Multiplicative adaptation
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Multiplicative adaptation
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If the closed loop system continuously corrects a deviation in the fuel system, it will be adapted. Adaptation takes place every five minutes and takes 30 seconds.
The fuel quantity is always multiplied by a multiplicative adaptation factor which is 1.00 when the control module is new or de-energized. Multiplicative adaptation takes place under conditions of partial load. Purging is stopped during adaptation because no other factor that can affect the fuel must be active.
The entire closed loop deviation from 1.00 is transferred to the multiplicative adaptation factor. This means that the correct quantity of fuel is injected even when closed loop is not active, such as during cold starting or driving with full load. Once the engine has started, a multiplicative adaptation must be performed before an additive. The limits for multiplicative adaptation are 0.75 and 1.25.
The following conditions must be fulfilled for multiplicative adaptation to take place:
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No purging in progress; this takes place for 4 minutes and 30 seconds during each 5 minute period. However, a multiplicative adaptation will be performed the first time all the other conditions are fulfilled.
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The coolant temperature must exceed 75 °C.
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Engine speed 1500-2750 rpm.
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Engine load 175-350 mg/c.
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If the correction factor reaches 1.25 (25%), diagnostic trouble code P0171 will be generated.
The fault may have been caused by:
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Faulty mass air flow sensor.
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If the correction factor reaches 0.75 (-25%), diagnostic trouble code P0172 will be generated.
The fault may have been caused by:
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Air leakage between compressor and throttle.
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Faulty mass air flow sensor.
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