Multiplicative adaptation
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Multiplicative adaptation
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If the closed loop system continuously corrects a variation 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 disconnected. 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 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 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 take place directly the first time the other conditions have been fulfilled.
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Engine coolant temperature exceeds 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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