Multiplicative adaptation
|
|
Multiplicative adaptation
|
If closed loop continuously corrects a deviation in the fuel system, it will be adapted. Adaptation occurs every 5 minutes and takes 30 seconds.
The fuel quantity is always multiplied by a multiplicative adaptation factor that is 1.00 when the control module is new or has been de-energized. The multiplicative adaptation takes place during partial load. Purging is interrupted during adaptation as no other sources affecting the fuel may be present.
The entire closed loop variation from 1.00 is transferred to the multiplicative adaptation factor. This results in the correct amount of fuel being injected even though the closed loop is not active, for example on cold starts or when driving with a full load. After the engine has been started a multiplicative adaptation must always occur before an additive. The limits for the multiplicative adaptation are 0.75 and 1.25 respectively.
The following conditions must be fulfilled before multiplicative adaptation can take place:
|
•
|
No purging in progress; this takes place for 4 minutes and 30 seconds during each 5-minute period. However, a multiplicative adaptation will take place directly the first time the other conditions have been fulfilled.
|
|
•
|
Engine coolant temperature exceeds 80°C.
|
|
•
|
Engine speed 1200-2750 rpm.
|
|
•
|
Engine load 130-310 mg/c.
|
|
•
|
If the correction factor reaches 1.25 (25%), diagnostic trouble code P0171 will be generated.
The fault can be caused by:
|
|
|
-
|
Defective mass air flow sensor.
|
|
•
|
If the correction factor reaches 0.75 (-25%), diagnostic trouble code P0172 will be generated.
The fault can be caused by:
|
|
|
-
|
Air leak between the compressor and the throttle.
|
|
|
-
|
Defective mass air flow sensor.
|
