JAC Ling Jun V6 always lights the exhaust pipe heating indicator light and then idling up. What's the matter?

Fault analysis When the idle contact is disconnected, ECU determines that the engine is in a partial load state. At this time, ECU determines the fuel injection quantity and time according to the air flow sensor, crankshaft position and speed signal. At this time, the engine is idling, and the intake air is less, which leads to the mixture being too rich and the speed increasing.

When the ECU receives the signal that the mixture is too rich from the oxygen sensor, it will reduce the fuel injection and increase the opening of the idle control valve, which will lead to the mixture being too lean and slow down the vehicle speed. When the ECU receives the signal that the mixture fed back by the oxygen sensor is too lean, it will increase the fuel injection and reduce the opening of the idle control valve to make the mixture too rich, thus increasing the speed.

This repetition makes the idle speed of the engine unstable. When idling, turning on the air conditioner, steering wheel and headlights will increase the load of the engine. In order to prevent the engine from stalling due to the increase of load, ECU will increase the fuel supply to maintain the balanced operation of the engine. When the idle contact is disconnected, ECU thinks that the engine is not in idle state and will not increase the fuel supply, so the speed will not increase.

Diagnostic method: Turn on the air conditioner and turn the steering wheel when idling. If the engine idle speed does not increase, it is proved that the idle speed switch is not closed. Troubleshooting Adjust or replace the throttle position sensor.