Abstract: The present invention relates to a control device for a spark-ignition internal combustion engine provided with a cylinder pressure sensor and aims to facilitate optimal control of a combustion state even in a situation where an operating condition is variable. A predetermined combustion-related parameter whose value is uniquely determined by behavior of a change in cylinder pressure relative to a crank angle is used as a control value. Ignition timing is calculated based on the control value in accordance with a calculation rule determined according to a current or target operating condition of the internal combustion engine. The control value resulting from calculation based on a target value of a predetermined physical quantity relating to torque of the internal combustion engine in accordance with a predetermined calculation rule is used as a base value and is corrected by feeding back an output value of the cylinder pressure sensor.

Abstract: Methods and systems are provided for identifying and indicating degradation of an engine cylinder spark plug. In response to a cylinder misfire event during selected engine operating conditions, followed by an occurrence of a threshold number and/or rate of pre-ignition events in the same cylinder, a controller may determine that the spark plug is degraded. The controller may limit combustion in the cylinder in response to the degradation. Additionally, cylinder pre-ignition mitigating steps may be taken.

Abstract: A system and method for controlling a vehicle to implement an engine torque management strategy. The engine torque management strategy implements a sophisticated engine knock control method that alleviates/mitigates the cause of the knock while also optimizing vehicle performance and engine efficiency without compromising engine hardware protection. Whenever suitable, the system and method attempt to reduce the amount of air trapped in a knocking cylinder to reduce its effective compression ratio and to eliminate the knock while keeping the same optimal spark timing for combustion efficiency.

Abstract: A rotational fluctuation malfunction detection device for an internal combustion engine determines that fluctuations in output shaft rotational speed are “normal” when a rotational fluctuation value, obtained in a “disturbance fluctuation state” is below threshold L1. If rotational fluctuation value obtained in “disturbance fluctuation state” equals or exceeds L2, the rotational fluctuation malfunction detection device determines that the rotational fluctuation value is “abnormal.” However, when the rotational fluctuation value obtained in “disturbance fluctuation state” is equal to L1 or between L1 and L2, the rotational fluctuation malfunction detection device determines that the rotational fluctuation value is “normal” if the rotational fluctuation value obtained in the “non-disturbance state” is below L3, and the rotational fluctuation value is “abnormal” if the rotational fluctuation value obtained in the “non-disturbance state” equals or exceeds L3.

Abstract: A system for a vehicle includes a knock indication module, a valve control module, and a fault indication module. The knock indication module selectively indicates that knock occurred within a cylinder of an engine. The valve control module controls lifting of a valve of a cylinder of the engine and, in response to the knock indication module indicating that knock occurred within the cylinder, transitions lifting of the valve from one of a low lift state and a high lift state to the other one of the low lift state and the high lift state. The fault indication module selectively indicates that a fault is present in a variable valve lift (VVL) mechanism of the cylinder based on whether the knock indication module indicates that knock occurred within the cylinder after the transition to the other one of the low lift state and the high lift state.

Abstract: A method for operating an internal combustion engine, in particular a gas engine having at least two cylinders, includes acquiring a cylinder-specific first cylinder signal (pmax, E) from each cylinder. At least one combustion parameter (Q, Z) of the corresponding cylinder is controlled as a function of the first cylinder signal (pmax, E), and a cylinder-specific reference cylinder value (pmax?, E?) is set for the first cylinder signal (pmax, E) for each cylinder. The at least one combustion parameter (Q, Z) of the cylinder is adjusted as a function of the deviation of the first cylinder signal (pmax, E) from the reference cylinder value (pmax?, E?), and the first cylinder signal (pmax, E) tracks the reference cylinder value (pmax?, E?).

Abstract: A hybrid powertrain includes a combustion engine, an electric machine arrangement, a gearbox operable to receive motive power from at least one of the combustion engine and the electric machine arrangement for providing motive power to a load of the powertrain. The powertrain is configurable in operation so that its combustion engine is switchable between an inactive state and an active state. The combustion engine is cranked to switch it from its inactive state to its active state. Application of cranking torque to the combustion engine is controlled in operation to substantially temporally coincide with a gear change in the gearbox.

