For the last few weeks I was having an issue with my '89 4Runner V6 where the idle would randomly go high at idle. This is either in park or in gear. It would idle at 1200 to 1300 RPM in park, 900 or so in gear. Then, if I drove it a few miles and stopped again, it might or might not do it again, totally random.

I checked the TPS too many times, swapped it for my spare, not that. Checked the linkage, adjusted the throttle stop, cleaned up the little diaphragm / pot, checked the timing, checked the AFM, searched high and low for vacuum leaks. Nothing. If it was doing the high idle deal, I could not set the idle RPM correctly, even with the idle screw all the way in.

Last week I read a thread where a guy found an issue with the coolant temperature controlled idle air bypass circuit. In the bottom of the throttle body there is a spring loaded plunger that is awash with coolant on one end and has an idle air valve on the other end. When the rig is cold, that circuit is fully open and allows more air to bypass at idle. When the rig warms up, it is supposed to close (not sure if it closes all the way, or just restricts airflow to a consistent amount).

So, today I tore off the throttle body and found out that the coolant passageways where clogged full of gunk, I could not get any water through there in my sink. I hit it with the air compressor and pushed out a ball of crap that had built up in there. I rinsed it out really good and bolted it back on.

Solved the problem. I hope this helps someone down the road.

Mike

 

Nice find!

Can anyone tell me if the 22RE has this???

I'll try anything at this point to fix the damn idle...

 

Yea thats a very common problem , congrats on fixing it !!

 

What part of the throttle body was this? can you post a pick or something? thanks

 

Sorry, it is bolted back together, and you cannot see it very well with all the plumbing on it.

On the bottom of the throttle body, towards the "back" (where it bolts to the intake plenum) on the forward side and towards the "front" on the rearwards side there are two coolant hoses attaching to the throttle body. One is in, one is out. I'm not sure if coolant flows through there when the thermostat is closed, but, when it is open coolant is supposed to flow through the throttle body.

On the rear side (right as you look at it from the driver's side of the rig) is a small plate with 4x M4 screws. Under that plate you will find a passageway from in front of the throttle plate to behind the throttle plate. In this passage is a plunger that, when cold, is pulled back and let's air flow through there pretty easily. When the coolant heats up, the plunger is pushed out and it blocks airflow. I did not see a seat, like a valve. I think the plunger moves into the opening and restricts airflow to an amount that the computer takes into account.

Anyway, below is a picture from my FSM. You can see one of the coolant tubes just below the TPS on the right side of the picture. Also, there is a cutaway of this idle air valve on the right.

[IMG][/IMG]

When taking off the throttle body, remove the vacuum lines, throttle/trans kickdown cables, and the large inlet tube. Unbolt the TB and move it out and up. You can then get good access to the coolant hose trention clips, move them back, and remove the flex lines.

I replaced the 4x M4 screws on the cover plate with cap head M4's, as the philips head screws where rolling out on me. I did not have a new gasket, so, I used RTV.

Also, you have to drain the coolant down a gallon or so. I just drained it all and replaced it as a maintenance item.

You might want to pick up a new TB gasket before doing this. They tend to rip and tear apart when you remove the TB.


Good luck,

Mike

 

Well,

As luck would have it, I do have a couple of pics from my rebuild. Posted below.

In the first one you can see the plate where the valve is located. The others show the coolant hoses that attach to the throttle body.

[IMG][/IMG]



[IMG][/IMG]

 

Ok. I was thinking of taking that off when I was messing with my tps but didn't. I probably should tho because there was a lot of gunk in my coolining syatem and I wouldn't be surprised if it was clogged.

 

Ok I'm not trying to jack this thread but I have a question regarding the tps. Is the connector supposed to be facing towards thdrivers side on all 3vze's? I put mine on the opposite wayby mistake and couldn't get it adjusted right until I turned it. I'm just wondering because my brother just bought a 95 runner and its facing the other way, it seems to be running great tho....

 

It's different year to year I have a 94' and mine faces towards the passenger side. I had it flipped (pointing towards the driver's side) when I was replacing it and the cruise cable would hit it. As long as you get the readings right you should be fine.

 

If you're simply using compressed air to blow out the passages, do you necessarily need to remove the TB to do it?

 

Removing the throttle body is pretty easy, and access to those ports is tight.

Plus, after I cleared it, I ran a lot of hot water through the ports tof flush it.

Pull the TB, it does not take but 10 minutes.

 

Will do. Thanks for the advice and writeup...

 

Excellent. I was having the same problem with my 3.0. In the middle of a HG replacement right now so I'll definitely check that out when I'm puttin her back together.

 

As luck would have it, I have an update related to this issue.

Yesterday I parked my truck and found coolant dripping out of it.

The coolant hose to the TB, in the front, had a hole in it. So, off to the dealer, bought new front/rear hoses and put them in last night.

Be careful with those hoses when removing the TB, other wise you will be making a trip to the dealer for a new one.

 

I'll make sure to re-inspect mine when I slap it back on. Thanks.

 

I did what you suggested today and it resolved the problem. She purrs like a kitten now. Thanks!!!

 

Tried this yesterday. Couldn't get to the back of that "plunger" thing, as the screws wouldn't budge and I didn't want to force it. What I DID find was a lot of sludge behind the throttle plate. I was TOLD that the intake was boiled out during rebuild. I HIGHLY doubt it. Anyhow, got the crap off the back of the butterfly valve and ran some Seafoam. All I seemed to accomplish was making the idle a bit higher! Opposite of what I was trying to achieve. My idle screw is officially all the way in and I idle at 1500 rpms in Park.

 

Those screws are a bear. I used a tool that you smack with a hammer and it rotates at the same time. Impact screw driver? I don't know the exact term. I replaced them with torx head M4's so that I could get them out easier.

Behind the plate there really is not much to clean, etc, as that is where the vacuum is present, no fluid behind there. Unless it is clogged in some way.

I assume you were able to flush water through the ports on the throttle body?

 

The coolant was free flowing.

 

any updates on this guys? I am also running at about 1100 RPM's with my idle screw all the way in.