Installed the 1zz throttle body - - Toyota Yaris Forums

FunctionSpec · 01-24-2009, 06:04 PM

You need to get all the air out of the coolant. Its important that you do. Gently squeeze the lines and get the air bubbles moving out of the coolant. Gently rev it to get the coolant flowing. A large air bubble can cause an air-lock in the coolant that prevents the coolant from flowing through the throttle body and back into the coolant system.

Air bubbles cause the oscillations because of the difference in temperature. Air heats up faster then coolant so whenever an air bubble passes over the coolant temp sensor, it lowers the idle thinking the engine is warmed up and then when the colder coolant passes over, it raises the idle thinking the engine is still cold.

ECU doesn't need to "learn" anything. It adjusts accordingly to how much air is flowing in. You will always have a high idle on a cold startup with this setup because the ecu doesn't start measuring airflow 10secs after startup. Once it does start measuring, it'll adjust the idle.

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01-24-2009, 06:04 PM	#11
FunctionSpec Super Newbie View User's Garage Drives: 2007 Yaris Liftback White Join Date: Jul 2007 Location: 626, Southern California Posts: 180	You need to get all the air out of the coolant. Its important that you do. Gently squeeze the lines and get the air bubbles moving out of the coolant. Gently rev it to get the coolant flowing. A large air bubble can cause an air-lock in the coolant that prevents the coolant from flowing through the throttle body and back into the coolant system. Air bubbles cause the oscillations because of the difference in temperature. Air heats up faster then coolant so whenever an air bubble passes over the coolant temp sensor, it lowers the idle thinking the engine is warmed up and then when the colder coolant passes over, it raises the idle thinking the engine is still cold. ECU doesn't need to "learn" anything. It adjusts accordingly to how much air is flowing in. You will always have a high idle on a cold startup with this setup because the ecu doesn't start measuring airflow 10secs after startup. Once it does start measuring, it'll adjust the idle.