Annoyingly High Idle

You still have nothing to lose by cleaning it. You aren’t really making the problem worse - the problem is still the same. Dirt isn’t a proper fix to a problem. High idle can be caused by other things not related to the TB as well.

 

Yes like the thermostat being stuck open is another possibility. I had 3 different things all lending to a high idle. Required fixing all to get back to spec.

BUT, if you have the wear issue In the Tb like I had, I’m telling you, until you have a fix, don’t clean the carbon buildup around the butterfly, it acts as a seal. When you remove that seal, more airs gets by and the computer has to deal with the excess air somehow, and it matches the rpms to where they should be based on how much air is entering the system.

 

this makes sense. I’ll inspect it and see how it looks then go from there. If there’s wear I’ll end up getting a new one.

 

Let's clarify the difference between symptom and problem. High idle is a symptom, not a problem in itself. The problem in your case was a failure to seal in the throttle body butterfly valve. The problem doesn't change when you clean the carbon buildup, the symptoms do. The problem is the same. Unless you break something while cleaning, you will not make the problem worse in any of these cases. FWIW I imagine most guys won't know if the butterfly valve is out of spec if they don't clean it, considering if they were skilled enough to recognize that prior to cleaning, they wouldn't have searched on this site for info.

 

I ended up with a junkyard TB with a similar but less significant issue than mine. I solved it by placing a shim washer on the shaft to center the butterfly valve. You might be able to do that

 

okay, that’s fair. So I’ll say, cleaning the carbon buildup will expose the problem more, leading to worse symptoms of the problem.
I’m not sure how semantics changes the reality that the rpms will go up IF wear is the issue and you clean the carbon seal away.

I agree, most people wouldn’t have any idea that was the issue until they cleaned it. In all honesty, I didnt know, and I ended up making my symptoms worse to the point where I was idling up past 3000. (When the real problem was my Tstat stuck open, if I would have just fixed that Tstat and radiator, I wouldnt have had to go get a new TB for a long while)

and that’s why people like us who have already done these things and learned, can help other people avoid making their symptoms worse during the diagnosis period. At least if they need To be driving the truck while diagnosing like I have to do.

 

I believe auto trans has a different part number for the throttle body, The TPS/IAC interact with the auto differently. Just be sure to input your VIN on the site and it'll help you choose the correct part number.

 

Besides having a little noisier engine sound at stop signs, the difference between a high idle at 1300 and 3000 doesn't really do much - you still need to fix your truck and won't hurt anything - nothing's going past the engine's capable operating conditions.

 

So I decided to take it off and clean everything. I included a picture of it clean and yes the carbon was keeping a tight seal and now you see it has light coming through all clean. And yes it did Idle at slightly higher RPMs now.

I’m guessing now the best way to fix this is just get a brand new one.

 

You could send it out if you don't need your truck any time soon.

 

Yea I could. It’s not my daily driver. Just debating between that and a new one because the new one comes with a new IAC as well.

 

There’s a diag for making sure your IAC works here - I went through it in this link. I used a $7 Harbor Freight multimeter and some T pins from Walmart for $3 for a cheap way to backprobe.

https://www.walmart.com/ip/Dritz-T-Pins-40-Count/48647573

https://www.tacomaworld.com/threads...upercharger-install-diagnosis-3-4-5vz.616967/

Also I’d bypass the throttle body coolant line since you’ll be possibly removing it a few times if you diagnose the IAC.

Here’s a guide to back probing a connector

https://youtu.be/Spy8AXlxVT0

 

Thanks I’ll check it out. I also noticed that after my second startup within a short period of time after I shut the truck off, the truck idles where it should be under 1000rpms. Not sure why it does that.

 

Just wanted to say I bought the new TB from Toyota parts deal and now the truck runs how it should. Idles under 1000 rpm now like it should.

 

I am reviving this thread as I am having the same issue. My throttle body is worn and when I cleaned it it got worse. I put another TB on which looks better but I have worse results (Higher idle). I want to make sure it is not something else before I spend $400. I do have an aftermarket maf. Thanks in advance for ideas.

 

http://maxbore.com/

 

What are your maf readings and throttle position at idle?

 

What RPMs are you at?

 

I am familiar with Maxbore, definetly an option.
I do not have a scanner that can read live data.
Idle in park is 1500+-
In drive 1000

 

This has been my setup for a bit - with a $10 phone app. There’s better out there, but been doing what I’ve needed.

$22 Foseal OBD2 Scanner, WiFi Car Code Reader Check Engine Light Diagnostic Scan Tool for iOS and Android

https://www.amazon.com/Foseal-Improved-Version-Diagnostic-inCarDoc/dp/B077F8F6TB