Re 1999 Avalon V6
Many articles and DIY videos say you can eliminate low and/or rough idle by cleaning the IAC valve and throttle body. Why does this work? The ECU is always comparing sensed rpms to target values in the look-up table. If rpm is too low, the ECU changes IAC duty cycle to get the correct target speed. If the IAC passages are restricted, wouldn’t the ECU simply open the IAC to compensate? I am not talking about a sticking IAC valve which causes abrupt rpm changes or a no cold start because it can not open at all. The ECU can not compensate for this condition.
Many articles and DIY videos say you can eliminate low and/or rough idle by cleaning the IAC valve and throttle body. Why does this work? The ECU is always comparing sensed rpms to target values in the look-up table. If rpm is too low, the ECU changes IAC duty cycle to get the correct target speed. If the IAC passages are restricted, wouldn’t the ECU simply open the IAC to compensate? I am not talking about a sticking IAC valve which causes abrupt rpm changes or a no cold start because it can not open at all. The ECU can not compensate for this condition.