ECD-V5 Injection Pump System

ECD-V5
Injection Pump System

NOTE: Some of the components of the ECD-V5 injection pump system are very similar in design and operation to those of the NP-VE4 injection pump system. Therefore this lesson only describes the components which are new or operate in a different way to those in the NP-VE4 injection pump system.

Intake system

·           The construction and operation of the intake system is essentially carried over from that of the NP-VE4 injection pump system except for the following:

-        Mass air flow sensor has been eliminated (only Euro 2 vehicles)

-        Turbocharger with variable geometry turbine has been adopted (only Euro 3 vehicles)

-        Variable swirl control valve has been adopted (only Euro 3 vehicles)

Parts location

Intake system (continued)

System overview

Turbocharger

·           Mazda vehicles with RF-T engine and Euro 3 emission standard feature a turbocharger with VGT (Variable Geometry Turbine), which controls the boost pressure by adjusting guide blades. The blades are located in the turbine housing and are driven by a vacuum actuator, resulting in an increased power output and a reduced fuel consumption.

·           The guide blades vary the cross-section in front of the turbine and thus the passages that duct the exhaust gas to the turbine. The position of the guide blades is controlled by the PCM, which activates the VBC (Variable Boost Control) solenoid valve via a duty signal. As a result, the boost pressure remains approximately the same over the entire engine speed range.

Turbocharger (continued)

·           At low engine speeds the PCM controls the VBC solenoid valve with a large duty cycle, so that vacuum is applied to the vacuum actuator. Due to this the guide blades move in the closing direction and the passages that duct the exhaust gas to the turbine become narrow. Thus the exhaust gas stream impinges with a high velocity and a small angle on the turbine, resulting in a high boost pressure.

Turbocharger (continued)

·           At high engine speeds the PCM controls the VBC solenoid valve with a small duty cycle, so that atmosphere pressure is applied to the vacuum actuator. Due to this the guide blades move in the opening direction and the passages that duct the exhaust gas to the turbine become wide. Thus the exhaust gas stream impinges with a low velocity and a large angle on the turbine, resulting in a low boost pressure.

NOTE: If the VBC system fails, the blades adopt in a parked position again in which only a minimal boost pressure is produced.

·           The PCM controls the VBC solenoid valve by a duty signal between 0…12 V.

Turbocharger (continued)

Diagnostics

·           The turbocharger can be checked as following:

-        Monitoring the boost pressure via the PID MAP (Press/Volt)

-        Checking turbocharger (see NP-VE4 injection pump system)

-        Checking boost pressure (see NP-VE4 injection pump system)

-        Monitoring/Activating the blade adjustment via the PID VBCV# (Per)

-        Checking the voltage signal at the VBC solenoid valve

-        Checking blade adjustment

Checking blade adjustment

·           Connect a hand-operated vacuum pump to the VBC actuator and apply vacuum. Check, whether the adjusting linkage moves easily, and returns to the parked position when the system is vented.

NOTE: The blade adjustment system is a fixed part of a turbocharger. As turbochargers usually cannot be repaired with the means available in workshops, they must be changed complete.

Variable swirl control valve

·           Mazda vehicles with RF-T engine and Euro 3 emission standard are equipped with VSC (Variable Swirl Control) valves in the intake manifold, reducing the exhaust emissions at low engine speed. The VSC valves are driven by a vacuum actuator and vary the cross-section of the manifold. Therefore the intake manifold features two inlet ports per each cylinder. The swirl port induces the intake air tangentially into the combustion chamber, while the charge port induces it vertically.

·           The shutter valves close or open the charge ports, influencing the passages that duct the intake air into the cylinder. The position of the shutter valves is controlled by the PCM, which activates the VSC solenoid valve by an ON/OFF signal.

Variable swirl control valve (continued)

·           At an engine speed below 2300 min-1 the PCM energizes the VSC solenoid valve, so that vacuum is applied to the vacuum actuator. Due to this the shutter valves close the charge ports, decreasing the cross-section of the intake manifold. Thus the intake air enters the cylinder only via the swirl port, creating a high air flow speed and a strong swirl. This improves the mixture of the injected fuel with the air and hence the combustion.

Variable swirl control valve (continued)