Throttle body return spring 1996

I have been dealing with a throttle body issue for months now and I’ve fianally located the issue but not a solution.

My truck idles around 850-900 warm and throttle position is 14.1

I know it should be around 9-10 at idle.

I replaced MY AIC,TPS,MAF,O2 sensors, plugs, wires, fuel filter, air filter, clutch, exhaust, fluids, vsv, dashpot, vac hoses, exc... everything in the pursuit of a solution. I can now see that it’s a mechanical issue, the throttle body linkage or spring return system on my 1996 5vzfe 3.4l v6 isn’t coming all the way back to the set screw when the throttle is released. It’s held slightly up as a base position. I adjusted the idle set screw so that it’s now bottom we out and it still doesn’t get it to position without me physically forcing it there.

If I push It up into the set screw and let go it idles happily at 700.


any ideas any help?

 

Here’s a better illustration of what I need to achieve, the photo is old, before lots of other parts were replaced and the set screw was bottomed.

 

Did you check the throttle body for carbon or for any gap between the butterfly and the throttle body wall.
Should be no gaps.

 

Yea

 

You adjusted the stop bolt, nut for the idle then?

 

My guy, I appreciate you, yes. They are bottomed out as stated in my OP. It’s spring action that is my issue

 

Okok, well try spraying it down with Penetrating oil, maybe the shaft is binding up a little bit somewhere I don’t think I’ve seen a bad spring before.

 

Also lowering the set screw on the top increases idle speed. It reduces it, the stop screw would need to be backed out for the idle to reduce

 

Any suggestions where to look for binding? If I manually return the plate up to the stop it drops the isles to 670-710 but as soon as I step on the gas again it will return to 850 after it returns

 

I’m just thinking out loud to spray down the whole ares on both sides, the spring side in particular.
The shaft would go through the throttlebody and maybe it’s hanging up on the walls of the throttlebody that’s just a guess.
I’m assuming your idle control valve is working correctly

 

Try starting your truck let it warm up to the idle, then go to the engine compartment, grab ahold of the throttle mechanism and pull towards the radiator. Report back if there is any change in the idle, don’t force anything just gently pull the mechanism. I bet you have a similar issue that I had. Over 350,000 miles my butterfly had actually worn into the side of the TB (edit:the butterfly is brass and the TB is aluminum, the TB will wear before the brass) and was holding it up on the firewall side of the TB. So pulling it forward let the butterfly set properly and brought my idle down. I installed a split washer on the shaft to shim the butterfly valve to keep it in the proper position.

I had multiple issues that were compounding into a higher and higher idle. That was one of the things I discovered through a video that I can’t find anymore. I’ve since resolved all the issues and my idle is now perfect

Edit, if this doesn’t make sense I can take a picture showing what I mean

 

When I did this it brought my idle down 200rpm which is exactly where you need to be if you are idling at 900

 

Let me give it a try. I only have 178xxx miles and the butterfly looked to be sealing properly but that sounds similar to my issue


I’ve replaced every other part and sensor basically short of the block and the actual tb in tuning this guy up but this is the last thing that needs solving

 

Before I figured out the shim, I replaced my TB with one from a junkyard that had about 150xxx.
This was because I cleaned my TB and the carbon buildup was holding the air seal. It was really bad on my original TB and my idle shot up to like 3,000 rpm after cleaning.

The one from the junkyard barley had the same issue but it hadn’t worn into the TB more than maybe .001-002, noticeable only with the TB out of the truck and a flashlight looking through. It will always wear into the firewall side of the TB because of the way the thing is made it “pulls” toward the firewall.

The junkyard TB is the one I have in my truck currently and what I Figured out to shim the shaft on the spring mechanism.

Hope this is the issue it’s a very easy fix

 

what do you mean by shim it, can you send a photo?

 

Above photo is the part you need to pull, it’s connected to the Butterfly shaft
Here you can see the wear in my original TB, left side faces the firewall

This is before “pulling towards the radiator”
This is after “pulling towards the radiator”. I hope this helps. You can see how much had worn on mine.
I plan on getting this bored out by maxbore when I can afford to do a supercharger.

 

Sorry I just saw your reply, right where my finger is, is where I put a retaining ring that just happened to fit. That why I save random parts
Retaining rings usually go on the end of a shaft of some kind, and clip on, keeping whatever is on the shaft in place. Like a washer with a portion removed that fits over the shaft. That my best description hahaha.


That keeps the butterfly centered

 

This photo is from a while ago but I didn’t see any gaps in my butterfly when I checked it. I can check again when it’s not raining

 

The best way to test is to have the truck running at wherever it idles when warm.
And just try pulling that part that’s connected to the shaft forward(towards the radiator).

Looking at it while it’s attached to the truck isn’t really going to tell you much, you need to have light behind the butterfly to really tell if there’s a gap. But you will know when you pull on the mechanism if this is your issue because your idle will drop.

The picture you posted doesn’t show the gap, it shows the side that would be worn, which will be tight to the TB.

 

https://youtu.be/IIbTvxR1TQk

Here you go I found it. the truck in the video is a 4Runner, but the same 3.4l engine.
This sounds exactly like what you described. And is how I fixed the last little bit of idle issues on my truck.

Edit: the one difference is where the butterfly shaft is positioned on the 4Runner TB. It is different from the Taco. But the same principle applies, where I point to in that photo is where I found needs to be shimmed on our TBs to solve the issue