Abstract: A method for determining the wear rate of a spark plug electrode of an ignition system of an internal combustion engine comprises determining a risetiine number indicating the time required for raising the current and thereby the primary energy which is supplied to an ignition coil of the spark plug from an inactive level to a predetermined level, determining an operating condition indicator configured to indicate an operating condition of the ignition system, determining a wear rate of the spark plug electrode based on a difference of a first spark plug state indicator at a first time instance and a second spark plug state indicator at a second time instance, wherein the first time instance and the second time instance are separated by a predetermined time interval, wherein the spark plug state indicator is determined as a value based on the risetime number and the operating condition indicator.

Abstract: A personal consumer product having an energy emitting element in selective electrical communication with a power source is provided. Thermal control circuitry is used to isolate the energy emitting element from the power source when a temperature of the energy emitting element exceeds a threshold. A diagnostics routine is used to test the functionality of the hardware and software of the personal consumer product.

Abstract: An air operated pump 10 uses a magnet 14 mounted in the valve cup 16 of the air motor 18 and two reed sensors 20 mounted in the valve cover 22 to monitor the speed and position of the valve 16. A solenoid 24 is mounted on the valve cover 22 and can be commanded to extend a plunger 26 into the valve cup 16 to stop valve movement and therefore the pump from running away A magnetoresistive sensor 34 is located in the center of the air motor 18 to precisely monitor the piston 36 position and with air valve sensors 20 provides the input necessary for precise control and diagnostics of the pump 10 and makes it suitable for metering and plural component application.

Abstract: A combustion state detection apparatus for an internal combustion engine, includes convexity detection means (30) for detecting that domain within the detection interval in which the change shape of the ionic current is upwardly convex, on the basis of the ionic current data extracted by data extraction means (20), and preignition decision means (40) including comparison setting means for setting a comparison value with which the upwardly convex domain is compared, and functioning to decide the occurrence of the preignition or the premonitory phenomenon thereof when the upwardly convex domain lies at a timing earlier than the comparison value, wherein the convexity detection means (30) includes leak current judgment means for judging the appearance of a leak current across electrodes, and it enables the detection of the upwardly convex domain when the appearance of the leak current has been judged.

Abstract: An aircraft monitoring system uses aircraft engine and system transducers to monitor critical engine and aircraft system parameters. Simple controls and graphical user interfaces facilitate the display of different kinds of critical information to the pilot. Such data may also be recorded for later downloading and analysis.

Abstract: A combustion state detection apparatus for an internal combustion engine, includes convexity detection means (30) for detecting that domain within the detection interval in which the change shape of the ionic current is upwardly convex, on the basis of the ionic current data extracted by data extraction means (20), and preignition decision means (40) including comparison setting means for setting a comparison value with which the upwardly convex domain is compared, and functioning to decide the occurrence of the preignition or the premonitory phenomenon thereof when the upwardly convex domain lies at a timing earlier than the comparison value, wherein the convexity detection means (30) includes leak current judgment means for judging the appearance of a leak current across electrodes, and it enables the detection of the upwardly convex domain when the appearance of the leak current has been judged.

Abstract: The ignition apparatus includes an electronic control unit and an igniter. The igniter detects ions resulting from ignition, and sends an ion current output signal to the electronic control unit. The igniter has a waveform shaping circuit and an ion current detecting/outputting circuit. The waveform shaping circuit is adapted such that a voltage at an input terminal thereof becomes higher than a predetermined reference voltage to turn the switching element ON when the ignition signal is caused to flow through an electric load. The ion current detecting/outputting circuit has an output terminal which is connected to the input terminal and outputs therefrom an ion current output signal obtained as a result of conversion of an ion current, and is adjusted such that the voltage at the input terminal at the time when the ion current output signal is outputted to the electronic control unit becomes lower than the reference voltage.

Abstract: A variable reluctance sensor for use with an ignition timing device includes a support tube insertable in a bore extending from a first end to a second end. A sensor housing is insertable in the bore, while a variable reluctance probe is disposed in the sensor housing.

Abstract: A variable reluctance sensor for use with an ignition timing device includes a support tube insertable in a bore extending from a first end to a second end. A sensor housing is insertable in the bore, while a variable reluctance probe is disposed in the sensor housing.

