Odd throttle/RPM issue after cleaning IACV

[josephmama]

I cleaned the idle air control valve on my 2002 Avalon XLS on Wednesday evening, following the directions from a post of the Lexus Owners Club website. This involved removing the right throttle body, removing the IACV, and using q-tips and O2-Sensor-safe throttle body cleaner to clean the throttle body and IACV.

Everything fit back together nicely, no damaged gaskets, all clamps/hoses secure, and wires were properly plugged in. Car was idling properly both at cold start-up and after the engine is warmed up.

Thursday, I noticed that whenever I was driving down the road and took my foot off the gas (either to coast or to begin slowing down) the RPMs would immediately dip about 1k and then rise back to the "normal" RPM levels you would see while coasting. This appeared to be happened at most speeds. Other than this dip in RPMs when taking my foot off the gas, everything else is operating completely as expected. No acceleration issues, idling or stalling issues, or symptoms that the engine is getting shorted air.

Of course, the initial worry/scare is a transmission problem. However, I'm assuming (hoping) that one of the sensors got damaged or dirtied while I was cleaning everything.

Any ideas on what the problem could be? I've read online that the mass air-flow (MAF) sensor could be the problem, although I didn't remove or touch the airbox while doing the cleaning. Possibly a leaking gasket/o-ring? Or, one of the sensors on the throttle body?

Any help is much appreciated. Thank you.

[maun]

Is the O2 sensor near to what you were cleaning? I remember in my auto class that the O2 sensor could be affecting the engine as described (where the engine is searching for the right combination of air/gas mixture) meaning it is sending a mixed signals to the computer due to the O2 sensor pickup being dirty.

[josephmama]

I figured I'd reply and put this to rest. The throttle/RPM issue stopped after a day of driving. I am no expert on how the computer systems work in this vehicle, but perhaps the car "re-learned" the amount of force required to operate the freshly cleaned valve.

Or, perhaps any contaminants that may have been loosened during the cleaning eventually burned off or blew away.

Whatever the case, the car operates as expected