哈密市福特新蒙迪欧电信宽带维修联系方式0。一辆行驶里程约9万km、配备2.0T发动机，搭载6F35自动变速器的长安福特新蒙迪欧轿车。（哈密福特新蒙迪电信宽带维修）用户反映：该车在行驶过程中出现发动机偶发性熄火的故障，但是熄火后均能正常起动。（哈密福特新蒙迪电信宽带维修）同时，用户还反应车辆近段时间动力不足。（哈密福特新蒙迪电信宽带维修）
检查分析：维修人员接车后首先对车辆进行了一些基本检查，未发现明显的异常。（哈密福特新蒙迪电信宽带维修）用专用诊断仪IDS对车辆进行自诊断，没有任何发动机相关的故障码记录。（哈密福特新蒙迪电信宽带维修）使用IDS读取发动机的相关数据流，显示长期燃油修正为8.59%，低压侧燃油压力为750 kPa，压力值明显比目标值要大。（哈密福特新蒙迪电信宽带维修）同时发现怠速工况时燃油泵控制单元的占空比为21.33%，远低于正常车辆的35％左右（图1）。（哈密福特新蒙迪电信宽带维修）而在正常情况下，当占空比为35％时，低压侧的燃油压力应在660 kPa左右。（哈密福特新蒙迪电信宽带维修）其他的数据没有发现明显的异常。（哈密福特新蒙迪电信宽带维修）
燃油泵控制单元的占空比低于正常值，但油压反而高于正常油压，这与常理不符。（哈密福特新蒙迪电信宽带维修）从读取到的数据分析，初步认为可能是发动机控制单元（PCM）接收到了错误的低压燃油压力信号（FLP信号）。（哈密福特新蒙迪电信宽带维修）PCM误认为低压侧燃油压力已经达到750 kPa，高于目标压力，于是持续向燃油泵控制单元发出减少供油量的信号，因此数据流中燃油泵控制单元的占空比信号（FP信号）才会始终低于35％的正常值。（哈密福特新蒙迪电信宽带维修）
为了验证分析结果是否正确，连接燃油压力表测量低压侧的实际燃油压力。（哈密福特新蒙迪电信宽带维修）在发动机怠速工况下，数据流FLP信号显示为750 kPa时，从压力表测得的实际燃油压力只有250 kPa。（哈密福特新蒙迪电信宽带维修）关闭发动机，打开点火开关到ON挡，通过燃油压力表将低压侧燃油压力释放到0 kPa时，发动机数据流显示FLP信号依然为750 kPa，显然PCM接收到的低压侧燃油压力信号是错误的。（哈密福特新蒙迪电信宽带维修）
从上述控制单元数据流以及实测的燃油管路压力数据，可以确认PCM接收到了错误的低压燃油压力信号。（哈密福特新蒙迪电信宽带维修）导致信号错误的原因可能有以下2种：燃油压力传感器本身故障或相关线路故障；PCM内部电路故障。（哈密福特新蒙迪电信宽带维修）
根据低压侧燃油压力传感器相关电路图排查线路（图2）。（哈密福特新蒙迪电信宽带维修）打开点火开关，从低压燃油压力传感器的C1691插接器1号端子处测量的信号电压为4.8V，与数据流显示的基本对应，测量C1691插接器3号端子的参考电压为5.0V、3号端子的搭铁线路也正常。（哈密福特新蒙迪电信宽带维修）断开传感器的C1691插接器和PCM的C1381 B插接器，检查信号线，未发现与其他线路有短路现象。（哈密福特新蒙迪电信宽带维修）至此可以判断是压力传感器本身故障。（哈密福特新蒙迪电信宽带维修）
故障排除：更换遮阳帘控制单元并进行基本设置，试车故障排除。（哈密福特新蒙迪电信宽带维修）
Beihai Ford New Mondeo car maintenance contact 0. A new Mondeo car of Changan Ford with a mileage of 90000 km, a 2.0T engine and a 6f35 automatic transmission. (Beihai Ford New Mondi car maintenance) the user reported that the car had occasional engine stalling during driving, but it could start normally after stalling. (Beihai Ford New Mondi car maintenance) at the same time, users also reported that the vehicle lacks power in recent period. (Beihai Ford New Mondi car maintenance)
Inspection and analysis: after receiving the vehicle, the maintenance personnel first carried out some basic inspections on the vehicle and found no obvious abnormality. (Beihai Ford New Mondi automobile maintenance) uses the special diagnostic instrument IDs to carry out self diagnosis on the vehicle, without any engine related fault code records. (Beihai Ford New Mondi automobile maintenance) used IDs to read the relevant data flow of the engine, showing that the long-term fuel correction was 8.59%, the low-pressure side fuel pressure was 750 kPa, and the pressure value was significantly higher than the target value. (Beihai Ford New Mondi car maintenance) at the same time, it is found that the duty cycle of fuel pump control unit is 21.33% under idle condition, which is far lower than about 35% of normal vehicles (Figure 1). (Beihai Ford New Mondi car maintenance) under normal circumstances, when the duty cycle is 35%, the fuel pressure on the low-pressure side should be around 660 kPa. (Beihai Ford New Mondi car maintenance) other data did not find obvious abnormalities. (Beihai Ford New Mondi car maintenance)
