Toyota
Nissan Versa
 Sedan Service Manual
Engine » Engine control system (EC)
Multiport fuel injection system

MULTIPORT FUEL INJECTION SYSTEM : System Diagram

MULTIPORT FUEL INJECTION SYSTEM : System Diagram

MULTIPORT FUEL INJECTION SYSTEM : System Description

INPUT/OUTPUT SIGNAL CHART

Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor (POS) Engine speed*4 Piston position Fuel injection & mixture ratio control Fuel injector
Camshaft position sensor (PHASE)
Mass air flow sensor Amount of intake air
Intake air temperature sensor Intake air temperature
Engine coolant temperature sensor Engine coolant temperature
Air fuel ratio (A/F) sensor 1 Density of oxygen in exhaust gas
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Park/neutral position (PNP) switch*1 PNP signal
Transmission range switch*2
Battery Battery voltage*4
Knock sensor Engine knocking condition
Heated oxygen sensor 2*3 Density of oxygen in exhaust gas
EPS control unit EPS operation signal*5
Combination meter Vehicle speed*5
BCM A/C ON signal*5 Blower fan signal*5

*1: M/T models *2: A/T models or CVT models *3: This sensor is not used to control the engine system under normal conditions.

*4: ECM determines the start signal status by the signals of engine speed and battery voltage.

*5: This signal is sent to the ECM through CAN communication line.

SYSTEM DESCRIPTION

The amount of fuel injected from the fuel injector is determined by the ECM. The ECM controls the length of time the valve remains open (injection pulse duration). The amount of fuel injected is a program value in the ECM memory. The program value is preset by engine operating conditions. These conditions are determined by input signals (for engine speed and intake air) from the crankshaft position sensor, camshaft position sensor and the mass air flow sensor.

VARIOUS FUEL INJECTION INCREASE/DECREASE COMPENSATION

In addition, the amount of fuel injected is compensated to improve engine performance under various operating conditions as listed below.

<Fuel increase>

  • During warmup
  • When starting the engine
  • During acceleration
  • Hotengine operation
  • When selector lever position is changed from N to D (A/T models or CVT models)
  • Highload, highspeed operation

<Fuel decrease>

  • During deceleration
  • During high engine speed operation

MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)

MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)

The mixture ratio feedback system provides the best airfuel mixture ratio for drivability and emission control.

The three way catalyst (manifold) can better reduce CO, HC and NOx emissions. This system uses A/F sensor 1 in the exhaust manifold to monitor whether the engine operation is rich or lean. The ECM adjusts the injection pulse width according to the sensor voltage signal. This maintains the mixture ratio within the range of stoichiometric (ideal airfuel mixture).

This stage is referred to as the closed loop control condition.

Heated oxygen sensor 2 is located downstream of the three way catalyst (manifold). Even if the switching characteristics of A/F sensor 1 shift, the airfuel ratio is controlled to stoichiometric by the signal from heated oxygen sensor 2.

  • Open Loop Control The open loop system condition refers to when the ECM detects any of the following conditions. Feedback control stops in order to maintain stabilized fuel combustion.
  • Deceleration and acceleration
  • Highload, highspeed operation
  • Malfunction of A/F sensor 1 or its circuit
  • Insufficient activation of heated sensor 1 at low engine coolant temperature
  • High engine coolant temperature
  • During warmup
  • After shifting from N to D (A/T models or CVT models)
  • When starting the engine

MIXTURE RATIO SELFLEARNING CONTROL

The mixture ratio feedback control system monitors the mixture ratio signal transmitted from A/F sensor 1.

This feedback signal is then sent to the ECM. The ECM controls the basic mixture ratio as close to the theoretical mixture ratio as possible. However, the basic mixture ratio is not necessarily controlled as originally designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and characteristic changes during operation (i.e., fuel injector clogging) directly affect mixture ratio.

Accordingly, the difference between the basic and theoretical mixture ratios is monitored in this system. This is then computed in terms of "injection pulse duration" to automatically compensate for the difference between the two ratios.

"Fuel trim" refers to the feedback compensation value compared against the basic injection duration. Fuel trim includes "shortterm fuel trim" and "longterm fuel trim".

"Shortterm fuel trim" is the shortterm fuel compensation used to maintain the mixture ratio at its theoretical value. The signal from A/F sensor 1 indicates whether the mixture ratio is RICH or LEAN compared to the theoretical value. The signal then triggers a reduction in fuel volume if the mixture ratio is rich, and an increase in fuel volume if it is lean.

"Longterm fuel trim" is overall fuel compensation carried out longterm to compensate for continual deviation of the "shortterm fuel trim" from the central value. Such deviation will occur due to individual engine differences, wear over time and changes in the usage environment.

FUEL INJECTION TIMING

FUEL INJECTION TIMING

Two types of systems are used.