Abstract: A method for switching on an inductive load, in particular an ignition coil, whose current is intended repeatedly to reach a predefined variable end value at a respectively predefined variable time, includes measuring the time interval between the switching-on action and reaching at least one predefined intermediate value. This time interval and the at least one predefined intermediate value are used to calculate the anticipated time from switching on until the end value is reached. A following switching-on action is carried out at the calculated time before the respectively predefined time.

Abstract: A method for generating a control signal after a predeterminable period of time is described. The method includes applying a voltage to an inductor at a beginning of a time measurement; and outputting, via a current threshold value detector, the control signal if a current through the inductor exceeds a predeterminable threshold value. The invention also relates to a timing circuit.

Abstract: The present feature of the invention is generally directed to a subsystem of an ignition diagnostics and feedback control system using ionization current feedback. It utilizes the ionization signal from an ionization detection circuit to monitor ignition parameters, such as primary charge timing, primary charge duration, ignition/spark timing, and ignition/spark duration for future “smart” ignition system control. In addition, the ionization signal is also used to detect spark plug carbon fouling, as well as plug insulator overheating. These parameters can be monitored for every cylinder of the engine for each engine cycle.

Abstract: A rotation sensor that is particularly useful to provide a control with an indication of shaft position. The sensor utilizes a magnetic connection between a cam follower and a transducer. The magnetic connection eliminates problems in the prior art such as degradation due to wear and corrosion. In particular, a rotating shaft carries a cam. The cam drives a cam follower. As the cam follower moves, a magnet moves. The transducer can sense movement of this magnet. In preferred embodiments, the cam follower is driven to pivot and the magnet is mounted on the pivot point of the cam follower. The present invention is useful in many distinct control applications such as motorcycle throttle handles, accelerator pedals, brake pedals, and detecting shaft position for valve timing.

Abstract: An ignition timing device for timing an engine having a timing port and a timing mark indicative of a position of a movable member. The ignition timing device includes a sensor adapted to be secured in the timing port to provide a timing mark signal indicative of presence of the timing mark. Also, an ignition sensor is adapted to provide an ignition signal indicative of the occurrence of an ignition spark. A filter receives the ignition signal and provides a filtered ignition signal. The filter filters ignition sparks of compression strokes from ignition sparks of compression and exhaust strokes of a selected cylinder to provide the filtered ignition signal. Also, the delay element is provided that receives the filtered ignition signal and provides a delayed signal having a selected delay from the filtered ignition signal. A comparator receives the timing mark signal and the delayed signal.

Abstract: The present invention related generally to a method for determining spark plug malfunction and more particularly to a method for determining spark plug malfunction in an internal combustion engine in which at least two spark plugs are disposed in each cylinder. In a dual plug configuration, a spark plug malfunction is detected by disabling one of the spark plugs during a test period in a particular cylinder. A misfire provides an indication of malfunction of the other spark plug.

Abstract: A signal to be produced, which represents a digital data stream, is generated using the currents or voltages from current or voltage sources selected from multiple current or voltage sources. The current or voltage sources whose currents or voltages are used to generate the signal which is to be produced are selected based on the contents of the elements of a shift register whose input connection has the signal which is to be filtered applied to it.

Abstract: A method of detecting spark plug fouling in an internal combustion engine is provided. The method comprises calculating an integration value of discharge current flowing between electrodes of a spark plug during a period of a spark discharge and judging if the calculated discharge current integration value is smaller than an integration value criterion. The integration value criterion is set at such a value that can discriminate between normal discharge and interior jumping (i.e., jumping due to short circuit caused by fouling). When the calculated discharge current integration value is smaller than the integration value criterion, it is judged that the spark plug has been fouled. By this, it becomes possible to detect a spark plug fouling before the electrodes of the spark plug are short-circuited and disabled to generate spark discharge, i.e., before the spark plug is fouled to such an extent as to cause a misfire. An ignition system for detecting spark plug fouling is also provided.

Abstract: An ignition timing device for timing an engine having a timing port and a timing mark indicative of a position of a movable member. The ignition timing device includes a sensor adapted to be secured in the timing port to provide a timing mark signal indicative of presence of the timing mark. Also, an ignition sensor is adapted to provide an ignition signal indicative of the occurrence of an ignition spark. A filter receives the ignition signal and provides a filtered ignition signal. The filter filters ignition sparks of compression strokes from ignition sparks of compression and exhaust strokes of a selected cylinder to provide the filtered ignition signal. Also, the delay element is provided that receives the filtered ignition signal and provides a delayed signal having a selected delay from the filtered ignition signal. A comparator receives the timing mark signal and the delayed signal.

