郎咸平沈阳演讲

发动机电脑系统的故障诊断

The engine computer system fault diagnosis

一基本检查A basic inspection

在进行所有的故障诊断前，必须先进行基本检查，因为有些基本故障，通过DME电脑自诊断系统和油门电脑，是自检不出来的，甚至有时还会对自诊断和故障存储功能起干扰作用。

Before all the fault diagnosis, we must carry on the basic test, because there is some basic troubleshooting, DME from diagnosis system by computer and throttle computer is not to come out, and even sometimes it may make some interference for the diagnosis and fault memory function.

例如电瓶电压过低会引起电脑储存器的错误设定或没有设定就进入“失效保护”状态，而且对一个正常运转的发动机进行检测也会导致故障码的储存，这可能是由于模拟操作或断路等原因引起的，

另一方面，系统中存储的故障码会随着电脑的电源中断而被清除掉，因此，在中断电源或检测前，应先读出所存储的故障码。这样就会确保技术人员能正确区分真正的故障和模拟的故障。

For example, battery voltage is too low will cause the computer memory error setting or enter the "failure protection" condition without setting, but also to a normal operation of the engine for testing could also lead to a fault code storage, this may be due to the simulation operation or open circuit.

On the other hand, the system stored in the fault code with the computer power interrupted and will be cleaned away, therefore, before interrupt power supply or detection, we should read stored fault code firstly. This will ensure that the technical personnel can distinguish between the real fault and simulation of the fault.

检测完成后，DME和EML电脑存储器内的故障码应被清除掉，在修理或更换零配件前，应以如下步骤进行基本检查：

After testing is done, computer memory fault in code from DME and EML should be cleared away, before the repair or replacing parts, should have basic check with the following steps:

1,核实车主反应的情况V erify the reaction from owner

技术人员尽可能亲自去核实车主所反映的情况，经亲身核实故障后，就不会去修理那些不存在的故障了。As far as possible to verify the condition reflected by the owner, after checking fault in person, they won't go to repair those not having fault.

2,故障的核实The verification of failure

对当今装备有电脑控制的高级轿车，因其电路复杂，在维修中应尽可能采用专门的仪器以全新的方法去进行修理，必要时技术员应将该系统的工作情况与正常系统的工作情况作比较，还要将有故障的汽车与正常的汽车作比较。

For today's luxury car equipped with computer control, because of its circuit complex, we should adopt the special instrument as far as possible as a whole new way to repair for maintenance, if necessarily, the technician should give the working conditions of system and normal system work comparison, meanwhile, should make the fault of the car and a normal car compare.

3,以前的修理或改装记录The former repair or modified record

汽车的维修记录可以对一些异常的现象作解释，这些异常现象可能会困扰正常的诊断思路，使用不合格的配件，进行非正式的修理或改装都有可能会对那些看似不相关的系统其重要影响作用。

The maintenance records of cars can explain some abnormal phenomenon, the abnormal phenomenon may trouble the diagnosis of normal mentality, using unqualified parts, having unofficial repair or modification, all of them can produce the great impact on some unrelated systems.

4,电瓶的充电状态Charging the battery

充电不足的电瓶会影响DME电脑及其相关的元件。

Charging the insufficient battery will affect DME computer and its related components.

5,电瓶正极电线的完整性Battery positive the integrity of the wire

所有电瓶正极的连接状态都应完好，以确保电子系统的工作正常。

All battery positive connection should be in good condition, to ensure that the electronic system works normally.

6,熔丝链的完整性The integrity of fuse chain

熔丝链防止电气元件及配线受到损坏，这些熔丝链及连接应不允许有动态电阻存在，动态电阻只能用测电压降的方法来检测到。

Fuse is used to protect electrical components and the damaged wiring, the fuse and connections do not allow to have the dynamic resistance exists, dynamic resistance can only use the method of measuring voltage drop to detect.

7,负极搭铁连接Negative ground connection

由于所有的电路形成闭合回路，因此还必须检查所有的负极连接，核实他们是否处于良好的状态下，因为不良的共用搭铁点会引起不相关系统间的相互影响。

Because all of the circuits form closed loop, therefore we must check all negative connections, to verify whether they are in good condition, because bad ground points can cause not related systems interactions.

8,电线的连接The connection of wire

当连接发动机或变速箱的金属导线变色或过热时，就应彻底检查以下所有搭铁连接点。

When the discoloration or overheating of connecting engine or gearbox metal wires, we should thoroughly check all ground connection.

9,电源继电器Power relay

油泵和DME主继电器及其连接装置的连接处不良时，将不会在DME的故障存储器中存储故障码。

The joint of the oil pump and DME main relay and the link device is bad, will not store fault code in the fault memory storage.

10,曲轴和凸轮轴位置传感器The crankshaft and the camshaft position sensor.

传感器的检查应从静态和动态俩方面，必须确保传感器的正确安装并处于良好的状态。

Inspection of the sensor from static and dynamic aspects, must ensure that the corrected installment of sensor and the senor should be in good condition.

