FUEL INJECTION CONTROL OPERATION [MZR 2.0 DISI]

id0140j3101900

Operation

Injection timing

•  A synchronized fuel injection at the set crank position is performed.

Synchronized fuel injection

•  Fuel injection is performed with the appropriate injection timing and amount based on the below sensor input signals synchronized with the crankshaft rotation during the intake air process at each cylinder.

―  CKP sensor

―  MAF sensor

―  ECT sensor

―  IAT sensor

―  BARO sensor

Injection Time

•  The fuel injectors cause an operation delay with the start of energization from the PCM. The PCM calculates the fuel injection time by adding the non-injection time (ineffective injection time) to the actual injection time (effective injection time), and energizes the fuel injectors for this time.

acxuun00000052

Ineffective injection time

―  The fuel injectors cause an operation delay due to a delay in the rise of operation current due to coil inductance at the start of energization, and by the mass of the needle valve and plunger, and spring resistance. This delay is the ineffective injection time.

―  The non-injection time is affected by the change in fuel pressure. Accordingly, the PCM sets the non-injection time according to the fuel pressure.

Effective injection time

―  The fuel injector opening valve time, which is the actual fuel injection time, is called the effective injection time.

Determination of effective Injection Time

•  The PCM divides the engine operation conditions into control zones according to engine speed and engine load, and determines the effective injection time at each control zone to perform optimum air/fuel ratio control in all engine driving ranges.

am3zzn00002816

Start zone

Purpose

•  Improved startability

Control condition

•  When engine speed is 500 rpm or less

Determination of fuel injection time

•  Determination is based on the engine coolant temperature (ECT sensor) and engine speed (CKP sensor)

Feedback zone

Purpose

•  Improved fuel economy

•  Improved exhaust gas purification

Control condition

•  Occurs during engine operation except for high load volume increases and engine start zones

Determination of fuel injection time

•  During normal driving, the various correction amounts are added to the basic injection time to obtain the ratio that is close to the theoretical air/fuel ratio.

High load volume increase feedback zone

Purpose

•  Improved driveability, exhaust system component protection (suppress gas temperature)

Control condition

•  Either the charging efficiency or the accelerator opening angle is a given value or more.

Determination of fuel injection time

•  Corrections are added to the basic injection amount and the high load coefficient is calculated according to the engine speed, mass intake airflow amount and the throttle valve opening angle.

Excessive speed fuel cut zone

Purpose

•  Engine protection

Control condition

•  When the engine speed is 6,700 rpm or more.

•  When engine speed is 5,500 rpm or more and the engine coolant temperature is approx. -15 °C {5 °F} or less.

•  All of the following conditions are met while the vehicle is stopped.

―  Engine speed of 1,500 rpm or more and ECT is 40 °C {104 °F} or more continues for 5 min.

―  Engine speed of 3,500 rpm or more and ECT is 40 °C {104 °F} or more continues for 2 min.

―  The engine speed is maintained at 4,500 rpm or more when the shift lever is in the neutral position. (ATX)

Note

•  The PCM determines that the driver continues to unintentionally depress the accelerator pedal

Determination of fuel injection time

•  The fuel injection time is set to 0 (fuel cut).

Deceleration fuel cut zone

Purpose

•  Improved fuel economy

•  Prevents overheating of the catalytic converter.

Control condition

•  When the engine conditions are as follows10 s or more has elapsed after engine start).

―  Accelerator pedal position is fully closed

―  Engine speed is the set value or more (charging efficiency at given value or more, mass airflow sensor normal).

Determination of fuel injection time

•  The fuel injection time is set to 0 (fuel cut)

Fuel injection time calculation method table

Contents (Fuel injection time, calculation method, or determination method)			Control zone
Injection time at start		Set value according to engine coolant temperature (low engine coolant temperature→long injection time)	A
Basic injection time		Basic injection time = charging efficiency x fuel flow coefficient		A	A
Fuel cut		Fuel injection time = 0				A	A
Ineffective injection time		Set time according to injector performance	A	A	A
Volume increase correction at engine start		Purpose: Ensures engine speed stability just after engine start Correction condition •  Specified time according to the engine coolant temperature directly after engine start Correction amount •  Low engine coolant temperature→large correction •  High intake air temperature→large correction	B	B
A/F sensor feedback correction		Purpose: Controls air/fuel ratio to target air/fuel ratio Correction condition •  When the engine coolant temperature is at the set value or more Correction amount •  A/F sensor current value 0 mA or less→volume decrease correction •  A/F sensor current value 0 mA or more→volume increase correction		B
HO2S feedback correction		Purpose: Controls air/fuel ratio to theoretical air/fuel ratio correction condition Correction condition •  When the engine coolant temperature is at the set value or more Correction amount •  HO2S voltage value 0.45 V or less→volume increase correction •  HO2S voltage value 0.45 V or more→volume decrease correction		B
High load value increase feedback correction		Purpose: Improved engine output, decrease of exhaust gas temperature Correction condition •  Based on the engine speed when the accelerator opening angle is the fixed value or more, otherwise, based on the engine speed and charging efficiency. Correction amount •  High engine speed, high charging efficiency→large correction			B
Warm-up volume increase correction		Purpose: Ensures combustion stability when the engine coolant temperature is low Correction condition •  While at the set engine coolant temperature Correction amount •  High charging efficiency, low engine coolant temperature→large correction		B	B
A/C load increase correction		Purpose: Maintains engine speed stability during A/C operation Correction condition •  A/C is operating Correction amount •  Low engine coolant temperature→large correction		B	B
Volume increase correction during acceleration		Purpose: Corrects fuel injection delay during acceleration, to ensure drive stability Correction condition •  When the acceleration amount (change in the amount of charging efficiency) is at the set value or more. Correction amount •  Low engine coolant temperature→large correction •  Large acceleration amount→large correction		B	B
Learning correction		Purpose: Corrects deviation in air/fuel ratio from deterioration over time of mechanical devices Correction condition •  Under any condition except purge control Correction amount •  Learning value based on average of feedback correction value		B	B
Deceleration volume increase correction		Purpose: Ensures stability of engine speed during recovery from fuel cut Correction condition •  Recovery from deceleration fuel cut Correction amount •  High engine speed→small correction		B

Fuel Cut

Sensor damage fuel cut

Purpose

•  To prevent engine damage from abnormal ignition due to a malfunction input of a cylinder identification or the engine speed signal.

Execution condition

•  DTC stored for the following devices:

―  CKP sensor

―  CMP sensor

Dechoke Control

Purpose

•  To improve engine starting startability when spark plugs are flooded.

Execution condition

•  When cranking close to fully-open throttle valve

Boost Circuit

Output Circuit

Fuel injector status	Injector driver module operation
Opening starts	1.  Provides 65 V, boosted by the boost circuit, to the opening transistor (65 V output). 2.  When the voltage is provided to the fuel injector and turns on the GND transistor, the fuel injector opens. 3.  After the fuel injector is opened, the opening transistor is turned off.
Opening held	•  Controls the on/off of the holding transistor (12 V output) so that the hold current of the fuel injector is constant.
Closing	•  Turns off the holding and GND transistors at the same time the fuel injection signal from the PCM is stopped, and cuts the current.