FUEL INJECTION AMOUNT CONTROL OPERATION [MZR-CD 2.2]

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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 {14 °F} 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/low 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 60—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/low 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/low injection pressure.

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

Brake Override System (From BL****-198281, BL1***-239890)

Operation of brake override system

•  The brake override system gives priority to the brake operation if a malfunction occurs with the accelerator pedal such as if the accelerator pedal is depressed and does not return. The fuel injection amount is controlled if the brake pedal is depressed while the accelerator pedal is in a depressed condition until the vehicle is safely decelerated and comes to a complete stop.

Brake override operation conditions

•  If either one of the following conditions is met with the brake pedal depressed for 1 s or more while the accelerator pedal is depressed, the PCM controls the fuel injection amount so that the engine speed is the specification*. While driving vehicle ―  Accelerator pedal opening angle: 5 % or more from fully-closed ―  Vehicle speed: 10 km/h {6.2 mph} or more ―  In gear ―  Engine speed: 1,150 rpm or more While vehicle stopped ―  Accelerator pedal opening angle: 5 % or more from fully-closed ―  Shift lever position: neutral ―  Engine speed: 1,150 rpm or more

End brake override operation

•  If the following conditions are met while operating the brake override system, the PCM stops the operation of the brake override system and controls the throttle valve opening angle in accordance with the fuel injection amount. ―  Accelerator pedal is not depressed ―  Brake pedal is not depressed Note •  Cycling the key off and back on will also end brake override operation.

Disabling of brake override system

•  If the servicing procedure requiring the brake pedal and the accelerator pedal to be depressed together, operation of the brake override system can be prevented, if necessary.

Disable brake override operation conditions	•  If the following conditions are met for 10 s within 30 s after switching the ignition ON (engine off), the brake override system is disabled until the activate brake override operation conditions are met. ―  Shift lever position: neutral ―  Vehicle speed: 0 km/h {0 mph} ―  Accelerator pedal fully depressed ―  Brake pedal depressed
Activate brake override operation conditions	•  Cycling the key off and back on will activate the brake override operation conditions.

Brake system warning light illumination request

•  If the following conditions are met, the PCM sends the brake system warning light illumination request signal to the instrument cluster. The brake system warning light illuminates to alert the driver that there is a malfunction in the brake system.

―  Malfunction in brake switch No.1 and 2 or both is detected