FUEL INJECTION CONTROL OPERATION [L3 R.H.D.]

Operation

Injection timing

• There is synchronized fuel injection, which performs fuel injection by the setting of the crankshaft position, and non-synchronized fuel injection which performs fuel injection when the condition for fuel injection is met regardless of the crankshaft position.

• The crankshaft rotation is synchronized by each intake and exhaust stroke of the cylinders, and fuel injection is performed by the fuel injection timing and the injection amount corresponding to the input signals of the following sensors.

- CKP sensor

- MAF sensor

- ECT sensor

- IAT sensor

• The crankshaft rotation is not synchronized and fuel injection is performed by the injection timing and injection amount as triggered by the input signals of the following sensors.

- TP sensor

- MAF sensor

- ECT sensor

- IAT sensor

• If synchronized and non-synchronized fuel injection happen to occur together, fuel is injected by adding the fuel injection timing of both.

Injection time

Fuel injection time = effective injection time + 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 battery positive voltage. Accordingly, the PCM sets the non-injection time according to the battery voltage.

- The fuel injector opening valve time which is the actual fuel injection time is called the effective injection amount.

Determination of effective injection time

Start zone

• Improved startability

• When engine speed is 500 rpm or less

• According to engine coolant temperature (ECT sensor) and engine speed (CKP sensor)

Feedback zone

• Improved fuel economy

• Improved exhaust gas purification

• During engine operation except high load volume increase and engine start zones

• During normal driving, the amounts of various correction types are added to the basic injection time to set to the theoretical air/fuel ratio.

High load volume increase zone

• Improved driveability

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

• 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

• Engine protection

• When engine speed is 6,800 rpm or more

• When the engine speed is 5,500 rpm or more and the engine coolant temperature is approx. -10°C {14°F} or more.

• When the vehicle is stopped, engine speed is 4,000 rpm or more, and the engine coolant temperature is approx. 114°C {237°F} or more

Note

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

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

Deceleration fuel cut zone

• Improved fuel economy

• Prevents overheating of the catalytic converter.

• When the engine conditions are as follows (5 s or more has elapsed after shifting the selector lever to either D, S, or L, and 10 s or more has elapsed after engine start):

- Fully-closed throttle valve during deceleration (Charging efficiency at given value or more)

- While driving under load at engine speed of 1,000 rpm or more with charging efficiency at given value or more (MAF sensor normal)

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

Fuel injection time calculation method table

Calculation and determination method for fuel injection time and correction			Control zone
Injection time at start		Set value according to engine coolant temperature (low engine coolant temperature→long injection time)	*
Basic injection time		Basic injection time = charging efficiency x fuel flow coefficient		*	*
Fuel cut		Fuel injection time = 0				*	*
Ineffective injection time		Set time according to injector performance		*	*
Volume increase correction at engine start		Purpose: Ensures engine speed stability just after engine start Correction condition • Specified time according to engine coolant temperature directly after engine start Correction amount • Low engine coolant temperature→large correction • Low intake air temperature→large correction	x	x
Feedback correction		Purpose: Controls air/fuel ratio to theoretical air/fuel ratio Correction condition • Engine coolant temperature is at set value or more Correction amount • HO2S electromotive force is approx. 0.45 V or more→volume decrease correction • HO2S electromotive force is approx. 0.45 V or less→volume increase correction		x
D-range correction		Purpose: Ensures engine speed stability during D-range shifting Correction condition • Throttle valve is fully open and shifting in D range Correction amount • Low engine coolant temperature→large correction		x
Heavy load volume increase correction		Purpose: Improved engine output, decrease of exhaust gas temperature Correction condition • According to engine speed when the throttle valve opening angle is the fixed value or more, otherwise, according to engine speed and charging efficiency Correction amount • High engine speed, high charging efficiency→large correction			x
Warm-up volume increase correction		Purpose: Ensures combustion stability when engine coolant temperature is low Correction condition • While at set engine coolant temperature Correction amount • High charging efficiency, low engine coolant temperature→large correction	x	x	x
A/C and P/S increase correction		Purpose: Ensures engine speed stability during A/C and P/S operation Correction condition • A/C or P/S operating Correction amount • Low engine coolant temperature→large correction		x	x
Volume increase correction during acceleration		Purpose: Corrects fuel injection delay during acceleration, to ensure drive stability Correction condition • When 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		x	x
Deceleration volume increase correction		Purpose: Ensures engine speed stability after fuel cut and fuel cut recovery Correction condition • When suddenly entering deceleration fuel cut zone while driving with load, or recovery from fuel cut, the correction value is gradually increased to the set value Correction amount • After meeting deceleration fuel cut condition→volume decrease correction • During fuel cut recovery→volume increase correction					x
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		x	x

Fuel cut

Overspeed fuel cut

• To prevent overspeed

• Engine speed 4,000 rpm or more and vehicle speed at given value or more

Fuel cut at shift

• To reduce shock during shifting

• During shifting (performs fuel cut on cylinders 1 and 4)

Sensor malfunction fuel cut

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

• When damage to crankshaft position sensor or camshaft position sensor is detected

Dechoke control

• To improve engine startability when spark plugs are flooded.

• When cranking close to fully-open throttle valve