1997 - 2001 Toyota Camry 5SFE Cold Start / Idle Air Control (IAC) Stall Problems
A common but simple cold weather problem with the 4 cylinder 5SFE model Camry is the Idle Air Control (IAC) valve sporadically sticking. This value should close during cold engine start up to restrict air flow. Restricted air flow will provide a rich air/fuel mixture and prevent engine stalls. A rich mixture should normally result in a higher than normal idle speed (approximately 1,400 - 1,600 rpm's). The rpm's will drop as the engine warms up. If your cold engine starts and stays at around 850 rpm's then eventually stalls, the IAC is stuck in the open position due to carbon and varnish buildup accumulated by blow by gases. This buildup can be dissolved by spraying carburetor cleaner solvent in the IAC port which is located as a small rectangular port opening in the mouth of the throttle body. Access to this port can be made by disconnecting the Throttle Body to Airbox Hose Clamp, twisting and pulling the hose off and then pushing the hose away from the throttle body opening. Apply a liberal amount of solvent in the port opening. Re-connect the hose and turn-on and off the engine a few times to allow the IAC valve to work loose the carbon and varnish build up. As the solvent is being burned off, some smoke will blown out through the exhaust pipe. If non of the above fixes the problem, consider replacing the IAC which will require removal of the throttle body assembly.
Camry I4 5SFE Throttle Body & Idle Air Control (IAC) Cleaning Video
This video will show you how to remove and clean the throttle body on Toyota vehicles with the 4 cylinder 5-SFE engine typically found on the older model Camry, RAV4 and Celica. Over time, the carbon buildup can make the throttle body plate "stick" resulting in engine response lag, the plate opening too much or too fast and erratic idle. Since the Idle Air Control valve (IAC) is attached to the bottom of the throttle body, removing the throttle body gives us the opportunity to clean this component as well. A stuck IAC valve will result in a too high or too low engine idle, rough idle and engine stall during warm up. The carbon build up is the result of PCV and EGR gases being sucked in or injected into the intake manifold and backing up against the throttle body's throttle plate and components. To reduce carbon buildup, you can install an aftermarket oil catch can.