Automotive Forums  Where Car Enthusiasts Go to Discuss Cars Online

I have a '98 Camry with 200K+ miles.  Starts fine but just as the temperature needle reaches the bottom of the operating zone the idle will drop and the car stalls.  It will generally restart without problem but the same problem repeats when it reaches the full, normal operating temperature.
Have replaced plugs, wires, coil blocks and Idle Air Control.  Air filter is good.  

carefully tag the various hoses that connect to the bottom of the throttle body...

remove the throttle body....


flip it over..

remove the idle air control valve...    remove the electric section from the end of the idle air control valve... this gives you a knob to turn with your fingers..    you can then use brake cleaner or carb cleaner spray... to clean the carbon off the shutter valve

this is what controls the idle speed....

it cannot be properly cleaned with the whole thing assembled..    you can replace the idle air control valve.. but its over 200 bucks. and it usually just needs to be cleaned...


wait.. you already replaced it???? are you sure???   did you clean the throttle bore also????

idle speed is controlled by the idle air valve.. the ECM sends a small voltage to the electric part.. this causes the knob to turn slightly.. opening or closing..  any carbon  can cause it to hang up...

do you have an OBD2 scan tool that displays live data stream .. so you can watch the

throttle position sensor signal... TPS.

engine coolant temp...   ECT..

i don't recall if you can see the idle air voltage.. or percentage..

is there a chance of any vacuum leaks.?

i will have to look at the camry manual i have stashed in my computer somewhere see if i can find the proper voltage for the TPS...  

I second wayne on his post above, we always start by cleaning throttle body and then reset base idle and go from there.