SOLVED: High idle, increases with coolant temp - IAC?

[Wolfhound_Actual]

FYI, I just solved my high idle issues using a combination of this thread and this video -> Toyota Idle Air Control Valve Maintenance (Correct Idle & Cold Start Issues) | AnthonyJ350 - YouTube

Just bought a 97 Limited 4x4 and it was idling high from the start. PO mentioned that he cleaned the IAC so he thought it was a temp sensor. Bought an OBD reader, downloaded Torque Pro and verified temps were correct and ECU was going into Closed Loop. Probably not the CTS.

Turned back to the IAC. Used Tim's video to test my IAC and everything checked out electrically and otherwise. Kept reading and saw the issue plaguing Spiker and started looking up Youtube videos on how to service the IAC. I figured I needed a new one anyway so what's the harm in seeing what I could do to save this one?

In the video the guy disconnects his vacuum hose, removes the electrical coil and then hand tests how freely the valve moves. Mine was stuck solid. I stuck a rag under the IAC and started blasting TB cleaner down into the IAC port while simultaneously wiggling the valve stem back and forth. About 5 seconds it the valve broke loose and an insane amount of carbon POURED out of the bottom port of the IAC. I flushed it 3 times and it moved silky smooth.

Put everything back together and now it runs perfect. Thank you everyone for this detailed thread. Saved me a bunch of time and got my 97 running perfect again!

 

[Spiker Engineering]

FYI, I just solved my high idle issues using a combination of this thread and this video -> Toyota Idle Air Control Valve Maintenance (Correct Idle & Cold Start Issues) | AnthonyJ350 - YouTube

Just bought a 97 Limited 4x4 and it was idling high from the start. PO mentioned that he cleaned the IAC so he thought it was a temp sensor. Bought an OBD reader, downloaded Torque Pro and verified temps were correct and ECU was going into Closed Loop. Probably not the CTS.

Turned back to the IAC. Used Tim's video to test my IAC and everything checked out electrically and otherwise. Kept reading and saw the issue plaguing Spiker and started looking up Youtube videos on how to service the IAC. I figured I needed a new one anyway so what's the harm in seeing what I could do to save this one?

In the video the guy disconnects his vacuum hose, removes the electrical coil and then hand tests how freely the valve moves. Mine was stuck solid. I stuck a rag under the IAC and started blasting TB cleaner down into the IAC port while simultaneously wiggling the valve stem back and forth. About 5 seconds it the valve broke loose and an insane amount of carbon POURED out of the bottom port of the IAC. I flushed it 3 times and it moved silky smooth.

Put everything back together and now it runs perfect. Thank you everyone for this detailed thread. Saved me a bunch of time and got my 97 running perfect again!

Good sleuthing, and I'm glad this thread helped you out, that was the intent!

Interestingly, I watched the Youtube video you linked while trying to figure out my issue. I didn't really think it applied because unlike his IAC, mine did move, in both directions. And also passed all electrical tests.

What I didn't realize, until I fully took the IAC apart, was that while it did move, it did not move through the entire range of motion, because the carbon that I disturbed during cleaning reconstituted itself on one place, preventing the IAC from closing.

Live and learn!

 

[haughk]

Bitten by IAC cleaning

After cleaning my IAC (as part of valve cover gasket/cam plug reseal), I experienced the same high issue that Leon described. Cleaned it again using cotton swab and carefully holding the spool wide open and wiping the back edge-solved the issue.
I did disconnect the electrical connector while running and the idle dropped to 1,000 rpm. This would lead to the logical inference that the electrical signal was opening the IAC-and might cause one to seek influencing options.., like EFI coolant temp sensor, etc.
I may never fully understand why the electrical connection seemed to open the spool port, but the recleaning solved the problem. Dang electrical influence just led to head spinning confusion-while a bit of carbon crust was evidently the culprit. Thanks to Timmy and Leon for sharing valuable info.