Abstract: Systems and methods for identifying alcohol content of a fuel in an engine. In one example approach, a method comprises adjusting fuel injection to the engine based on fuel alcohol content identified from crankshaft acceleration. For example, the crankshaft acceleration may be generated by modulating an air/fuel ratio in a selected cylinder across a range of air/fuel ratios while keeping the engine at stoichiometry.

Abstract: When a maximum value of vibration intensity (maximum vibration intensity)(Vmax) acquired from a vibration sensor (33) in a low engine speed/high engine load (operating region (R)) is equal to or greater than a given threshold value (X), a spark timing of a spark plug (16) is shifted from a point set in a normal state on a retard side with respect to a compression top dead center, farther toward the retard side. Then, when a maximum vibration intensity (Vmax2) acquired after the spark timing retard is greater than a maximum vibration intensity (Vmax1) acquired before the spark timing retard, it is determined that preignition occurs. This technique makes it possible to reliably detect preignition using the vibration sensor, while distinguishing the preignition from knocking. An in-cylinder pressure sensor for detecting an in-cylinder pressure of an engine may be used to determine the presence or absence of the preignition, in the same manner.

Abstract: A control device of an internal combustion engine includes a filter processing portion which performs a filter processing on the vibration level extracted by the vibration level extraction portion, and calculates a vibration level after the filter processing; and an abnormal ignition suppression control portion which compares the vibration level after the filter processing to the abnormal ignition determination value when a retard correction equal to or greater than a predetermined value is performed by the knock control portion, in a case where it is determined that the vibration level after the filter processing is equal to or greater than the abnormal ignition determination value, determines that the abnormal ignition is generated in the internal combustion engine, corrects and controls the combustion control portion in a direction of suppressing the abnormal ignition.

Abstract: Methods and systems are provided for identifying and differentiating knock and pre-ignition using a plurality of knock sensors distributed along an engine block. By dynamically adjusting cylinder-specific assignment of the knock sensors for knock detection and pre-ignition detection based on operating conditions of each cylinder, knock and pre-ignition is more reliably identified and distinguished.

Abstract: A method for driveline impact reverberation reduction including operating an engine coupled to a transmission; regulating operation of the engine with a controller to adjust fueling of the engine which includes providing a signal to the controller representative of a requested engine torque; determining a first fueling rate as a function of the signal and a set of preselected operating instructions; adjusting a set of engine operating parameters according to the first fueling rate; determining a second fueling rate as a function of the first fueling rate; and adjusting a set of engine operating conditions according to the second fueling rate.

Abstract: An ignition timing control system for an internal combustion engine, for controlling an ignition timing of the engine, is provided. A charging efficiency of the engine is calculated according to the intake air flow rate and the engine rotational speed which are detected, and a knock limit ignition timing is calculated according to the engine rotational speed and the charging efficiency. A knock correction value is calculated according to the knocking detection result by a knock sensor, and a learning parameter table, in which first and second learning parameters are set, is updated based on the engine rotational speed and the knock correction value when the knocking is detected. The learning parameter table is retrieved according to the engine rotational speed, to calculate the first and second learning parameters.

Abstract: A hybrid powertrain includes a combustion engine, an electric machine arrangement, a gearbox operable to receive motive power from at least one of the combustion engine and the electric machine arrangement for providing motive power to a load of the powertrain. The powertrain is configurable in operation so that its combustion engine is switchable between an inactive state and an active state. The combustion engine is cranked to switch it from its inactive state to its active state. Application of cranking torque to the combustion engine is controlled in operation to substantially temporally coincide with a gear change in the gearbox.

