Excessive fuel consumption
Engine fuel consumption fault:
Excessive engine fuel consumption refers to its fuel consumption exceeding the specified standard value per 100 kilometers. Excessive fuel consumption results in poor engine economy. There are many factors that affect engine fuel consumption, including factors related to engine technology and chassis technology.
1. Fault phenomenon: The engine consumes too much fuel.
2. Common causes of malfunctions
1) The coolant temperature sensor is malfunctioning.
2) The air flow meter or intake pressure sensor is malfunctioning.
3) The throttle position sensor is malfunctioning.
4) The fuel pressure is too high.
5) Cold start fuel injector oil leakage or cold start control malfunction.
6) The fuel injector is leaking oil.
7) Oxygen sensor failure.
8) Ignition system malfunction.
9) Engine mechanical component failure (low cylinder pressure, etc.).
10) The valve timing is incorrect.
11) ECU and connector malfunction.
3. Fault diagnosis and troubleshooting
1) The resistance value of the coolant temperature sensor at different temperatures should meet the standard. A high resistance can cause the computer to mistakenly believe that the engine is in a low temperature state, leading to cold car enrichment control and increased fuel consumption. You can also use a computer decoder to detect and compare the coolant temperature value displayed by the detector from the coolant temperature sensor to the computer with the actual engine coolant temperature. If there is a difference, it indicates that the coolant temperature sensor is faulty and should be replaced.
2) Detect the air flow meter or intake pressure sensor, and its value should meet the standard. The error of the air flow meter or intake pressure sensor will directly affect the fuel injection quantity. If there are any abnormalities in the test results, the air flow meter or intake pressure sensor should be replaced.
3) Check the throttle position sensor. When the throttle valve is in a medium to small opening position, the full load switch should be disconnected. If the full load switch is always closed or closed too early, it will cause the computer to continuously or prematurely perform full load enrichment, thereby increasing fuel consumption.
4) Measure fuel pressure. The fuel pressure at idle should be around 250kPa. As the throttle valve opens, the fuel pressure should gradually increase. The fuel pressure when the throttle is fully open is about 300kPa. If the fuel pressure can change with the throttle opening, but the pressure remains high, it indicates that the oil pressure regulator is faulty and should be replaced. If the fuel pressure cannot change with the throttle valve opening and remains around 300kPa, it indicates that the vacuum hose of the oil pressure regulator is broken or detached, or there is a malfunction in the fuel pressure regulation control solenoid valve, and the vacuum degree of the intake pipe does not act on the vacuum diaphragm chamber of the oil pressure regulator, resulting in high oil pressure. In this regard, the hose or solenoid valve should be replaced. If the fuel pressure is too high and exceeds 400kPa, it indicates that the return pipe is blocked or the oil pressure regulator is faulty. The return pipe should be checked or the oil pressure regulator should be replaced.
5) Check the ignition high voltage, energy, and ignition timing.
6) Check if the cold start fuel injection control is normal. Connect a voltmeter or test light to the harness plug of the cold start fuel injector and check if the duration of the cold start fuel injector operation during engine starting meets the standard value. If the working time is too long or continues to work after starting, it indicates that the control of the cold start fuel injector is abnormal. The cold start temperature switch and control circuit should be checked.
7) Disassemble the fuel injectors and check for any oil leaks in each injector. If there is any abnormality, the fuel injector should be cleaned or replaced.
8) Check for mechanical faults in the engine (cylinder pressure, valve stagnation or leakage, camshaft wear, valve timing, valve clearance, valve sealing, etc.), check for blockages in the exhaust system, and check the operation of the cooling system thermostat.