The duty cycle of the fuel pump control unit is lower than the normal value, but the oil pressure is higher than the normal oil pressure, which is not consistent with the general principle. (Beihai Ford New Mondi car maintenance) based on the data analysis, it is preliminarily believed that the engine control unit (PCM) may have received the wrong low pressure fuel pressure signal (FLP signal). (Beihai Ford New Mondi automobile maintenance) PCM mistakenly believes that the fuel pressure on the low-pressure side has reached 750 kPa, which is higher than the target pressure, so it continuously sends a signal to the fuel pump control unit to reduce the fuel supply quantity, so the duty cycle signal (FP signal) of the fuel pump control unit in the data flow will always be lower than the normal value of 35%. (Beihai Ford New Mondi car maintenance)
In order to verify whether the analysis results are correct, connect the fuel pressure gauge to measure the actual fuel pressure on the low-pressure side. (Beihai Ford New Mondi automobile maintenance) when the data flow FLP signal is displayed as 750 kPa under the engine idling condition, the actual fuel pressure measured from the pressure gauge is only 250 kPa. (Beihai Ford New Mondi car maintenance) turn off the engine, turn on the ignition switch to on gear, and release the fuel pressure at the low-pressure side to 0 kPa through the fuel pressure gauge, the engine data flow shows that the FLP signal is still 750 kPa, obviously the fuel pressure signal at the low-pressure side received by PCM is wrong. (Beihai Ford New Mondi car maintenance)
From the data flow of the above control unit and the measured fuel line pressure data, it can be confirmed that the PCM has received the wrong low pressure fuel pressure signal. (Beihai Ford New Mondi car repair) there are two possible reasons for signal error: the fuel pressure sensor itself or related circuit fault; the PCM internal circuit fault. (Beihai Ford New Mondi car maintenance)
Check the circuit according to the circuit diagram of the fuel pressure sensor at the low pressure side (Fig. 2). (Beihai Ford New Mondi automobile maintenance) turn on the ignition switch, and the signal voltage measured from terminal 1 of c1691 connector of low-pressure fuel pressure sensor is 4.8V, which basically corresponds to the data flow display. The grounding circuit of terminal 3 of c1691 connector measured with the reference voltage of 5.0V is also normal. (Beihai Ford New Mondi automobile maintenance) disconnect the c1691 connector of the sensor and the c1381b connector of the PCM, check the signal wire, and no short circuit with other wires is found. (Beihai Ford New Mondi car maintenance) so far, it can be judged that the pressure sensor itself is faulty. (Beihai Ford New Mondi car maintenance)
Troubleshooting: replace the sunshade control unit and make basic settings, and troubleshoot the test run. (Beihai Ford New Mondi car maintenance)
