Resetting adaption values

Engine control module (ECM) has self-learning functions (adaptions) for, e. g., idle and air control, knock control, heated oxygen sensor control and misfire diagnosis. The values for these functions (adaptions) are reset at the following events:

• Replacing the engine control module (ECM).
• Downloading software to Engine control module (ECM).
• After erasing diagnostic trouble codes.
• The control module has been without voltage.

For the engine management system to work as intended, the system must in certain cases be given time to adapt. When and how the system adapts may differ between different systems and functions.

When driving with a system that hasn't had time or possibility to adapt itself, certain "abnormal" behaviors can be experienced. It may be that, e. g., the idle RPM is uneven, that the engine knocks more than at normal throttle application or that the RPM oscillates during engine braking. The symptoms that occur are to a certain extent also dependent on which engine management system the engine has. Further down in the document there are system-unique symptoms.

There are also cases that do not affect driveability which should be considered in connection with repairs. If you are to, e. g., verify a repair, where adaptions have just reached their maximal values, you must give these adaptions time to adjust before you can conclude if the problem has been solved or not. If you are to, e. g., verify a repair where misfire diagnostic trouble codes have been generated, you have to make sure that the adaption of the flywheel's variations is finished, otherwise you cannot decide if the problem has been solved or not. See description for each diagnostic function to be clear on how to drive to adapt each function.

5-cyl. non-turbo engines 

The RPM is high/low during engine braking to a stop. This is so because idle control needs time to learn how much air the engine needs when the engine runs at idle. The adaption takes place every time the engine idles. Only a limited amount of adaptions is allowed each time. This means that you have to leave idle every once in awhile for the system to finish adapting.

• One way to do that is to run the engine warm and then let it idle. If the vehicle is equipped with automatic transmission, gear position D (drive) shall be used.
• With some minute's interval, load the engine a little by revving it for a few seconds. Then you let the engine return down to idle.
• Test-drive the vehicle to decide if the system has finished adapting or not.

Turbo engines and 6-cyl non-turbo engines 

Rough idling, the RPM varies when idling/retardation and/or the RPM drops sharply during engine braking to a stop. This is so because air control needs a little time to learn how much air the engine needs in different positions.

• For the adaption to be performed, the engine has to be warm, adaption needs to be performed with and without gear as well as with and without AC. The adaption is only allowed to take a few steps every time the system is in the range when it is allowed to adapt. It means that you have to vary load/RPM every once in awhile for the system to finish adapting.
• To adapt the system, vary driving with different driving scenarios, at idle, part load and with engine brake. This should be repeated until the engine's behavior feels good.

• Continue 

  Refer to Information