Abstract: A method for knock detection in an internal combustion engine in which a fuel/air mixture is ignited by means of a corona discharge. To generate the corona discharge, an electrical resonant circuit is excited, in which an ignition electrode that is electrically insulated with respect to combustion chamber walls constitutes a capacitor together with the combustion chamber walls. For knock detection, an electrical variable of the resonant circuit is measured and the course thereof is evaluated. The course of the electrical variable is checked to determine whether it has a local extremum after the start of the fuel combustion.

Abstract: A number of systems and methods are disclosed which increase the replenishment interval for anti-knock fluid. This is especially important during activities which require a large amount of anti-knock fluid, such as towing. In some embodiments, the systems and methods are used to reduce anti-knock fluid consumption. For example, changes to engine operation, such as rich operation, spark retarding, upspeeding, and variable valve timing, all serve to reduce the amount of anti-knock fluid required to eliminate knocking. In other embodiments, the composition of the anti-knock fluid is modified, such as by using a higher octane fluid, or through the addition of water to the anti-knock fluid. In other embodiments, the replenishment interval is increased through a larger anti-knock fluid storage capacity. In one embodiment, a three tank system is used where the third tank can be used to store gasoline or anti-knock fluid, depending on the driving conditions.

Abstract: An ACM_ECU (200) estimates an engine vibration state in a first cycle (C1) of engine vibration on the basis of signal outputs from a TDC sensor (Sb) and a crank pulse sensor (Sa) and calculates a target current value waveform having a cycle length (T1). The ACM_ECU (200) then samples the target current value waveform at a constant sampling rate, thereby obtaining, for example, an aggregate of the data of target current values (Fr_ICMD) for a driving unit for driving an active control mount (MF) on the front side (Fr side). After that, the ACM_ECU (200) estimates the cycle length (T3?) of a third cycle (C3) of the engine vibration on the basis of a predetermined number of crank pulse intervals at a timing when the data of the target current values (Fr_ICMD) are output to the driving unit (41). The obtained aggregate of the data of target current values is corrected so as to correspond to the estimated cycle length (T3?) and fed to the driving unit (41).

Abstract: In a method for operating an internal combustion engine, a computer program product, a computer program, and a control and/or regulation device for the internal combustion engine, the internal combustion engine is allowed to be operated using an enriched air/fuel mixture, without exceeding a rich combustion limit of the internal combustion engine. In the process, a setpoint value for a variable characterizing the air/fuel mixture is specified in at least one operating state of the internal combustion engine. A value of at least one variable characterizing the quality of combustion is determined. The determined value for the at least one variable characterizing the quality of combustion is compared to a first specified threshold value. If the determined value for the at least one variable characterizing the quality of combustion deviates from the first specified threshold value by an amount that exceeds a second specified threshold value, then the setpoint value is corrected.

Abstract: A combustion state control device for an internal combustion engine includes an abnormal combustion detecting unit for detecting abnormal combustion of the internal combustion engine, a fuel supply cut-off unit for cutting off a fuel supply to a cylinder where the abnormal combustion is detected during a cycle from an intake stroke of the cylinder to a next intake stroke thereof, when the abnormal combustion detecting unit detects the abnormal combustion of a cylinder, a vehicle vibration detecting unit for detecting vibration of a vehicle, and a fuel supply cut-off ending unit for ending cutting off of the fuel supply when the vehicle vibration detecting unit detects the vibration of the vehicle while the fuel supply is being cut off.

Abstract: The present invention provides for predicting peak cylinder temperatures above which knock in an engine may become more frequent and then provides one or more actuation approaches to reduce the knock of the engine while maintaining engine performance. The actuation approaches of the present invention include one or more of direct injection, engine gas recirculation, and spark retarding, where the application of one or more the actuation approaches is determined based upon using operational and engine characteristic inputs as well as modeling and estimation values as inputs in a feedforward control methodology.

Abstract: A method and a control module that includes a filter coefficient determination module that generates filter coefficients based upon an engine operating conditions. The control module includes a filter module that filters the in-cylinder pressure signal with a filter having the filter coefficients to form a filtered pressure signal and an engine control module that controls the engine using the filtered pressure signal.

