Solenoid valves. 1.9 TDI PD from VAG Group. Family of diesel engines with injection pump-injector

Solenoid valves

The 1.9-liter TDI engine with the new pump injection system uses four solenoid valves of the pump-injector:

• Valve for pump-injector, cylinder 1 N240;
• Valve for pump-injector, cylinder 2 N241;
• Valve for pump-injector, cylinder 3 N242;
• Valve for pump-injector, cylinder 4 N243.

The solenoid valves of the injector pump are attached to the injector pump by means of a cap nut. The J248 direct fuel injection diesel engine control module regulates the start of the injection points and the number of injections of the injector pump, activating their solenoid valves at the appropriate time.

Start of injection point

As soon as the J248 Direct Fuel Injection Control Module activates the injector solenoid valve, the solenoid presses the solenoid valve down into the valve seat and closes the path from the fuel supply line to the injector high pressure chamber. Then the injection cycle begins.

Number of injections

The number of injections depends on the time during which the solenoid valve is activated. The fuel is injected into the combustion chamber while the solenoid valve of the injector pump is closed.

Consequences of breakage

If the injector pump solenoid valve fails, the engine will not run smoothly and its performance will be reduced. The solenoid valve of the injector pump has a dual safety function. If the valve remains open, no pressure will be generated in the injector pump. If the valve remains closed, the high pressure chamber of the injector pump will no longer fill. In any case, the fuel will get into the cylinders.

Electrical circuit

• J248 Direct Fuel Injection Engine Control Module;
• Valve N240 for pump / nozzle, cylinder 1;
• Valve N241 for pump / injector, cylinder 2;
• Valve N242 for pump / injector, cylinder 3;
• Valve N243 for pump / nozzle, cylinder 4.

Control of the solenoid valve of the pump-injector

The J248 Direct Fuel Injection Engine Control Module controls the electric current that triggers the solenoid valves. This provides feedback to the J248 engine control module with direct fuel injection when injection begins. The J248 Direct Fuel Injection Engine Control Module uses this feedback to control the start of injection periods during subsequent combustion cycles. The start of injection begins when the solenoid valve of the injector pump is activated. The current supplied to the solenoid valve of the injector pump creates a magnetic field. With increasing current, the valve closes; the magnetic coil presses the needle of the solenoid valve into the valve seat. This closes the path from the fuel supply line to the high pressure chamber of the injector pump, and the injection period begins. When the solenoid valve contact with its valve seat, the direct fuel injection diesel engine control module J248 detects a characteristic sign of declining and increasing current flow. This point is called the beginning of the injection period (PPI). This means that the solenoid valve of the nozzle pump is completely closed.

So:

"Start of injection" is the moment of time when the drive current to the solenoid valve of the pump-injector is started;

"Beginning of the injection period (PPI)" is the point in time when the solenoid valve needle comes into contact with the valve seat.

When the solenoid valve is closed, the J248 Direct Fuel Injection Control Module maintains a constant current to keep the valve closed. After the required period of time for fuel supply, the active current is switched off and the solenoid valve opens.

Circuit diagram

Consequences of breakage

Due to the failure of the solenoid valve, the start of injection is determined on the basis of fixed values from the control card. Adjustment becomes impossible and engine performance deteriorates.

Read more about the family of diesel engines with injection pump-injector here .