Is it normal that the fuel consumption is always 0.5 to 0.6 at idle speed?

This is normal if the engine idling only jumps in the range of about 50 rpm. If the idle speed fluctuates greatly, check the idle speed control system, which is mainly composed of sensors, signal control switches, electronic controllers and idle speed control valves. The ECU controls the engine to keep in the best working state according to the input signals of each sensor. After this fault occurs, it is mainly to check whether the input signals of each sensor to ECU are normal, and then check the working condition of the actuator. Then, check the carbon deposition of throttle and idle valve. If there is carbon deposit in these parts, it will also cause the engine to idle unsteadily.