Abstract: For a purpose of improving detecting performance toward knocking in small and middle intensity which must be detected as a top priority to conduct regulation of ignition timing, a device is provided to vary an output gain of an alternating component included in an ion current in accordance with ion current quantity. An ion current detector to detect the ion current to be generated surrounding an ignition plug just after mixed gas inside a cylinder has been ignited with a spark discharge having occurred at the ignition plug due to a voltage generated by an ignition coil, comprises a bias voltage generating part to generate a high voltage for an ion current detection to be applied to the ignition plug via the ignition coil, an ion current-to-voltage conversion part to convert an ion current having flowed between electrodes of the ignition plug by the high voltage into a voltage, and a knock signal generator to extract and amplify a frequency band resembling knocks on the basis of voltage conversion effect.

Abstract: A device for detecting knocking of an internal combustion engine which, even when spike noise is generated, does not erroneously detect it as knocking. An ionic current signal detected by an ionic current detecting unit 17 is separated into a knocking frequency component passing through a band-pass filter 32 and frequency components other than the knocking frequency component passing through a low-pass filter 321 and a high-pass filter 322. When the knocking frequency component is higher than a predetermined level, it is determined that the knocking is occurring. When the frequency component other than the knocking frequency component is higher than the predetermined level, it is regarded that the spike noise is generating, so that the generation of spike noise will not be erroneously determined as knocking.

Abstract: A glow sensor which combines functions of a diesel engine glow plug with an ion sensor for sensing engine combustion initiation and characteristics includes a ceramic rod retained in a supporting ceramic sleeve carried by a metal shell mountable in an engine cylinder head. The ceramic rod includes a heating element in a glow tip at the inner end of the rod which, in use, extends into an engine combustion chamber or pre-chamber. A conductive material such as platinum or palladium is coated on the lower end of the glow tip and connected by a conductor with a source of electric voltage. In use, the voltage produces a current carried by electrons generated by ionization of the combustion chamber gases during combustion. The current varies with the degree of ionization and the amount of electrons generated during various phases of the combustion event. The resulting information is usable in controlling engine operation or evaluating its operation for test purposes.

Abstract: A fuel cell anode for the oxidation of methanol, which contains at least one platinum metal or alloys of platinum metals as the primary, catalytically active component. The anode is characterized in that it also contains transition metal complexes of phthalocyanine or substituted phthalocyanines as cocatalyst, these amplifying the catalytic effect of the platinum metals and their alloys for the anodic oxidation of methanol.

Abstract: The invention is directed to a method of detecting combustion misfires of an internal combustion engine wherein an ion current is generated during the operation of the engine. The ion current signal is detected over a pregiven time interval starting with the discharge of a spark plug. The ion current signal is integrated over time with a weighting function to obtain a weighted integrated signal and the weighting function is adapted to previously detected ion current signals. The maximum of the weighted integrated signal is compared to a threshold value (s.sub.-- io) dependent upon engine rpm (nmot) and load (rl). A fault signal is outputted when the threshold value (s.sub.-- io) is not exceeded. The invention is also directed to an arrangement for detecting the combustion misfires.

Abstract: A combustion state detecting apparatus for an internal-combustion engine does not incur deteriorated ignition characteristics because the ionic current detecting circuit thereof is not affected by ignition current. The combustion state detecting apparatus is equipped with an ionic current detecting circuit (10A) which includes a biasing device (C) connected to the low voltage end of a secondary winding (2b) of an ignition coil (2) and which detects ionic current (i) flowing from the biasing device via a spark plug (4); rectifying device (5) which is inserted between the biasing device and the secondary winding so that the ionic current flows in the forward direction; a voltage clamping device (6) inserted between the secondary winding and the ground; and an ECU (20) which detects the combustion state according to the ionic current.

