The idle speed of Lexus 350 suddenly increased during driving.

There may be several reasons for the sudden increase of idle speed without stepping on the accelerator while driving: an automatic car automatically downshifts. When the automatic transmission car is in D gear, its computer program sets the upshift program. After the downshift operation, in order to maintain speed consistency, the idle speed naturally increases. This is also normal. When a manual car goes downhill, the speed becomes faster, and the movement of the car body is transmitted to the car engine to prevent the engine from rising. When the clutch is disengaged, the idle speed of the car will be improved to varying degrees, and when the air conditioner is turned on, the idle speed will be slightly improved. This is a normal phenomenon. Do not rule out car failure or other reasons, such as dirty throttle, excessive carbon deposition, gearbox failure or poor oil. If this is an abnormal reason, you should go to a professional garage for inspection and maintenance.

Subsequently, the maintenance personnel connected the detector and began to read the fault code. As a result, the fault code about the abnormal circuit of the throttle sensor was obtained. By consulting the data, it is known that the fault can be roughly solved by replacing the throttle body assembly. After that, the maintenance personnel read the corresponding system parameter data when the system diagnoses the fault code. Through inspection, it is known that the data parameters of the engine are basically normal at this time, but the temperature of the transmission lubricating oil is low.

After the maintenance personnel grasped the above information, they first inspected the throttle body circuit in detail, but found no abnormality. Then the maintenance personnel took off the throttle and cleaned it, but the fault didn't ease at all, and the oil temperature of the transmission even became lower, so the maintenance personnel re-established the direction and focused on the engine and transmission circuit.