Generally, we should make some basic settings before we diagnosis the throttle valve using Launch X431. But why should we do so? You should find that if the throttle valve gets dirty, the opening degree of it will become larger when the motor idles after reading the data stream. It because that if the throttle valve gets dirty air amount inhaled will be smaller under the same opening degree which cannot ensure the rated speed of the motor,so, the opening degree of the throttle valve will become larger. On the contrary, it will be smaller if you clear the throttle valve. All these show that electronic control unit has a function of learning which can not only check out change of the component parameters but also adapt to this change. However, how to know the initial parameters of the electronic control unit?
That just requires some basic settings. Before we do that, if the electronic control unit receives a voltage signal from the idling position of the throttle valve without knowing its opening degree, it shows that the electronic control unit don't know the smallest idling position and the largest idling position and other basic parameters of the throttle valve. On the contrary, if it knows those all then it knows the voltage range of potentiometer. Be further, it will know the characteristics of potentiometer throttle valve's potentiometer if the electronic control unit get one or more voltage values between the largest value and the smallest value. So, the electronic control unit may ensure the opening of the throttle valve after it getting one voltage signal from any idling position. Basic settings are to make the electronic control unit know basic characteristics and basic parameters of the throttle valve. Thus, it will automatically adjust the movement between itself and the throttle valve in the future.
Passages for basic settings
The basic setting is the artificial creation of a specific initial state, which is that force the electronic control unit to do some basic settings using a fault diagnostic. It controlled by the electronic control and cannot be interfered artificially. Well, why the passages differ when do basic settings with same instrument? It because that basic settings depend on instruments while the passages depend on software used. Take Audi as example:
Car Models Electronic control system Passage
Audi 200/V6 BOSCH 001
Audi 200/1.8T BOSCH 098
Component movements of basic settings
Careful repairmen may have heard the da da voice from the throttle valve and seen it was in jitter during basic settings. Which are the actions of the throttle valve under the driving of the idling motor inside it as bellow: From the initial position to the minimum position, and then turn from the minimum position to the maximum position, and finally back to the initial position. Meanwhile, the electronic control unit settled down the maximum, minimum, and three equal positions between the maximum and minimum positions. Thus, the electronic control unit has identified the characteristics of the throttle valve.
Under what circumstances should we do the basic settings
From the above principle analysis, we need do some some basic settings if there are some factors that affect the coordination between the electronic control unit and the throttle body.
The electronic control unit hasn't saved the characteristics of the throttle body after changed to a new one. If so, we do.
The electronic control unit has lost its memory on the the characteristics of the throttle body after an accident power failure. Thus, we do.
You have changed a new throttle body. If so, we do.
There are some factors that may affect the coordination between the electronic control unit and the throttle body and the control to idling after replacing or dismantling the inlet. If so, we do.
After cleaning the throttle body, intake air amount and idling control features changed under the same opening degree of the throttle valve although the characteristics of the idling throttle valve's potentiometer. If so, we do.
Consequences without basic settings
It will be uncoordinated the work between electronic control unit and the idling speed control devices without basic setting after repairing or replacing components above. Which shows that idling control will be inaccurate and unstable. But it is temporary for the electronic control unit having functions of learning and adapting automatically. However, the process is not so rapid and accurate as basic settings . For some certain cars not only need basic settings but also need to clear the original data learned after repairing or replacing components above. It depends on softwares of cars.
Take Jetta as an example, if we do some basic settings only the idling speed will be higher than the real value after cleaning throttle valve of the avant-garde car. This because that electronic control unit still remember the opening degree of the original throttle valve.
Step of basic settings
Controller Area Network (CAN) is a standard bus invented for connected devices of cars specially. It established for car markets initially(as car bus) but now it has been used for transformation form high-speed network to low cost diverse harness. Under CAN mode, all the sensors and control units should be connected to a main line signal sharing. CAN system will form the CSMA/CA according to the certain rules. There are two common message formats bellow:
Standard format: 11 bits identifier.
Expansion format: 29 bits identifier, defined in CAN protocol version 2.0.
To accept these two formats of CAN, executive standard must accept the standard format and extended format and expand more formats.
After know the significance of basic settings we should know how to do it. In fact, it's very easy and these are usual steps bellow(taking Audi as an example):
Turn on ignition switch (Do not start the engine ).
Into the 'Engine System', read and clear certain codes.
Select function 'System Basic Adjustment' enter the passage number: 001: Audi 200.
Press key 'OK' and see the data showed data in region 4. If it shows 'The computer adaptive normally', it means that the match is successful then you may exist.