2. It is part of the idle adjustment setup.
Here is how that goes; if the IAC electrical connector is disconnected, there is enough air passing by the throttle plate to allow the engine to idle but at about 500 rpm +\-.
With the IAC connected and operating properly, the PCM can now control the idle at the programmed idle speed of about 650 +\- 50 rpm.
This also affects the cold start performance.
Bottom line is the system is all engineered to perform in a certain way.
This makes idle speed 'non adjustable' from the outside or it upsets the way it is designed to work.
Good luck.

 

Thank you again Bluegrass! I really enjoy all that that technical info!