Abstract: An internal combustion engine is equipped with a plurality of cam sensors that output cylinder discrimination signals during every uneven crank angle interval, and specific cylinders are discriminated based on said cylinder discrimination signals output from said plurality of cam sensors. Based on the discrimination result of said specific cylinder and said cylinder discrimination signals from cam sensors, the cylinders other than said specific cylinders are discriminated.

Abstract: A cylinder identifying apparatus comprising a crank angle sensor 20 detecting a crank angle of a combustion engine 14 having a plurality of cylinders, a cylinder identifying means 31 identifying a cylinder to be controlled by an output signal from the crank angle sensor 20, a cranking judging means 34 detecting a cranking state of the combustion engine 14, and an erroneous cylinder identification preventing means 32 detecting starting of cranking of the combustion engine 14 by an output from the cranking judging means, and circumventing the cylinder identification by the cylinder identifying means 31 until a predetermined time passes after starting the cranking, whereby the cylinder to be controlled is securely identified at time of cranking, and erroneous detection, erroneous control, and detection delay are prevented.

Abstract: An ignition timing device for timing an engine having a timing port includes a sensor securable in the timing port to provide a timing mark signal. An ignition sensor is adapted to provide an ignition signal. A comparator receives the timing mark signal and the ignition signal. The comparator provides an output signal indicative of substantial simultaneous occurrence of timing mark signal and the ignition signal. An indicator receives the output signal and is operable as a function thereof.

Abstract: An engine ignition timing tool is provided for use with a strobe timing light in setting the timing of Harley-Davidson motorcycle engines The timing display tool includes a modified circuit breaker cam bolt having a pointer indicator attachable to a cam assembly of the engine, and an ignition timing measuring plate attachable to a gear cover of the engine. The timing display tool is installed on the side of the engine having the ignition unit where the ignition timing is to be set. The engine is run and the strobe timing light is set to the engine spark firing frequency then shone onto the pointer indicator and measuring plate so that the pointer indicator is illuminated at a timing mark corresponding to the degree of spark advance or retard of the engine. The ignition timing is then adjusted.

Abstract: A compression sense ignition system includes a sensing capacitor having a conductive sensing element disposed in proximity to the secondary winding leads of a first and a second ignition coil for developing a compression sense ignition signal. Epoxy potting material encapsulates the leads and the sensing element to reduce variation of the effective capacitance of the sensing capacitor. The compression sense ignition signal is processed to generate a cylinder identification signal which is used to determine absolute engine position. A fault mode detection and correction scheme is implemented wherein a controller responsive to the cylinder identification signal can determine correct absolute engine position notwithstanding the occurrence of one or more engine or ignition system faults which may impair the cylinder identification signal.

Abstract: An ignition secondary sensor is provided which is disposed in a high voltage path between an ignition coil and a spark plug for use with a detecting circuit for detecting ignition current and ion current flowing through a spark plug. The sensor comprises an ignition path connected in series with the high voltage path and having a pair of reverse current preventing diodes and a detection path connected to a spark plug side end portion of the ignition path and having a pair of current detecting diodes. A path portion of the detection path on the side of the current detecting diodes opposite to the ignition path and a path portion of the ignition path connecting between the reverse current preventing diodes are capacitively coupled. The detecting circuit is connected to the sensor for detecting the ignition current (ignition timing) on the basis of current flowing into the sensor therefrom and the ion current (combustion timing) on the basis of current flowing from the sensor thereinto.

Abstract: A digital degree wheel is provided including an engine sensor mounted to at least one of a camshaft, distributor and crankshaft of a vehicle for generating an activation signal after the detection of the rotation thereof. An ignition sensor connected to an ignition of the vehicle for generating a deactivation signal upon the detection of the advancing of the ignition of the vehicle. A display connected to the ignition sensor and the engine sensor for displaying a plurality of numeric digits representative of a timer, which is adapted to begin upon the receipt of the activation signal and further cease upon the receipt of the deactivation signal for setting and checking the ignition and valve timing of an engine of the vehicle.

