The engine control module (ECM) learns the airflow through the throttle body to ensure the correct idle. The learned airflow values are stored within the ECM. These values are learned to adjust for production variation and will continuously learn during the life of the vehicle to compensate for reduced airflow due to throttle body coking. Anytime the throttle body airflow rate changes, for example due to cleaning or replacing, the values must be relearned.
An engine that had a heavily coked throttle body that has been cleaned or replaced may take several drive cycles to learn out the coking. To accelerate the process, the scan tool has the ability to reset all learned values back to zero. A new ECM will also have values set to zero.
The idle may be unstable or a DTC may set if the learned values do not match the actual airflow.
Note:
Do NOT perform this procedure if DTCs are set. Refer to Diagnostic Trouble Code (DTC) List - Vehicle.
Note:
During the drive cycle the check engine light may come on with idle speed DTCs. If idle speed codes are set, clear codes so the ECM can continue to learn.
Additional Maintenance and Care
Your vehicle is an important investment and caring for it properly may help to
avoid future costly repairs. To maintain vehicle performance, additional maintenance
services may be required.
It is recommended that your dealer perform these services — their trained dealer
technicians know you ...
Exhaust Rear Muffler Replacement (LUV,LUW)
Special Tools
CH-6614 Chain Pipe Cutter
For equivalent regional tools, refer to Special Tools.
Removal Procedure
Warning: Refer to Exhaust Service Warning.
Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.
Cut the exhaust rear mu ...
Air Intake System Description
Circuit/System Description
The primary function of the air intake system is to provide filtered air
to the engine. The system uses a filter element mounted in a housing. The filter
housing is remotely mounted and uses intake ducts to route the incoming air
into the throttle body. T ...