I was wondering if a vacuum leak would cause the idle to be higher than usual. Right now the idle screw on the motor fully closed and when the truck is warm it idles anywhere from 1200-1600 rpms. When the truck is cold it will idle like it should when its warm(750-1100), and when warm it will idle like it should when its cold(1400+). It still acts the same when in 4wd. It started doing this about a week ago, since then it stopped for a couple days after I took off the throttle body and cleaned it. Then one night when I was driving home it started again. The wierd thing is both times it has happened, I was driving at night, at fairly high speeds (65-70mph). . My best guess to what is going on would be a leak somewhere in the throttle body that is letting air past the butterfly vavle. If anyone has a clue to what is going on, please help me. Im almost ready to take it to a mechanic .

Also, I have check the TPS and its ok.

 

Yes, if you can't get your idle down, 99% of the time it is from a vacume leak. I had that problem and it ended up being a worn thottle body. Grab the linkage and see if if has any play.

 

You bet, vacuum leaking "out" of the intake = air leaking "into" the intake. Doesn't matter if the air goes by the butterfly valve or around it (via a leak), air is air. Besides hoses, check things like the fuel injectors, EGR valve, etc. They can all let air in.

Check your TPS, make sure it is adjusted properly as well.

 

No play in the linkage, Im going to try and cover up some of the ports in the T.B. and see if I can pin-point the source of the leak. I have swapped out a different TPS and its had no effect. Also the idle is rougher than usual too.

 

If the idle is rough then it could be a worn out air flow meter also. have any firiends with Toyotas that you can swap over the air flow meter and see if it changes?

 

I have a friend with an 85 pickup. Do older 22re's have the same AFM?

 

i had the same sort of problem for awhile, i went off-roading and when i was done for the day my idle was REALLY high, and i was like "wtf?" looked at the little thing (sorry im a mechanic idiot, when it comes to names of things) that you can pull for your throttle to rev the engine from the engine bay(on the side of the intake plenunum), and it worked fine when reving and if i let it go it would go back to high idle when i pushed it down to slow down the idle there was a little stopper that was keeping it from going any farther down i examined it and it had a spring on it, and a plastic cover that was torn, i figured it was just worn out i took a hammer and pounded it down, and the idle returned to normal....3 months(2 weeks ago) later same thing happened, used a hammer returned it to where it should be, but it kepts going back. looked at it a little closer and there wernt any wires attached to it, no hoses..just 1 screw, holding it on...so i took it off. I think what it is, is like an automatic choke of some sort that is activated via temp outside/engine temp. at any rate removed it and now my idle is normal the way it should be. Only thing that changed, is when i let my foot off the gas it drops the idle A LOT faster than it did before.


I know that thats one big ramble...and that it prolly makes no sense, but your problem sounds like the problem i had. I will try to post some pics of it tomarrow, and maybe that will make all of what i said come together.

 

No, I don't think so. I tired using one off a first gen pickup when my idle was messed up and it got even faster.

 

What that "thing" does is prevents the throttle from closing with a snap, lets it down a bit more slowly. Helpful for emmissions and makes it shift better on the highway too. The engine can even backfire sometimes without it. Sounds like yours just got worn out.

Generally there is no problem removing it - some people remove them deliberately, but I like it there and would replace it.

 

That part is called the dashpot. Works as decribed above, essentiall a shock absorber for the throttle. Common problems are the little air filter below it gets clogged and that slows down the rate of closing. Or the plunger itself gets sticky, some spray silicone will free it up. I keep mine installed, and adjust it so that it only depresses about 1/2 of it's stroke. The little spring tension in it helps lift the throttle off idle smoother, without it there I find my throttle kind of sticks a little. I still have the more complicated early 22RE throttle linkage and it does not have an efficient pull on the throttle at idle.

 

I think i have figured out what is causing the problem. Today i tried putting tape over some of the little ports inside the throttle body. Sure enough when I covered the large port slightly to the left on the bottom of the T.B. the idle was back to normal. So now I have to find out what that port does and how I can fix it. Anyone have any ideas?
Thanks

 

That is probably the cold idle aux. air valve connection port, at least on the early style throttle bodies. Air valve is supposed to be open when the coolant is cold (to boost the idle speed and warm the engine up faster) and then close when it gets hot.

 

Can you post a pic of the port?

 

I was referring to the large port shown on the lower left side of my early-model TB:

 

Ill get a pic up tomorrow. If you look directly into the throttle body, infront of the butterfly vavle, on the bottom of the body is a hole a bit smaller than a dime. That is the one i covered.

 

I believe Roger is correct. On the later style t-bodies, the aux air valve is built into the t-body itself.