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 engine comprises at least two combustion chambers and an ignition system having a spark device (11, 13) forming an electrode gap and a charging member (20) for accumulating the electrical energy necessary for generating a spark in the electrode gap. The combustion chambers are in the compression stroke according to a predetermined sequence. During a first engine revolution, high voltage pulses are supplied at a high frequency to all spark devices (11, 13). The spark voltage in the electrode gap of each spark device (11, 13) is measured for each spark. Based on the measured spark voltage of the different spark devices, the combustion chamber that first will be in the compression stroke is determined by means of an electronic control unit (3). Based on the predetermined sequence and the knowledge of the combustion chamber that first is in the compression stroke, fuel is injected in the combustion chamber that next will be in the compression stroke.

Abstract: A adjustable timing light including a housing having bottom portion and a top portion. The top portion of the housing is pivotally coupled to the bottom portion of the housing such that the top portion has a first orientation situated perpendicularly with respect to the bottom portion and a second orientation positioned in coaxial relationship therewith. Also included is a light assembly positioned within an interior space of the top portion of the housing. The light assembly is adapted to emit light toward a top face of the top portion of the housing upon the receipt of power. A plurality of wires are in electrical communication with the light assembly and a coil and a spark plug of a vehicle.

Abstract: A timing light for adjusting an engine's timing has a stroboscopic lamp for illuminating the timing marks and a trigger circuit for causing the stroboscopic lamp to illuminate the timing marks at a desired time. The trigger circuit has an input circuit receiving a signal representative of a spark plug firing; an output circuit providing a trigger signal to the stroboscopic lamp to cause the stroboscopic lamp to flash; and an anticipation circuit configured to determine when to provide the trigger signal to the stroboscopic lamp by establishing a trend in the rate of which the spark plug is firing so as to predict when a next trigger signal is to be provided by the output circuit. Establishment of the trend in the rate of which the spark plug is firing generally enhances the accuracy with which the engine's timing is measured.

Abstract: A preignition detecting method which prevents preignition (PI) from being misjudged as having occurred when an ignition plug is fouling. It is determined whether or not the ignition plug fouls in accordance with a voltage, developed across a detecting resistor which is fetched into a microcomputer 18 at a relatively early timing after an ignition command signal is outputted from an ignition device. Further it is determined whether or not preignition occurs in accordance with another voltage fetched at a relatively late timing after the ignition command signal is outputted. When it is determined that the ignition plug is fouling, it is inhibited to fetch the another voltage at a relatively late timing to prevent a misjudgment that preignition occurs due to a leakage current from being caused though preignition does not actually occur.

Abstract: An apparatus is provided for monitoring ignition in individual cylinders of a multi-cylinder engine of the type having an ignition system which includes a separate transformer for each cylinder. Each transformer has primary and secondary coils. The secondary coil is connected in series with a spark gap in an associated one of the cylinders. The ignition system further includes selector switches for receiving cylinder select signals and responsively connecting respective transformer primary coils. The current flows through the primary coil resulting in a voltage potential across an associated spark gap which normally increases to a magnitude sufficient to cause a spark across the spark gap. A first circuit receives the cylinder select signals, senses time delay between the reception of a cylinder select signal and sparking in a respective cylinder and responsively produces a delay signal indicative of the sensed time delay.

Abstract: A misfire detector for an internal combustion engine is provided which, if any of a plurality of modification factors is replaced by a value out of the proper range, can prevent erroneous misfire detection from, continuing.

Abstract: A cylinder identified apparatus for a multi-cylinder internal combustion engine can prevent abnormal or erroneous engine control based on misidentification of cylinders due misfiring, thus avoiding possible damage to the engine. A signal generator 108 generates a reference position signal L in synchronization with the rotation of the engine, the reference position signal L comprising a series of a specific pulse corresponding to a specific cylinder and remaining pulses corresponding to the remaining cylinders. Each pulse of the reference pulse signal L has a rising edge and a falling edge respectively corresponding to a first reference position and a second reference position of a piston in a corresponding cylinder. The rising edge of each specific pulse is angularly coincident with that of each remaining pulse, whereas the falling edge of each specific pulse is angularly offset from that of each remaining pulse.

