engines according to the invention is shown schematically in fig1 a throttle valve 14 is provided in an intake manifold 12 of for example a four cylinder engine 10 the throttle valve 14 has a throttle position sensor 16 associated therewith for outputting an electric signal representing the amount of opening of the throttle u03b8th to an electronic control unit hereinafter referred to as ecu 18 for each cylinder a fuel injection valve 20 is provided in the intake manifold 12 between the engine 10 and the throttle valve 14 at a point immediately upstream of an intake valve not shown each fuel injection valve 20 is supplied with fuel from a fuel tank 22 via a fuel pump etc not shown and is also electrically connected with the ecu 18 which supplies it with a drive signal for controlling its open time injection time tout spark plugs 24 associated with the respective cylinders of the engine 10 are electrically connected through an ignition distributor 26 with the ecu 18 which controls their ignition timing u03b8ig the lines connecting the spark plugs 24 and the ignition distributor 26 have ignition voltage sensors 28 capacitively coupled therewith so as to form multi pf capacitors with the lines the detection signals produced by the ignition voltage sensors 28.