Is the braking effect of Dongfeng Citroen Triumph car poor?
Fault diagnosis: It is understood that the car belongs to the company and there is no special person to use it. Everyone complained that the car was uncomfortable to drive, no one wanted to drive, and no one asked about the maintenance of the car, so no one was interested in the company. After replacing the normal maintenance items such as oil three filters and spark plugs, the engine idling jitter phenomenon has not been significantly improved. Connect the fault detector to detect and read the fault code of the mixed gas concentration of the engine control unit; The fault code was not read in the ABS control unit. Then read the data flow of the engine system at idle speed. The absolute pressure of the intake manifold is 85 kPa (normally it should be about 35 kPa), and the signal voltage of the throttle position sensor is unstable. If it is greater than 750 mV, it should be 6 10 mV). Reading ABS data stream, no abnormal parameters are found.
After the engine is turned off, press the brake pedal several times to remove the residual vacuum in the brake vacuum booster pump, and then press the brake pedal to start the engine. It is found that the brake pedal will sink obviously, indicating that the brake vacuum booster pump should have no problem.
Unplug the vacuum tube and check valve of the brake vacuum booster pump, and check the check valve. There is no problem with the check valve; After starting the engine, the vacuum tube was blocked by hand, and it was found that the idle speed of the engine was still shaking, and there was no obvious improvement, thus confirming that the brake vacuum booster pump itself did not leak, but at the same time, it was found that the vacuum suction of the vacuum tube was obviously insufficient, and it was suspected that the brake effect was deteriorated due to the insufficient brake vacuum force. Because of the engine idling jitter, it was initially suspected that the engine power was insufficient due to the serious carbon deposition at the engine intake, so the intake manifold was removed, the carbon deposition above the intake and intake valves was cleaned, the throttle valve was re-matched with the fault detector, and then the engine was started for trial operation, but the engine working condition still did not improve significantly.
Considering that there is no abnormality in the ABS data stream read during the test run, and the absolute pressure of the intake manifold in the data stream is much higher than the normal value when the engine is idling, it is suspected that the timing belt is wrong, resulting in engine jitter and insufficient power. When the timing belt was removed to check the timing, it was found that the teeth of the timing belt were indeed staggered. Moreover, due to the excessive gap between the timing tensioner, idler and coolant pump, the timing belt moved outward and rubbed the timing cover and pulley, and the width of the timing belt was only half of that of the normal timing belt. Replace the timing belt, timing tensioner, idler gear set and coolant pump, and start the engine for test run after re-calibrating the timing. The engine idle speed is no longer dithered, the power is sufficient and the braking effect returns to normal. At this point, the fault has been completely eliminated.
Fault analysis: The 2.0 L EW 10A engine assembled on the triumph of Dongfeng Citroen is widely used by Dongfeng Citroen and Dongfeng Peugeot. The assembled models are Dongfeng Citroen Triumph, Sega, New C5, Dongfeng Peugeot 307 and 408. The timing belt assembly of this engine has strict requirements on the quality and technology of accessories. In addition, regarding the process, the clearance requirements between the coolant pump and the timing tensioner and idler are also very high. The accessory pulley outside the crankshaft timing gear cannot be obviously worn by the timing belt. After assembling the timing belt, the tensioning process must be carried out twice (the accessory pulley must be installed before starting the engine). The first tensioning is to tighten the tensioner to the tightest state. After starting the engine for a few minutes, let the timing belt be tensioned, and then adjust the tension to the normal tension. After the engine is idling for a few minutes, the timing belt cannot move outward to the same plane as the exhaust camshaft pulley, let alone exceed it.