Abstract: Ignition events in a direct ignition system are sensed by capacitively coupling positive and negative ignition voltages generated by the secondary winding of the ignition transformer. A pair of planar conductive plates disposed remote from each of the secondary winding leads capacitively couple the ignition voltages to a common node to provide an input to a processing circuit for determination of absolute engine position. The secondary coil and leads are at least partially immersed in an epoxy potting material, which forms a dielectric through which the conductive plates are capacitively coupled to the respective coil leads. The plates are electrically coupled by a conductor to form a common node, which in turn is electrically coupled to a signal processing circuit. Conveniently, the plates and conductors are formed as a single leadframe element and insert molded in the polyester material.

Abstract: In a device of estimating heat resistivity for a spark plug, an ignition spark control circuit is provided to discontinue ignition spark across electrodes of a spark plug at a predetermined intervals. A counter circuit is provided to count the times of the ignition spark suppressed by the ignition spark control circuit. A self-ignition detection circuit is provided to detect the self-ignition from the spark plug when the ignition spark is suppressed by the ignition spark control circuit. A self-ignition counter circuit is provided to count the numbers of the self-ignition detected by the self-ignition detection circuit. A calculation circuit is provided to calculate occurrences rate of the self-ignition from the spark plug on the basis of the suppressing numbers of the ignition spark counted by the counter circuit and the detecting numbers of the self-ignition counted by self-ignition counter circuit.

Abstract: An apparatus for determining the ignition characteristic of combustion in an internal combustion engine having an ignition coil including an ionic current computing circuit which analyzes ionic current enabled as a result of combustion. Ionic current flow is facilitated by establishing a voltage potential across the gap of a spark plug the instant after an ignition spark across the gap has occurred. The flow of ionic current enabled by the combustion process is provided to an ionic current computing circuit effecting the creation of a signal reflecting the flow of ionic current. The output signal from the computing circuit is integrated to determine the quality (length and magnitude of ionic current flow. This quality of flow is compared against predetermined high and low values for the integrated value and the ignition characteristic or state of combustion, ie, whether a spark and/or complete combustion has occurred, of the cylinder can be understood.

Abstract: The present invention is directed to an electrical circuit for detecting the presence of combustion within a catalytic converter preheater. Combustion of an air/fuel mixture within the preheater results in a wide-band high voltage RF signal across a spark plug gap disposed within the preheater, which is trapped by an ignition coil coupled to the spark plug for energizing the spark plug gap. The presence of combustion will effectuate an elimination or absorption of one or more specific frequencies within the RF voltage band. By coupling a combustion detection circuit comprising an inductor-capacitor (L-C) or resistor-inductor-capacitor (R-L-C) network between ground and a low voltage output terminal of a secondary winding of the ignition coil, and properly tuning the network components to one of the specific absorption frequencies, an output voltage of the combustion detection circuit during discharge of the spark plug will be responsive to the absence or presence of combustion in the burner.

Abstract: A Harley-Davidson motorcycle engine ignition timing device which electronically determines piston top dead center positioning and the degrees of spark plug ignition before or after TDC to permit dynamic setting and monitoring of the engine ignition timing.

Abstract: Absolute engine position sensing is provided by monitoring the temporal relationship of energization of multiple spark plugs sharing a common source of drive energy in a direct ignition application. The spark plugs are connected across the source with opposing electrical polarity, and the relative time of discharge across the plugs compared by sensing the time and polarity of high speed transient activity in proximity to the source.

Abstract: A sensor (10) detects misfires of combustion cylinders in an internal combustion engine by monitoring the exhaust from the engine. The sensor (10) comprises a spark gap (18) to be situated in exhaust from the engine and a transformer assembly (34). The transformer assembly (34) has an ignition transformer (41a) for providing a potential difference between the electrodes (18a, 18b) of the spark gap (18) and a detection transformer (41b) for sensing the occurrence of an arc across the spark gap (18). An ignition pulse shaper (68) provides an ignition pulse to the ignition transformer (41a) upon receiving a trigger signal from an engine control system (66), and a detection pulse shaper (72) monitors the detection transformer (41b) and forwards an arc detection signal to the engine control system (66) upon detecting an arc across the electrodes (18a, 18b) of the spark gap (18).

Abstract: A misfire-detecting system detects a misfire occurring in an internal combustion engine. A value of sparking voltage for discharging a spark plug of the engine is detected. A differentiating circuit differentiates the detected value of the sparking voltage. A misfire-determining circuit compares the differential value of the sparking voltage with a predetermined value, and determines, based upon a result of the comparison, whether a misfire has occurred in the engine.