Abstract: A combustion monitoring apparatus for an internal combustion engine is provided which includes a voltage supply circuit, a combustion monitoring circuit, and a control circuit. The voltage supply circuit applies the voltage to plug electrodes of a spark plug mounted in a combustion chamber of the engine. The combustion ion monitoring circuit monitors a variation in amount of combustion ions existing between the plug electrodes to determine a combustion condition of the engine based on the current flowing through the plug electrodes produced by application of the voltage to the electrodes. The control circuit controls an operation of the voltage supply circuit so that the voltage is applied across the plug electrodes prior to a discharge duration of a spark plug mounted in the combustion chamber of the engine for monitoring preignition.

Abstract: A method and apparatus for detecting and displaying automotive fuel injector voltage signal pulse width which includes signal detection circuits for capturing the rising and falling edges of an input signal having positive and negative voltage swings is disclosed. Upon detecting a rising edge or a falling edge of a positive or negative voltage of the input signal, a corresponding software routine is executed to carry out the process of measuring the pulse width of a pulse of the input signal. The measured pulse width is then displayed in numerical and/or histogramic formats.

Abstract: An combustion state detecting apparatus for an internal-combustion engine is provided for preventing control errors and detection errors by preventing a biasing circuit from discharging at the start of energization, thereby allowing good sensitivity for detecting ionic current to be maintained. The combustion state detecting apparatus comprises an ionic current detecting circuit which includes a biasing circuit connected to the low voltage end of a secondary winding of an ignition coil and which detects ionic current flowing from the biasing circuit via a spark plug after the combustion of a fuel-air mixture. A current limiting circuit is provided between the low voltage end of the secondary winding and the biasing circuit. An electronic control unit detects the combustion state at the spark plug according to the ionic current.

Abstract: A discriminator circuit for detecting an event spark plug in a distributorless ignition system. The voltage waveform during event and waste cycles of the ignition system is conditioned and applied to a pair of comparators which compare the voltage waveform with different voltage reference levels. Both comparators switch states to a logical high level upon the firing of the event spark plug. The first comparator switches back to a low logical state after the end of the burn time in the event cycle. The second comparator remains in a high logic state following the burn time in the event cycle due to the negative voltage remaining on the spark cable, but switches back to a low logical state after the firing of the event spark plug in the waste cycle when the voltage on the spark plug cable goes positive. A delay element connected to the output of the first comparator holds the output of the first comparator at the high logical for a predetermined time period that is longer than the burn time in the event cycle.

Abstract: An oil deterioration and contamination sensor includes a housing, a substrate with a first capacitive plate mounted within the housing, a second capacitive plate mounted to the housing close to the first capacitive plate, and a total reference capacitor which includes an external fixed reference capacitor. The second capacitive plate is mounted to the housing such that at least one fluid including oil freely circulates within a gap between the first and second capacitive plates thereby defining an oil deterioration and contamination sensor capacitor. The respective capacitances of the oil deterioration and contamination capacitor and the total reference capacitor provide an indication of a dielectric constant of the at least one fluid including oil within the gap.

Abstract: The quality of a fuel-air mixture shall be evaluated by a process and a device during a phase of combustion, especially in a spark ignition engine, in order to make possible a low-emission, fuel-saving and knock-free operation. An electrical testing pulse P is sent for this purpose to the spark plug during the phase of combustion V following the ignition pulse Z. The effect of the actual fuel-air mixture of the combustion chamber on the testing pulse is detected and evaluated as an electrical variable.

Abstract: A method and apparatus for detecting and displaying automotive fuel injector voltage signal pulse width which includes signal detection circuits for capturing the rising and falling edges of an input signal having positive and negative voltage swings is disclosed. Upon detecting a rising edge or a falling edge of a positive or negative voltage of the input signal, a corresponding software routine is executed to carry out the process of measuring the pulse width of a pulse of the input signal. The measured pulse width is then displayed in numerical and/or histogramic formats.

