1) Measure the coolant temperature sensor, the resistance value at different temperatures should meet the standard. If the resistance is too large, the computer will mistake the engine for a low temperature condition, so that the cold car enrichment control will increase the fuel consumption. It can also be detected by a computer decoder, and the coolant temperature value transmitted to the computer by the coolant temperature sensor displayed by the detector is compared with the actual coolant temperature of the engine. If there is a difference, the coolant temperature sensor is faulty and should be replaced.
2) Detect air flow meter or intake pressure sensor, the value should meet the standard. Errors in the air flow meter or intake pressure sensor directly affect the amount of fuel injected. If there is any abnormality in the test results, the air flow meter or the intake pressure sensor should be replaced.
3) Check the throttle position sensor. When the throttle is at a small opening, the full load switch should be disconnected. If the full load switch is always closed or closed too early, the computer will always or prematurely full load enrichment, thus increasing fuel consumption.
4) Measure fuel pressure. The fuel pressure at idle should be around 250 kPa. As the throttle opens, the fuel pressure should gradually increase. The fuel pressure when the throttle is fully open is about 300 kPa. If the fuel pressure can change with the throttle opening change, but the pressure is always high, the oil pressure regulator is faulty and should be replaced. If the fuel pressure cannot be changed with the throttle opening change, and it is always maintained at about 300 kPa, the vacuum hose of the oil pressure regulator is broken or detached, or the fuel pressure control solenoid valve is faulty, and the vacuum of the intake pipe is not affected. The oil pressure chamber of the oil pressure regulator causes the oil pressure to be too high. In this case, the hose or solenoid valve should be replaced. If the fuel pressure is too high, it is more than 400kPa, indicating that the return pipe is blocked or the oil pressure regulator is faulty. The return pipe should be tested or the oil pressure regulator should be replaced.
5) Check ignition high voltage and energy, ignition timing.
6) Check if the cold start fuel injection control is normal. Connect the voltmeter or test light to the cold start injector harness connector and check that the duration of the cold start injector operation at engine start meets the standard value. If the working time is too long or has been working after starting, it indicates that the cold start injector is out of control, and the cold start temperature switch and control circuit should be checked.
7) Disassemble the injector and check each injector for oil leakage. If there is an abnormality, the injector should be cleaned or replaced.
8) Check engine mechanical failure (cylinder pressure, valve stop or leakage, camshaft surface wear, valve timing, valve clearance, valve sealing, etc.), check whether the exhaust system is blocked, and the cooling system thermostat works.