Study on large idle air volume of new body

The purpose of idle air learning operation is to keep the engine learning speed within the specified range of idle air intake. This operation must be performed after the following situations occur: after each replacement of the electronic throttle control actuator or ECM; Idle speed or ignition timing is out of the specified range. Before learning the idle air volume, the car needs to meet all the following conditions, otherwise even if any of the conditions are not met immediately, the learning operation will be cancelled: the battery voltage is greater than 12.9 V (when the engine is idling); The engine coolant temperature is 70℃ ~105℃; PNP switch is in the ON position; Electrical load switch (air conditioner, headlight, rear window defogger, etc.). ) are turned off (0ff); The steering wheel is in the middle position (straight ahead position); In the parking state; The temperature of the automatic transmission is already at the normal working temperature (driving the car for more than 10min). When doing this kind of learning operation, it is best to use the clock to accurately time; If the accelerator pedal position sensor circuit is faulty, learning cannot be performed. The specific learning steps are as follows (Figure 1).

(1) Perform accelerator pedal release position learning.

(2) Perform throttle closing position learning.

(3) Start the engine to warm up to the normal working temperature.

(4) Confirm that all conditions of idle air flow learning have been met.

(5) Turn the ignition switch to 0FF position and wait for at least 10 second.

(6) Ensure that the accelerator pedal is completely released, then turn the ignition switch to the 0N position and wait for 3 seconds.

(7) Quickly repeat the following operations for 5 times within 7)5s: completely press the accelerator pedal; Loosen the accelerator pedal completely.

(8) After waiting for 7 seconds, fully press the accelerator pedal, and keep this state for about 20 seconds until the MIL stops flashing and then lights up.

(After the MIL lights up, completely release the accelerator pedal for 3 seconds.

(10) Start the engine and let it idle for a period of time.

(1 1) Idle speed exceeds 20 s.

(12) Run the engine at high speed for 2 ~ 3 times to ensure that the idle speed and ignition timing meet the requirements of Table 1.

(13) If the idle speed and ignition timing are not in the range listed in table 1, it means that the learning of idle air volume cannot be successfully completed. Please follow the following diagnostic steps to find out the problem.

1) Check that the throttle valve is completely closed;

2) check the PCV valve;

3) Check whether there is air leakage downstream of the throttle:

4) If there are no problems in the above three inspections, you need to pay attention to the engine components and their installation, and check and eliminate the cause of the failure;

5) If the engine flameout and idle speed are abnormal after starting, it is necessary to eliminate the cause of the failure and relearn the idle air volume.