Abstract: An alternating current ignition system which can be used in one of two ways for ion current measurement. On the one hand, an oscillating circuit at the primary end of the ignition coil can be driven such that, after ignition has taken place, an alternating current signal is generated at the primary end; the amplitude of the alternating current signal must be sufficiently low so as not to cause any sparks at the secondary end, but lead to an alternating voltage signal which is modulated in relation to the ionisation degree of the ignition spark gap and thus represents an ion current measurement signal. On the other hand, however, if an auto transformer is used as an ignition coil, the intermediate circuit voltage applying at the primary end will be modulated in the medium-high voltage range of, e.g, 180 V in relation to the degree of ionisation, so that this supply voltage is used as a measurement signal.

Abstract: Provided is a high power ignition system for internal combustion engines with a detection circuit for sensing and measuring ionization in a spark plug gap. The detection circuit utilizes a dual-purpose second energy source to apply the voltage necessary to generate a high current arc and then an ionization current. A signal processor analyzes an ionization signal created by the detection circuit to derive useful ignition system data such as engine misfire, combustion duration, engine knocking, approximate air/fuel ratio, indications of spark plug fouling, and preignition.

Abstract: To correctly sense combusting conditions of an internal combustion engine, an ion current caused by combustion is detected.

Abstract: A piston-type internal combustion engine includes an engine cylinder; a piston slidably received in the engine cylinder; and a device, carried by the piston, for measuring deformations in the cylinder wall. The piston has at least two radial bores. The measuring device includes a separate carrier element disposed in each radial bore. The carrier elements are attached to the piston in a region of the piston axis such as to be displaceable relative to the radial bores, whereby a relative motion between the piston and each carrier element is provided upon radial expansion and contraction of the piston. The measuring device further includes a separate, electrically inductive path sensor, which is electrically connectable to a measuring and evaluating device, and which is attached to a respective carrier element such that the path sensor remains out of contact with the cylinder wall at all times during movement of the piston relative to the engine cylinder.

Abstract: Secondary current circuits are monitored in an ignition device of an externally ignited internal combustion engine having at least two primary current circuits each being closed and opened by one ignition end stage transistor. A base-to-emitter voltage of each ignition end stage transistor is measured and stored in memory with the primary current circuit closed. A comparison value is formed from at least two successive measured values and compared with a limit value. A failure signal is output as a function of the comparison. An apparatus for monitoring the secondary current circuits includes an engine or ignition control unit for making the ignition end stage transistors conducting or nonconducting.

Abstract: A microprocessor based electronic control module with an EEPROM for storing protected data allows the data to be used internally, and allows non-sensitive data to be accessed by external communication tools, but prohibits access to the protected data unless a password is first entered. Then the data may be read from memory and the data or the password may then be changed. For a given model of control module, an ID number is assigned to the password and stored in the module, and can be read to allow the user to find the corresponding password on a secure list available only to authorized personnel. When a password can not be found and it is necessary to change the protected data, the unit can be recovered by a recover procedure wherein the secure data is first erased and then the security is deactivated to grant free access.

Abstract: An antenna for a magnetic resonance apparatus has an antenna conductor that can be adapted to examination regions of different sizes, with one region of the antenna conductor divided into conductor sections. The conductor sections are connected to one another via capacitive elements, with the conductor sections and the capacitive elements connected alternating in series. The conductor sections are connectable to the remaining antenna conductor via releasable electrical connections.

Abstract: An apparatus for detecting a misfire in an internal combustion engine that is capable of preventing erroneous detection in a period in which the discharged voltage on a secondary ignition coil is charged. The apparatus having a capacitor, which is supplied with bias voltage from a primary side of an ignition coil to be electrically charged to apply the charged voltage to the spark plug at the time of discharge of the spark plug to cause an ionic current to flow and a misfire detection circuit for determining whether or not a misfire has taken place in accordance with detection of the ionic current flowing from the capacitor.

Abstract: A misfire-detecting system for an internal combustion engine detects occurrence of a misfire in the engine, based on voltage between both ends of a spark plug assumed when sparking discharge takes place at the spark plug. A diode is arranged in an ignition secondary circuit of the engine, for checking reverse current flowing in the circuit in a direction reverse to the direction of flow of current occurring when spark ignition takes place at the spark plug. An ECU detects reverse current flowing in the ignition secondary circuit, and detects an abnormality of the diode, based on the detected reverse current.

