FUEL INJECTION AMOUNT CONTROL OPERATION [MZR-CD (RF Turbo)]

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Basic Injection Amount

Note

•  To avoid engine damage. Maximum injection amount is restricted (approx. 190 sec/Max.) not to over 3,000 rpm when engine coolant temperature is below -10 °C at engine ignition ON timing.

Operation

•  Fuel injection amount is controlled based on the fuel injector nozzle opening period.

Injection amount calculation

•  The PCM calculates the optimum fuel injection amount according to engine operation conditions.

•  The following two amount values are compared and the one of less amount is selected for the final injection amount.

Basic injection amount

•  The logically necessary injection amount is calculated based on the accelerator opening angle and engine speed.

Maximum injection amount

•  The maximum injection amount is calculated by correcting the basic injection amount based on driving conditions such as intake air pressure, intake air temperature, engine coolant temperature and barometric pressure.

Fuel injection learning

•  The PCM checks the variation in fuel injection amount by calculating fluctuations in engine speed. Based on the changes of the engine speed, the PCM corrects the fuel injection amount command value and increases/decreases the actual fuel injection amount for each cylinder to reduce engine speed variation.

•  The correction amount is stored in the PCM as a learning value.

•  The PCM stores the learning value until a new learning value is stored.

•  Fuel injection amount learning is performed at a high injection pressure.

•  Engine sound changes while performing fuel injection amount learning, however, do not indicate a malfunction.

Auto-learning

―  If all of the following conditions are met while idling, the PCM performs fuel injection amount learning every 150 km {93 mile} before the total travel distance reaches 1,500 km {932 mile}, and after that, every 3,000 km {1,864 mile}.

•  Shift lever is in neutral

•  Vehicle speed is 0 km {0 mph}

•  Engine coolant temperature is 65—95 °C {149—203 °F}

•  A/C is not operating

•  Accelerator opening angle is 0

•  Diesel particulate filter regeneration control has not been performed

―  Auto-learning is performed at a high injection pressure.

―  If any of above conditions are disabled during fuel injection learning, the learning is interrupted. However, if the conditions are met again, the learning will be resumed.

Using Mazda Modular Diagnostic System (M-MDS)

―  Fuel injection amount learning can be performed optionally by using the Mazda Modular Diagnostic System (M-MDS). Therefore, if the fuel injector or the PCM is replaced, the learning value can be stored again.

―  The learning is performed at a high injection pressure.

―  It is necessary to perform fuel injection amount learning (correction) periodically (once/year) to maintain the performance.