Stuck High Idle

Hey Everybody!
I was having an issue with the throttle getting stuck at higher RPM, which would go away if I revved the engine. So I took the throttle body apart and cleaned everything and now the problem I am having is the throttle is stuck at 2,000 RPM.
My first thought was the TPS, which I had taken off and put back on. So I checked the TPS with an Ohmmeter and it tested fine. It was on the lower end of the range, but within limits. I took the TPS off again and checked to see if there was something I may have done wrong in installing it, but I couldnt find anything. I also checked the Haines Manual and the FSM and didnt find anything super specific on installing the TPS, its really pretty simple to put on.
So then the next question, if the IAC was bad, would that cause the idle to be stuck high?
Ive double and triple checked and everything is on there correctly, so im wondering if that isnt the problem. Id like to get a little feedback before buying a new IAC and having that not be the issue.
Thanks!

 

In my Sienna I had the same what you have: idle high which goes away when I revved the engine. The IAC was dirty like a pig. Good cleaning took the problem away. My father's Opel IAC was in pieces when they opened it - the car was accelerating on 5th gear on it's own. When I was doing head gasket and had everything out I did clean IAC - same thing - it was dirty. Not that much as Sienna but I did preventive cleaning anyway.
So take IAC apart and clean it. Be careful it is quite delicate thing - no gorilla approach.

BTW Sienna which I bough used I suspect was driven through the desert with bad air filter as the whole intake was as dirty (dust).

 

I cleaned the IAC when took the throttle body apart the first time, the thing is nice and clean. So im not sure what the issue is...

 

Have you adjusted it according to the FSM?

 

Have you checked the diaphragm that is connected to the lower section of the IAC?
That diaphragm does dictate engine idle upon start.
I'm assuming you have the 2.7?

 

Mechanicjohn:
I dont have anything on the IAC in the FSM that I have. I was looking in the fuel injection section under throttle body and it only has information on the TPS, not the IAC. Mine may not be complete though being it was an internet download for a 2003. If you have anything on it for the 2.7 it would be greatly appreciated!

Ritchie:
Yeah its the 2.7, im assuming you talking about the diaphragm that hits the throttle stop screw? If so, then yes it is connected. I I dont see anything wrong with the hose either.

 

Just a suggestion.
If that diaphragm leaks, there is a possibility of high idle due to it being connected to the IAC which is controlled via coolant temps.

Good luck.

 

I just found the IAC inspection in the FSM, which consists of about a million abbreviated folders and files. Going to go run the test and see how it fares

 

So I tested the IAC according to the FSM (above), and it tested bad, the valve did not move. When I turned the ignition on I could feel power going to the motor, but the valve was not moving. So I went and got a new IAC and still the same thing when I went to test the new one. Not really sure what the problem would be, the procedure is super simple for testing and both IAC's were doing the same thing, not moving. Possibly not enough power to the IAC?

So heres question number 1. Would a bad IAC cause the idle to stick high? Today it started cold around 1400-1500 RPM and increased to about 1900 once the engine was at temperature.

I also tried while the engine was running disconnecting the vacuum line from the throttle opening diaphragm. Not much of a change there, but while the engine is running there is about 5mm of clearance between the stop screw and the rod coming from the diaphragm. There is zero clearance when the engine is off. Id imagine that fine because vacuum is going to pull that rod away from the stop screw.

Im gonna go mess around with this thing some more and try and figure it out. Any ideas or feedback are greatly appreciated

Thanks

 

Yes, an IAC can "stick" in any position. Not likely 2 in a row. Try the tests again.
and
The "throttle opener" should hold the throttle plate open a tad when the engine is off. With vacuum (engine on), it should pull the throttle against the stop.
All this can be found in your (online) 03 FSM under...... repair > sf2rzfe3 > thrbod.

The throttle opener is a stand alone "system". It holds the throttle open a bit via a light spring when the engine is off to allow a little extra intake air while starting. As soon as full manifold vacuum is developed the diaphragm overcomes the spring and allows the throttle to close fully. It is only purpose in life is more efficient starting. If the TO is bad/leaks or there is a vacuum leak in the line it could allow the throttle plate to stay slightly open. The resultant extra air would be more than the ECM controled IAC could compensate for.

 

Does anybody know if there is any special procedure for installing the throttle position sensor? When I reinstalled it the tab that is connected to the throttle valve was straight up and down (12 and 6 o'clock). This required rotating the sensor to about 2:00 in order to line it up with the tab, and then rotating it counterclockwise to get the screws to line up again.
I looked in the Haines manual and the FSM and didnt see anything specific aside from the values to test the TPS once its installed.
Thanks

 

Thanks, ill try the tests again. Im not sure why it wouldnt work. Ill have to run a multi meter to the connector and see if everything is correct there.

 

That sounds right, not super familiar with the 4 bangers.
IIRC the only 1st gen TPS that needs adjustment/calibration has slotted holes for the mount screws, engines/years not on the tip of my tongue.

 

Upon further inspection I discovered a little bit of play in the throttle valve, seems it must be worn. Looking on forums ive seen a lot of these high idle problems sprout up after cleaning the throttle bodies. I wonder if cleaning them gets that little bit of gunk off that helped make a better seal on a worn throttle body.

Heres my question: Is there anywhere that makes a throttle body rebuild kit for these things? I cant seem to find one.

My next bet may be to replace the throttle valve, which seems to be the worn piece. i just need to find a parts catalog with a part number for the actual valve piece, which would be an easy replacement. Anybody have any experience with a work throttle body?

 

Try Maxbore.com

 

Don't know of any rebuild kits myself. Maybe a used throttle body.

 

Are you sure you were unhooking the correct ECT sensor?

 

Is there more than one ECT? I unhooked the Engine Coolant Temp Sensor thats behind the block. If I understand correctly it just makes the engine think its running hot when the ECT is unplugged, which should open the IAC.

 

Thanks! Ill check it out.

Still no luck with anything ive tried today. The idle has calmed down to about 1,250 from just under 2,000. Its still kind of erratic though. For instance if I coming up to a stop light and I shift into Neutral the RPMs go down to about 1,100 and then surge a couple times before settling back down.
I gonna give it a couple days and see if it settles in, I double checked all the vacuum lines today and blew them all out. Didnt find anything there.
My guess, if nothing changes is the little bit of play in the throttle valve is letting enough air in to make it idle 500 or so RPM high and the IAC is doing its job correctly. Here are a couple pictures of the throttle valve, its got some play horizontally, so you can see the change in light getting through when you move it left to right.

 

That's a huge gap. You can't get it to close any tighter?