Abstract: An ignition system for internal combustion engines serves as a bracket circuit arrangement (10, 11, 12, 16) to limit the primary voltage, in order to protect parts energized with high voltage from being destroyed. The ignition system comprises a voltage bracketing of the ignition transistor (3), the bracketing voltage being variable in dependence upon a secondary-side load. The primary voltage (U.sub.P) is acquired by an evaluation unit (9) and, given a high secondary load, a high bracketing voltage is used and, given a low secondary load, a low bracketing voltage is used.

Abstract: A combustion detect device for use in an internal combustion engine including an ignition coil in which a high voltage for ignition is generated at a secondary winding when the current of a primary winding is cut off, and an ignition plug for discharging and igniting a mixture gas when said high voltage for ignition is applied thereto, the combustion detect device comprises an ion current detection device for detecting an ion current generated due to combustion of a mixture gas by applying a voltage to an ignition plug and a restriction device for restricting a voltage generated in the secondary winding when a primary winding is turned on to conduct.

Abstract: The invention is a method and apparatus for extracting and analyzing features in real time from primary or secondary ignition waveforms, including engine probes, sampling device, and a processor that extracts from the waveform features such as peak firing height, firing line duration, firing line slope, firing line noise, post firing line duration, primary oscillations, and dwell interval duration and compares them against fixed thresholds and running averages to detect anomalies. Anomalies are reported as they occur allowing diagnosis of transient events as well as steady conditions. Waveforms with or without anomalies may be stored and retrieved as needed.

Abstract: In a misfire detector device for use in internal combustion engine, an electrical interrupter circuit on-off actuates a primary current flowing through a primary circuit of an ignition coil to induce a spark plug voltage. A check diode is provided in a secondary circuit of the ignition coil to prevent a current flowing back to the ignition coil. The spark plug has a center electrode, a front end of which is projected from an insulator, and an outer surface area of the projected front end being 25 mm.sup.2 or more. A spark plug voltage detector circuit detects an attenuation time length of a spark plug voltage waveform presented subsequent to a predetermined time period occurring after an end of a spark action of the spark plug. On the basis of the attenuation time length, a distinction circuit determines whether a misfire occurs in a cylinder of an internal combustion engine.

Abstract: In a misfire detector device for use in internal combustion engine, an electrical interrupter circuit on-off actuates a primary current flowing through a primary circuit of an ignition coil to induce a sparkplug voltage which is applied to a multi-electrode type spark plug. A check diode or a series gap is provided in a secondary circuit of the ignition coil so as to prevent a current flowing back to the ignition coil. A sparkplug voltage detector circuit detects an attenuation time length of a sparkplug voltage waveform presented subsequent to a predetermined time period after an end of a spark action of the spark plug. On the basis of the attenuation time length, a distinction circuit determines whether a misfire occurs in a cylinder of an internal combustion engine.

Abstract: A misfire-detecting system for an internal combustion engine detects a value of the sparking voltage generated by the igniting device after generation of the ignition command signal, determines the duration of a discharge of a spark plug, based upon the detected sparking voltage, and determines whether or not a misfire has occurred in the engine, based upon the determined duration of the discharge. For example, the misfire-detecting system measures the duration of the discharge from the time of generation of the ignition command signal, based upon the detected sparking voltage, compares the measured duration of the discharge with a predetermined time period. When the measured duration is shorter than the predetermined time period, it is determined that a misfire has occurred in the engine.

Abstract: A monitoring apparatus, which reads a number of internal combustion engine temperatures and engine revolutions per minute, displays either a current or a peak reading of one of these parameters using a digital readout. Transducers convert the various physical parameters to analog voltages. A digital potentiometer, comparator and logic circuitry are used to step the potentiometer output to a greater value only to equal the highest input voltage. This stores the peak voltage for that parameter in analog form. Each parameter has this equipment, which results in all of the parameters having the peak value tracked simultaneously. A multiplexer selects one of the parameters, either peak or current. This selected parameter is then converted by an analog to digital converter to a set of four binary coded decimal numbers. These numbers are then displayed on a liquid crystal display.

