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故障现象一辆上海大众帕萨特B5 1.8T轿车,已经行驶了16万多km,因发动机动力下降且烧机油严重而进厂进行了发动机大修,但完成发动机大修后试车发现,发动机没有怠速,只要一松开加速踏板,发动机就熄火,且怠速喘振严重,只有将发动机转速稳定在1 300 r/min左右时发动机才不熄火,但原地加速正常。故障诊断根据故障现象,初步判断是发动机进气系统有严重漏气的地方。经仔细排查,发现位于进气歧管下方的涡轮增压器空气再循环控制阀(N249)进气真空管未连接,而且与废气阀连接的真空管与通向燃油蒸发控制阀的真空管装错,将错装的部位恢复正确安装后继续试车,发现
Fault phenomenon A Shanghai Volkswagen Passat B5 1.8T sedan, has been traveling more than 160,000 km, due to engine power down and burning oil into the plant was overhauled engine overhaul, but after the completion of the engine overhaul test found that the engine did not idle, as long as a When the accelerator pedal is released, the engine will stall and the idling surge will be serious. Only when the engine speed is stabilized at about 1 300 r / min will the engine not stall, but the speed will be normal. Fault diagnosis According to the fault phenomenon, the initial judgment is that the engine intake system has a serious leak. After careful investigation, it was found that the intake manifold of the turbocharger air recirculation control valve (N249) located below the intake manifold was not connected, and the vacuum tube connected to the exhaust valve and the vacuum tube leading to the fuel evaporation control valve were installed incorrectly The wrong parts to restore the correct installation after the test and found