BMW 740Li CID display engine power down

A mileage of about 35,000 km of the 2009 BMW 740Li sedan. Reflects the owner : The car engine fault lights, while CID display engine power drop. When the fault is in the running speed 120 ~ 140km / h to appear, restart the stalled normal.
Troubleshooting : When you pick inspection found no fault lights on , should be in accordance with the requirements of the failure to reproduce the high-speed test, but Car LED Lamps considering driving safety ISID decided to carry out the diagnosis .
Fault diagnosis of turbo pressure is too low , failure, failure frequency twice does not currently exist , the details are all recent . Start the engine to check the vacuum source pressure 70kPa, circulating air valve for the vacuum control valve 45 kPa, vacuum suction table to detect normal valve to perform an action . Check the vacuum after vacuum accumulator is 70kPa, the degree of vacuum exhaust valve solenoid control post for 45 kPa, vacuum suction table to perform an action detection wastegate normal . External vacuum booster check valve operating rod normal shape without loose. Engine control module function reads data flow , throttle before the pressure is 100. 5 kPa, the pressure after the throttle after 460kPa normal throttle pressure should be around 38kPa. Check the rear throttle intake system piping and found no leaks case .
Troubleshooting: After replacing the Auto Diagnostic Tools catalytic converter test normal troubleshooting .
Fault Summary: TWC blockage caused by poor exhaust , causing pressurization system failure. Poor exhaust intake further reduced ability to cause the piston , resulting in increased intake manifold pressure , throttle the data is not normal . Failure is not a single solitary existence , failure phenomena reflect circumstances also reflected in other ways , so when troubleshooting a comprehensive analysis of the cause can not be considered a single thought to be a system failure , problems are often interrelated.

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