Abstract: A misfire-detecting system detects a misfire occurring in an internal combustion engine in such a manner that a value of discharge current is detected when sparking voltage is generated in response to an ignition command signal, the detected value of discharge current is compared with a predetermined current value, and it is determined that a misfire has occurred when a time period over which the detected discharge current value after generation of the ignition command signal is above the predetermined current value is shorter than a predetermined time period.

Abstract: A controller for a device moving along a complementary path to a conveyed object, derives basic speed input from the object conveyor and uses a non-invasive sensor system to detect the proximity of the object. The sensor system controls electronic logic which causes a drive unit to match the speed of the device to that of the object over the complementary path. The controller returns the device to the start of the path for iterative utilization.

Abstract: A linearly moving external part on a multi-cylinder internal combustion engine is contacted with a hand-held rotary encoder, contact tachometer having a hollow handle in which processing circuitry is disposed for converting the rotary encoder output to a waveform signal. This signal, along with a signal responsive to the firing of the number one cylinder, are applied to an engine analyzer processor for display of a single engine cycle of the waveform signal on the CRT oscilloscope of the engine analyzer. The variations in amplitude of the waveform signal correspond to speed variations of the moving part over an engine cycle to give an indication of the relative power contributions of the individual cylinders.

Abstract: An ion current sensing device for an internal combustion engine is able to accurately sense an ion current generated between electrodes of a spark plug during combustion of a mixture even when the electrodes have been smeared by carbon or other combustion products deposited or accumulated thereon. A power source 14 supplies a bias voltage to the electrodes of the spark plug. An ion current sensing resistor 15 is connected between the elecrodes of the spark plug and the power source for sensing an ion current as generated between the electrodes of the spark plug each time a mixture in the combustion chamber is combusted. A comparator 11 compares the voltage across the ion current sensing resistor with a reference voltage and generates an output signal when the voltage is higher than the reference voltage.

Abstract: An automated test system makes voltage and resistance measurements. The breakout cable is connected between the vehicle electronic control module and the vehicle sensors and controls. Resistance measurements are made between a selected pair of connector pins of the breakout cable by connecting a current loop (which includes a power supply and a known resistance) through a first multiplexing circuit to the selected pair of pins. A voltage measuring circuit measures voltage across the known resistance and between the pair of pins. The voltage measuring circuit includes a second multiplexing circuit and a voltmeter. The second multiplexing circuit receives inputs from the various pins, as well as from opposite sides of the known resistance in the current loop. The second multiplexing circuit provides its output to the voltmeter for measurement. By measuring the voltage across the known resistance, and the voltage between the selected pair of pins, the resistance between the two pins can be derived.

Abstract: For processing data relating to the performance of an apparatus, the data is analyzed using a Kalman Filter. After a first pass of data through the filter, the results are refined by discarding at least one less significant component performance change and/or sensor bias. The Kalman Filter is then re-run using the modified data. As further runs of the Kalman Filter are performed, as required, the input of each successive run is refined by discarding from the preceding run at least one further component performance change and/or sensor bias. For each run, an objective function is evaluated for the amount of unexplained measurement change and/or the amount of component performance change and sensor bias. The run whose results show an acceptable value for the objective function is selected as the best solution. In this way, the tendency of the Kalman Filter to distribute the cause of any sensed performance change over all the possible sources of that change is avoided.

Abstract: The apparatus for measuring the comparative output power of each cylinder of a multi-cylinder engine comprises a digital signal processor 1 and a phase locked loop detector 2. By inputting instantaneous current measurements from (e.g.) a current transformer attached to an alternator output of an engine under test and analysing same in the processor 1, instantaneous engine speed may be measured. This measurement may be processed to determine comparative measurements of compression and power output of each of the cylinders.

