In 2002, I bought a 2-valve Jetta with a new throttle, nozzle, oil pump and spark plug, and now the fuel consumption is 14. Why is it so expensive?

The first thing to check is whether the pressure of the fuel system is correct 240kpa.

Spark plug model: Bosch F8 DCOR.

Whether the fuel return pipe of the fuel system is unblocked and whether there is throttling phenomenon.

The condition of the fuel pressure regulator. Is the hose leaking?

Enter the engine data stream to see whether the long-term and short-term fuel correction values are normal; Whether the signal voltage of oxygen sensor is normal.

Is the injector leaking? Is the model of the new injector correct?

Whether the performance of knock sensor is normal.

Service delay of braking system.