If there is idle instability, high or low, or even flameout is a very headache, because the electric injection car is not like carburetor models, adjust the idle screw can be solved.

For common spray vehicles, such as the Use of Delphi electronic spray system, if the above situation occurs, and accompanied by the fault light, it means that the idle control system has a problem, at this time if the fault detector read the fault code, usually will show P0505 fault code.

P0505 fault code means that the difference between the actual idle speed and the target speed exceeds the specified value within the specified time. In layman's terms, the code tells the mechanic that the ECU is unable to get the engine to speed as expected.

Two conditions must be met to report this fault code:

First, the speed difference exceeds the calibration value. For example, the calibration is within 150 revolutions, but the actual deviation from the target is more than 150 revolutions.

The second is to meet the maintenance time. A difference of 150 RPM is not an immediate code, but also to meet the maintenance of a period of time, such as: sustained more than 20 seconds of speed out of tolerance.

If the above two conditions are met, P0505 is stored and displayed by the failure lamp, and can also be read by the detector.

For the primary stage of electronic jet maintenance, when seeing this fault code, especially after you understand the meaning of this fault code, there will often be a direct search for idle valve and replacement of idle valve maintenance method, which is actually the inertia of the carburetor era replacement maintenance thought.

For efi motorcycle maintenance, this method is not desirable, because this fault code is the ECU control speed and compare the final logic judgment and quote us the fault code, not like some of the sensor is through direct judgment signal voltage range, so involved with wider range of components, and therefore can not repair it narrowed down to the idle speed control valve, You need to narrow down the scope step by step to find the fault.

In the inspection, first of all to ensure that oil, electricity, gas, machinery these basic functions to normal, the engine temperature is appropriate, if it is water cooled car, water temperature should be above 70 degrees, to ensure that the engine has a normal working environment, there will not be some puzzling interference, affect the judgment.

At the same time, throttle voltage is also a must check item, and the throttle is in the fully closed idle speed (the voltage value of the fully closed throttle meets the ECU identification requirements, and then idle closed-loop control can be carried out). In general, the sensors are generally fine for further diagnosis.

An initial exception check is usually performed by reading the data stream.

Delphi has a BLM cell in the data stream. If it is 33, it means that ECU has identified the idle condition according to the throttle voltage and starts the idle control program accordingly.

Ye Sheng has idling status symbol, which is YES when the throttle is fully closed.

At ordinary times, teachers can measure the voltage value of all kinds of electronic injection system throttle when it is fully closed, in order to prepare for maintenance to the car can not enter the system, do an idle voltage value reference, generally in the range of a few tenths of a volt to 1 volt.

It should be noted that a slightly thick air-fuel ratio at idle is beneficial to idle stability, while a slightly thin ratio should be noted to have a greater impact on idle speed.

In general, there should be no large deviation between the values of the data stream read by the detector. If there are abnormal values, check the cause first. If the diagnostic instrument cannot enter the efI system, it is necessary to use a multimeter to preliminatively check whether the voltage value of each sensor is abnormal, and MSC super test lamp can also be used to observe whether the sensor and actuator work normally.

The core component of idle control valve is stepper motor. If there is a problem with idle valve, it is most likely that the stepper motor is faulty. It can be repaired by the following methods.

The rotation of stepper motor is realized by changing the polarity of winding A and B. Popular say, be a while south, a while north of the upside down.

In the driving circuit of H bridge, when S1 and S3 are closed at the same time, S2 and S4 are disconnected at the same time. When S2 and S4 are closed, S1 and S3 are disconnected. Thus, the current flows from A→A' and A'→A round trip. The STATOR NS poles of A and B winding change with the direction of the current, and the permanent magnet rotor is pushed and pulled by magnetic rotation step by step. That's how the brief works, and it's a little convoluted, so you can watch it a few more times.

Can do a simple test lamp group to test the quality of the drive tube.

This group of simple test lamp can only be used to detect the drive, because it is a moving part of the stepper motor itself, so in addition to viewing the data flow to judge the good or bad, but also can be removed to add power to feel by hand, this is a real experience.

If you do not want to dismantle, and do not trust its integrity, at the same time you like the wave, oscilloscope to view the working waveform can also.