Abstract: The method and apparatus allows the detection and indication of anomalies in the operation of the ignition system of an internal combustion engine including a plurality of spark plugs, each of which receives a periodic high-voltage pulse output by a high-voltage generator in operation. The method includes the steps of:detecting the pulses generated by the high-voltage generator,comparing the peak values of each pulse detected with first and second threshold values, andproducing a perceptible signal when the peak values of the high-voltage pulses fall outside the acceptable range defined between the threshold values.

Abstract: The system enables the diagnosis of anomalies or breakdowns in a plurality of types of electronic control systems (S), each of which includes, in known manner, a plurality of sensors (2) and electrically-controlled actuators (3) connected to an electronic control and operating unit (1), which is different for each type of control system (S). This unit (1) is programmed to carry out auto-diagnosis of anomalies or breakdowns in the control system (S) and to provide serial-type electrical auto-diagnosis signals at an output (5), the signals containing information on the operating conditions of the control system (S). The various control systems (S) each have the same standard electrical connector (6) connected to the output (5) of the respective control unit (1). Each time it is actuated, the electronic control unit (1) of each system (S) outputs at the output (5) a serial-coded identification message of the type of control system (S) to which the unit (1) belongs.

Abstract: The signal provided by an accelerometric sensor (S) connected to the engine is monitored in two frequency bands (f1, f2) in which peaks indicative of the presence of pinking (knocking) may appear. The intensity of the signal detected in the second band (f2) is compared (3) with the intensity of the signal detected in the first band (f1). The comparison (20) of the detection-signal component (F1 and/or F2) with the noise component (F3), in view of the emission of the pinking signal (21), is carried out in different ways (8, 13, 14) according to the relative ratios between the above intensities.

Abstract: An electric motor is tested by sensing the phase of an alternating current waveform to be applied to the motor, and applying the waveform to the motor in response to the phase of the waveform reaching a preselected value to start the motor. The voltage and current are sampled at predetermined times measured from the application of the waveform to the motor until a predetermined number of voltage and current samples are obtained. Parameter samples are generated from the voltage and current samples, the parameter being a function of the applied voltage and current. The parameter samples are compared with a previously obtained set of reference parameter sample values, the reference sample values having error limits for each reference sample value. The motor is rejected if at least a predetermined number of the parameter samples fall outside the error limits for those particular samples.

Abstract: An ignition monitoring circuit for an ignition system of an internal combustion engine of an automobile, which comprises, in addition to a pulse height and a pulse width shaper circuit, a circuit for eliminating an initial erroneous pulse which is generated from the pulse width shaper circuit upon making of the key switch. The pulse height shaper circuit shapes impulses corresponding to an ignition voltage into pulses of predetermined height; the pulse width shaper circuit shapes the output pulses of the pulse height shaper circuit into pulses of predetermined width. The eliminating circuit comprises: a serial circuit of a resistor, a diode, and a capacitor, coupled across the battery; and a transistor, having its base coupled to the output terminal of the pulse height shaper circuit through an inverter, which is coupled in parallel with the serial connection of the diode and the capacitor.

Abstract: A microprocessor controlled digital engine analyzer receives analog input signals from an engine being analyzed, engine parameter data entered via a keyboard, and function data, selecting one of several operating modes for the analyzer and which information is to be displayed, entered via the keyboard, and displays on a CRT screen the selected information such as cylinder firing order,RPM, Dwell, KV and DC volts, alphanumerically, information such as primary and secondary ignition and voltage, alternator and fuel injector information through the use of continuous waveform patterns, and additional information pertaining to Dwell, KV and Cylinder Shorting through the use of bar graphs.