Abstract: A device for generating a trigger signal from ignition pulses of an ignition system, in which each one of the ignition pulses occurring in the ignition system is represented regardless of whether the ignition process is suppressed or not. The device can be connected to an ignition system which has at least one ignition coil with a primary winding and at least one secondary winding, where the first terminal of the primary winding is connected to the first terminal of a voltage source and the second terminal of the primary winding is connected by means of a controllable switch with a second terminal of the voltage source.

Abstract: Methods and apparatus for detecting low impedance short circuits in a secondary winding circuit of a coil of a distributorless ignition system (DIS) by analyzing spark discharge signals on a primary winding of the ignition coil. In one embodiment, the duration times of the spark discharge signals are compared to a threshold spark duration time, with a low impedance short circuit being indicated if the threshold spark duration time is exceeded. In another embodiment, two or more spark dwell signals are applied to the primary of the ignition coil for each spark event of each associated pair of engine cylinders. A first or base time period is determined for the first dwell signal by measuring the time it takes the first dwell signal to produce a preselected current flow in the primary winding. A second time period is then determined by measuring the time it takes the second dwell signal to produce the same preselected current flow in the primary winding.

Abstract: A misfire-detecting system for an internal combustion engine detects a value of sparking voltage generated by the igniting device of the engine after generation of an ignition command signal, compares the value of the detected sparking voltage with a predetermined value, and determines whether or not a misfire has occurred in the engine, based upon the result of the comparison. The misfire-detecting system can discriminate between a misfire attributable to the fuel supply system of the engine and one attributable to the ignition system of the engine, from a detected peak value of the sparking voltage.

Abstract: Disclosed is an apparatus for detecting the reference rotational angle for each cylinder in a multiple-cylinder internal combustion engine, in which a reference pulse signal is output at a position of a predetermined rotational angle of the engine at a specific stroke of each cylinder synchronously with the revolution of the engine, a cylinder-discriminating pulse signal is put out just after termination of specific one of the reference pulse signal, the precedent and present values of elements, concerning the time, of the pulse signal are detected, and when the present value is smaller than the precedent value by at least a predetermined value, discrimination of cylinders is performed.

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: The firing time of a spark plug (22) is optimized by measuring its actual firing time (as by detecting the rise of current in the secondary winding (44) of an ignition coil (24)), comparing the actual firing time to the desired firing time, and advancing or retarding the turn-off time of current in the ignition coil's primary winding (42) to reduce any measured difference between the measured actual firing time and the desired firing time. The measurements can also be used to provide diagnostic information concerning the ignition system.

Abstract: An ignition adapter for DIS four stroke engines provides conventional voltage waveforms for a diagnostic oscilloscope. Spark plug leads from a DIS four stroke engine are grouped together depending on their respective firing polarity. A first signal pickup is placed around the spark plug leads from the spark plugs of one signal polarity, for example a positive signal polarity, and a second signal pickup is placed around the spark plug leads from the spark plugs of opposite polarity, for example a negative signal polarity. A trigger pickup is placed around the #1 cylinder spark plug lead. The voltage waveforms received in the signal pickups are applied to the ignition adapter, summed and displayed on the oscilloscope as a conventional voltage waveform. The polarity of the waveform can be reversed using a polarity switch. The waveform received in the trigger pickup is applied to the ignition adapter and compared to a reference voltage.

Abstract: Apparatus for setting the spark timing of an internal combustion engine comprising a pointer element removably attachable to rotor of a distributor with its cap removed and a scale element removably attachable to the exterior of the distributor housing in cooperative relationship with said pointer element to indicate the time of ignition spark impulse to an engine cylinder relative to the piston position in said cylinder.

Abstract: Ignition timing of an internal combustion engine of an automotive vehicle is automatically adjusted by idling the engine with a distributor whose coil terminal and spark plug terminals are disconnected from ignition circuit and detecting an spurious ignition signal for a specified cylinder from the distributor. The distributor is turned with respect to the engine through an angle in accordance with a difference between a rotated angle of the crankshaft of the engine from a detection of the spurious ignition signal to a provision of a top dead center signal and a predetermined angle of the crankshaft for an expected ignition timing.