11,高压线圈和次级元件配线High pressure coil and subprime components wiring

12,燃油压力Fuel pressure

13,气门间隙及火花塞V alve clearance and spark plugs

二自我诊断（查找故障）Self diagnosis (finding fault)

1 确定故障步骤Ensure the fault steps

(1)诊断系统快速检测The diagnosis system fast detection

系统的快速检测和查询功能会检测所有具有存储故障码能力的控制系统。并核实其他相关系统是否都在正确运行。

The rapid detection system and the function of query can test the control system having the ability to store fault code. And check whether all other related systems are in the correct operation.

(2)故障码的查询Fault code query

系统快速诊断期间，需对含有故障码的系统进一步访问。如同时有多个代码，要查询各代码之间的关系，并确定故障的主要原因。

During the rapid diagnosis of system, need to have a further access for containing fault code system. If there are several code, need to inquire the relationship between each code and find out the main reason.

(3)故障码检测Fault code detection

检测说明用于解释和补充自我诊断系统或诊断仪引出的故障信息。

Testing instructions used to explain and add self diagnosis system or the fault information came out from diagnostic instrument.

2 状态监控和元件监控Condition monitoring and control components

(1)状态监控（数据流）Condition monitoring (data flow)

故障码存储功能分别监控输出和输入的工作状态。这样可以显示当前值或工作状况。

Fault code storage function can separately monitor output and input working condition. This can display the current value or work conditions.

(2)元件触发Components triggered

可将诊断仪器与DME电脑相连来触发各元件。

Putting the diagnosis instrument and DME computer connect to trigger the components.

3 参数Parameters

各元件都有各自的参数，可将实际参数和所测值作比较。

Each element has its own parameters, give the actual parameters and the value measured compare.

三读取、记录所显示的故障码Read, record fault code shows

四清除故障码Clear fault code

1断开点火开关，拆下DME Interrupt the ignition switch, remove the DME.

2断开电瓶Disconnect the battery .

3排除故障后，启动发动机60次After removing fault, start the engine 60 times.

4使用宝马检测仪Use BMW detector.

DME

1 DME功能简述DME function briefly reviewed

DME对燃油喷射和点火系统提供精确控制，以确保达到最佳性能和满足严格的排放标准。

DME provides accurate control for fuel injection and ignition system, so as to ensure the best performance and meet stringent emission standard.

2工作原理Working principle

各种传感器和其他相关系统（如空调、自动变速器等）向DME电脑提供工作信号，DME电脑处理这些输入信号，发出控制信号以控制喷油器喷油的脉冲宽度，修正点火正时，并对其他有关系系统和元件输出控制信号。All kinds of sensors and other related system (such as air condition, automatic transmission, etc) provide work signals for DME computer, DME computer can deal with these input signals and send control signals to control the pulse width injector, fix ignition timing, and output control signal for the relevant components and systems.

ABS

防抱死制动系统（ABS）由ABS电脑、液压装置、车轮转速传感器、制动液压管路及电气配件线等组成。ABS is made up of computer, hydraulic device, ABS wheel speed sensors, braking hydraulic pipeline and electrical fittings line etc.

ABS电脑是一个微处理器，它主要有三项功能：

ABS computer is a microprocessor, and it mainly has three functions:

1 输入信号的计算The calculation of input signals.

2 输出信号控制The output signal control.

3 自诊断功能 Self diagnosis function.

仪表板上的ABS指示灯用来指示防抱死系统的工作状态。当点火开关转至位置后，ABS指示灯点亮，发动机启动后应随之熄灭。如果指示灯没有熄灭或是在行车途中亮起，则表明ABS系统有故障，必须进行检修，此时防抱死制动系统只具有普通制动系统的功能，防抱死功能不在起作用。

The purpose of ABS indicator light from dashboard is to indicate the working state of the antilock braking system. When the ignition switch turns to position, ABS indicator lights, it should is extinguished after the engine starts. If the light does not put out or indicator lights on the driving way, which means the ABS system has fault and needs for maintenance, the ABS antilock braking system only has common functions at this moment, antilock braking function is ineffective.

安全气囊Airbag

1 系统检测System testing

如果存储了故障码，安全气囊系统将解除工作状态，直到用外部诊断设备从存储器中清除故障码后，系统才会恢复工作。但是诊断设备仍会继续监控系统。如果在进行诊断时，故障仍然存在，表明该故障为长期性故障。如故障不复存在，则故障类型转为间歇性故障，故障码仍保持在安全气囊电脑的存储器内。

If the fault code is stored, the airbag system will remove working state. The system may go back to work until the fault code is eliminated from memory by the external diagnostic equipment. But diagnostic equipment will continue to monitor the system. If the fault still exists during the diagnosis, which means it is a long-term fault. If the breakdown no longer exists, the type of fault is converted into intermittent fault and the fault code still is remained within the memory of the computer of the airbag.

2 只能用MODIC系统或与宝马诊断系统相兼容的检测仪来读取故障码。

Only use the compatible detector of MODIC or BMW diagnosis system to read fault code.