Abstract: An advance reference cylinder trigger generator that provides a more effective trigger signal to synchronize the horizontal sweep of a cathode ray tube based instrument used for troubleshooting, diagnosing and servicing of spark ignition internal combustion engines. The trigger pulses, V.sub.pt, derived from the primary winding of an ignition coil are applied to a cylinder position counter (5) and, after being delayed by a delay circuit (4), to a cylinder count counter (8). When the value of cylinder position counter (5) equals or exceeds the value of cylinder count counter (8), an output from comparator (6) enables a monostable multivibrator (10) to produce an advance reference cylinder trigger V.sub.at upon receipt of the next ignition coil derived trigger pulse, V.sub.pt. Because the V.sub.pt pulses lead spark plug discharge derived pulses, the V.sub.pt pulses lead the spark plug discharge pulse associated with the V.sub.pt pulse causing the firing of the monostable multivibrator.

Abstract: A universal sensor includes a dielectric substrate, a curved surface capacitive plate mounted to the substrate and responsive to the electromagnetic field (EMF) of an integral coil ignition system, and a rotatable lever arm mounted to the substrate and having wire holders for receiving the EMF of spark plug wires of a distributorless ignition system (DIS)ignition, the arm operable in a closed position to conduct the DIS EMF to the plate, and operable in an open position for securing a standard ignition coil secondary wire between the arm and the plate allowing the standard wire EMF to be coupled to the capacitive plate.

Abstract: The Ignition Performance Measuring Circut is intended for use with dual ignition systems, such as the dual-magneto ignition systems used on light aircraft. The circuit has a first and second channel. The first channel is dedicated to measuring the relative peak amplitude of amplitude difference signals, i.e. the algebraic difference between concurrent left and right conditioned ignition signals. Signal conditioning is performed by an input attenuator and a difference amplifier. The circuit operates without benefit of a positive synchronization. To any particular cylinder's ignition firing signals. The pilot of an aircraft using the invention circuit will be alerted to the presence of a degraded firing signal but will not be advised as to which cylinder or spark plug is contributing to the failure indication. The circuit has a peak detection network for selecting the largest amplitude difference signal from each series of firing signals.

Abstract: An equipment for recognizing misfiring, which is particularly suitable for permanent installation in a motor vehicle. By means of high-pass filters coupled to the plug leads between the spark distributor and the spark plugs, the change to the voltage at the spark plugs associated with the initiation of the ignition spark is sensed. The high-pass filters are so arranged that they only send on a needle-shaped output pulse signal to an analysis circuit if it appears with the change in voltage associated with the spark front. The analysis circuit generates appropriate output signals with reference pulses generated in time with the ignition pulses. The high-pass filters are preferably arranged as simple RC filters whose capacities are coupled to the plug leads by means of peripheral electrodes, which at least partially surround the insulation coatings of the plug leads.

Abstract: A portable case structure functions as the depository, transporter and remote, work site satellite for a plurality of engine sensor probes which communicate with a parent test console through a common electrical umbilical connection.

Abstract: This specification discloses testing vehicle primary ignition systems by taking the integral of the primary spark plug firing voltage versus time over a time period when the spark should occur. To determine when an integration output should be evaluated, a phase locked loop circuit is used to predict the occurrence of an ignition firing pulse. To compensate for changes in engine speed and yet disregard extraneous spark plug firings, the phase locked loop circuit contains two loop filters having different response times which are automatically selected to minimize response to erroneous or missing spark plug firings and maximize response to actual engine RPM changes.

Abstract: Cylinder engine data, is displayed in a bar chart graphics mode format on a cathode ray tube (CRT); the data from each cylinder is displayed in dual bar segments comprising a first bar representing the mean value and a second bar representing the mean deviation of the measured parameter data, the first bar extending from a zero baseline on the abscissa to the mean measured value as represented graphically by comparison to a scaled ordinate, the second bar being generally centered about the first bar mean value and extending at its end points to the actual peak and actual minimum values of the selected parameter.

Abstract: A diagnostic apparatus for an internal combustion engine ignition system measures the rise of the secondary voltage at the ignition coil represented by time lapse between initiation of the secondary voltage rising and occurrence of break and the ignition coil primary breaking current value. Results of the measurement are computed to determine stray capacitance existing in the internal combustion engine ignition system and secondary voltage.