There is no fault code when Buick LaCrosse accelerates.

Check that there is nothing wrong with the oxygen sensor circuit, and then check the coolant temperature sensor, throttle opening sensor, air temperature sensor and intake vacuum pressure sensor (air temperature sensor and intake vacuum sensor are integrated). It is found that the resistance value of the air temperature sensor seems to be too high, the resistance values of other sensors are normal, and the circuit power supply voltage is also normal. Therefore, the resistance of each sensor is measured, and it is found that the resistance of other sensors varies widely except the resistance of the air temperature sensor. With a new temperature sensor, the engine starts smoothly, the black smoke disappears and the idle speed is stable. But when accelerating rapidly, the engine is still slow and weak. After removing the spark plug, it was found that there was a large amount of carbon deposit. After changing four spark plugs, the rapid acceleration did not improve, and the ignition timing was adjusted, but it still did not improve.

Check the high-voltage line, cylinder line, high-voltage coil, distributor cover and distributor head, and there is nothing abnormal, so the analysis problem may be the oil supply system. It is found that there are many impurities in gasoline, and there are dirt on the bottom of oil tank and the filter screen of oil pump. After cleaning, the gasoline filter was replaced, and the measured oil supply pressure was normal. The four fuel injectors of the engine are cleaned, the idle speed is stable, and the sudden acceleration is stable. The oxygen sensor of the original car was changed back, and the test run was normal, indicating that there was no problem with the oxygen sensor of the original car.