  • Sequential Multiport Fuel Injection System Fuel is injected into each cylinder during each engine cycle according to the firing order. This system is used when the engine is running.
  • Simultaneous Multiport Fuel Injection System Fuel is injected simultaneously into all four cylinders twice each engine cycle. In other words, pulse signals of the same width are simultaneously transmitted from the ECM.

    The four injectors will then receive the signals two times for each engine cycle.

    This system is used when the engine is being started and/or if the fail safe system (CPU) is operating.

FUEL SHUTOFF

Fuel to each cylinder is cut off during deceleration, operation of the engine at excessively high speeds or operation of the vehicle at excessively high speeds.

    More about «Engine control system (EC)»:

    Precaution

    Engine control system

    Structure and operation

    Engine control system

    Multiport fuel injection system

    Electric ignition system

    Air conditioning cut control

    Cooling fan control

    Evaporative emission system

    Intake valve timing control

    Exhaust valve timing control

    Engine protection control at low engine oil pressure

    Fuel filler cap warning system

    Automatic speed control device (ASCD)

    Automatic speed control device (ASCD)

    Diagnosis description

    Ecm

    Diagnosis and repair workflow

    Additional service when replacing ECM

    Accelerator pedal released position learning

    Throttle valve closed position learning

    Idle air volume learning

    Mixture ratio selflearning value clear

    Basic inspection

    Fuel pressure check

    How to set SRT code

    How to erase permanent DTC

    Trouble diagnosis specification value

    Power supply and ground circuit

    U0101 can comm circuit

    U1001 CAN comm circuit

    P0011 IVT control

    P0014 EVT control

    P0031, P0032 A/F sensor 1 heater

    P0037, P0038 HO2s2 heater

    P0075 IVT control solenoid valve

    P0078 EVT control solenoid valve

    P0101 MAF sensor

    P0102, P0103 MAF sensor

    P0111 IAT sensor

    P0112, P0113 IAT sensor

    P0116 ECT sensor

    P0117, P0118 ECT sensor

    P0122, P0123 TP sensor

    P0125 ECT sensor

    P0127 IAT sensor

    P0128 thermostat function

    P0130 A/F sensor 1

    P0131 A/F sensor 1

    P0132 A/F sensor 1

    P0137 HO2s2

    P0138 HO2s2

    P0139 HO2s2

    P014C, P014D, P015A, P015B, A/F sensor 1

    P0171 fuel injection system function

    P0181 FTT sensor

    P0182, P0183 FTT sensor

    P0196 EOT sensor

    P0197, P0198 EOT sensor

    P0222, P0223 TP sensor

    P0300, P0301, P0302, P0303, P0304 misfire

    P0327, P0328 KS

    P0335 CKP sensor (POC)

    P0340 CMP sensor (PHASE)

    P0420 three way catalyst function

    P0441 EVAP control system

    P0443 EVAP canister purge volume control solenoid valve

    P0444, P0445 EVAP canister purge volume control solenoid valve

    P0447 EVAP canister vent control valve

    P0448 EVAP canister vent control valve

    P0451 EVAP control system pressure sensor

    P0452 EVAP control system pressure sensor

    P0453 EVAP control system pressure sensor

    P0456 EVAP control system

    P0460 fuel level sensor

    P0461 fuel level sensor

    P0462, P0463 fuel level sensor

    P0500 VSS

    P0506 ISC system

    P0507 ISC system

    P050a, P050b, P050e cold start control

    P0520 EOP sensor

    P0524 engine oil pressure

    P0603 ECM power supply

    P0605 ECM

    P0607 ECM

    P0643 sensor power supply

    P0850 PNP switch

    P1078 EVT control position sensor

    P1148 closed loop control

    P117A air fuel ratio

    P1212 TCS communication line

    P1217 engine over temperature

    P1225 TP sensor

    P1226 TP sensor

    P1550 battery current sensor

    P1551, P1552 battery current sensor

    P1553 battery current sensor

    P1554 battery current sensor

    P1564 ASCD steering switch

    P1572 ASCD brake switch

    P1574 ASCD vehicle speed sensor

    P1715 Input speed sensor

    P1720 VSS

    P1805 brake switch

    P2096, P2097 A/F sensor 1

    P2100, P2103 throttle control motor relay

    P2101 electric throttle control function

    P2118 throttle control motor

    P2119 electric throttle control actuator

    P2122, P2123 APP sensor

    P2127, P2128 APP sensor

    P2135 TP sensor

    P2138 APP sensor

    Brake pedal position switch

    Clutch pedal position switch

    Cooling fan

    Electrical load signal

    Fuel injector

    Fuel pump

    Ignition signal

    Malfunction indicator lamp

    On board refueling vapor recovery (ORVR)

    Refrigerant pressure sensor

    Engine control system symptoms

    Normal operating condition

    IDLE SPEED

    Ignition timing

    Evaporative emission system

    EVAP leak check

    Positive crankcase ventilation

    Removal and installation

    Service data and specifications (SDS)

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