I used an oscilloscope to look at the before and after replacing a fuel metering valve on the high pressure fuel pump.
the engine ran ok, except at idle when it would rev up and down with an uneven engine speed.
I could see a wave in the fuel rail signal voltage ( middle wire on the sensor at the end of the fuel rail)
also it looked like that was being controlled by the power train control module, because the duty cycle of the fuel metering valve was changing when the engine speed changed.
I fit a new valve and the engine ran and idle fine.
thanks for watching

свернуть