Ignition secondary analyzer

Apparatus for analyzing the secondary ignition circuit of a spark ignited internal combustion engine to identify the location of faulty portions of the circuit, said circuit having induction coil means for generating sparking voltage pulses repetitively, and distributor means for cyclically distributing said voltage pulses to respective spark plugs in a predetermined order, said apparatus comprising:

• measuring means coupled to said secondary ignition circuit for producing measurement signals identifying the peak amplitude of respective voltage pulses of one polarity developed at a single point in said secondary ignition circuit for respective said spark plugs in each engine cycle,
• integrating means coupled to said secondary ignition circuit for producing a comparison signal identifying the average peak amplitude of voltage pulses of said one polarity developed for all said spark plugs,
• offset means for producing an offset signal,
• comparator means for comparing successive measurement signals with said comparison signal and producing a fault signal when a said measurement signal differs from said comparison signal by more than said offset signal, and
• indicating means responsive to a said fault signal for indicating a fault.

A method for analyzing the secondary ignition circuit of an internal combustion engine to identify the location of faulty portions of the circuit, said circuit having means for generating a succession of high voltage outputs from a coil, and means for distributing said outputs to a plurality of portions of said circuit in a predetermined order, each said portion including a spark plug, said method comprising:

• measuring the voltage of each output of said coil;
• storing a first reference voltage which is indicating the average of the positive components of said measured output voltages;
• storing a second reference voltage which is indicating the average of the negative components of said measured output voltages;
• comparing each successive measurement of the output of said coil with said reference voltages and generating data to identify faults in said circuit if the positive component of said output exceeds said first reference voltage by a predetermined differential, if the negative component of said output exceeds said second reference voltage by a predetermined differential, or if the negative component of said output is less than a predetermined amplitude;
• identifying the portion of said circuit to which each said output is distributed;
• and
• displaying said data to identify the location of any faulty portions detected by said comparing means.

A method for analyzing the secondary ignition circuit of a spark ignited internal combustion engine to identify the location of faulty portions of the circuit, said circuit having induction coil means for generating sparking voltage pulses repetitively, and distributor means for cyclically distributing said voltage pulses to respective spark plugs in a predetermined order, said method comprising:

• measuring the amplitude of respective voltage pulses of one polarity developed at a single point in said secondary ignition circuit for respective spark plugs in each engine cycle and producing measurement signals indicating said amplitudes,
• deriving a comparison signal indicating the average measurement signals developed for all spark plugs,
• comparing successive measurement signals with said comparison signal, and
• indicating a fault when a said measurement signal differs from said comparison signal by more than a predetermined differential.

A method for analyzing the secondary ignition circuit of a spark ignited internal combustion engine to identify the location of faulty portions of the circuit, said circuit having induction coil means for generating sparking voltage pulses repetitively, and distributor means for cyclically distributing said voltage pulses to respective spark plugs in a predetermined order, said method comprising:

• measuring the peak amplitude of respective voltage pulses of one polarity developed at a single point in said secondary ignition circuit for respective said spark plugs in each engine cycle and producing measurement signals indicating said amplitudes,
• deriving a comparison signal indicating the average peak amplitude of voltage pulses of said one polarity developed for all said spark plugs,
• comparing successive measurement signals with said comparison signal, and
• indicating a fault when a said measurement signal differs from said comparison signal by more than a predetermined differential.