Abstract: A method for recognizing irregular combustion in an internal combustion engine includes supplying fuel directly to a combustion chamber of a cylinder of the internal combustion engine using an injector. The injector is connected to a fuel supply line that includes a pressure sensor configured to measure pressure in the fuel supply line. The pressure in the fuel supply line is measured during the supply of fuel into the combustion chamber. It is then ascertaining whether irregular combustion is occurring based on the measured pressure in the fuel supply line.

Abstract: Methods and systems are provided for improving fuel usage while addressing knock by adjusting the use of spark retard and direct injection of a knock control fluid based on engine operating conditions and the composition of the injected fluid. One or more engine parameters, such as EGR, VCT, boost, throttle position, and CMCV, are coordinated with the direct injection to reduce torque and EGR transients.

Abstract: A self power circuit for ion sense circuitry is provided. The self power circuit is configured to supply the voltages required to generate and measure an ion current flow in a combustion chamber of an engine. The power circuit stores power from the current flow in the ignition coil secondary circuit during at least a portion of a sparking period for use during the ion current measurement period between sparking events. Ion current generation voltage as well as positive and negative sensor circuit power supply voltages are generated in one embodiment.

Abstract: An acceleration-based method and device for the safety monitoring of a drive is provided. In the method a setpoint torque is calculated in a safety function as a function of the position of the accelerator pedal. An expected vehicle acceleration is determined, as a function of the setpoint torque, in the safety function. An actual vehicle acceleration is determined, preferably by an acceleration sensor. A fault situation may be detected by comparing the actual vehicle acceleration and the expected vehicle acceleration. A device, preferably included in the vehicle electronics, is configured to implement the acceleration-based method.

Abstract: In a method for determining a vibration-optimised adjustment of an injection device of an internal combustion engine, for each cycle of the internal combustion engine, a plurality of individual injections per cylinder is carried out by the injection device, each of which is defined by a relative injection moment and an individual injection quantity. A temporal course of a resulting pressure influenced by pressure waves is determined in a fuel guiding part, and the above-mentioned adjustment is determined by variation of the injection moment of at least one individual injection and/or the individual quantity, such that the adjustment is characterized by a temporal variation of the resulting pressure, which is reduced by an at least partially destructive interference between the cited pressure waves. A corresponding device can determine a vibration-optimised adjustment of an injection device, and an internal combustion engine may have such a device.

Abstract: An internal combustion engine knock controlling apparatus is obtained that improves knock detection performance by making a correction period appropriate without performing matching, when calculating a transition correction factor for correcting a filter coefficient used for calculating a mean value and a standard deviation of a knock signal in a transitional operation state. A previous value of a filter coefficient for calculating a knock determination threshold value that has been corrected by a transition correction factor is used for a filter coefficient for calculating the transition correction factor so that the response characteristics are made equal between a filtering process used for calculating a transition correction factor for correcting a knock determination threshold value and a filtering process used for calculating the knock determination threshold value in a transition operation period.

Abstract: A control system includes a cylinder pressure sensor (CPS) that senses a cylinder pressure of an engine and generates a CPS signal based on the cylinder pressure. A CPS failure detection module selectively generates a failure signal based on characteristics of the CPS signal in a knock frequency range. A status detection module generates a CPS status signal based on the CPS signal and the failure signal.

Abstract: An A/D conversion device includes a first A/D converter that receives an analog vibration signal corresponding to a vibration detected by a vibration detecting sensor and converts the analog vibration signal to a first digital value, an analog amplifier that amplifies the analog vibration signal and outputs an amplified signal, a second A/D converter that converts the amplified signal to a second digital value, a determiner that determines whether an amplitude of the amplified signal input to the second A/D converter exceeds a range of amplitude that is convertible by the second A/D converter, and a selector that receives the first digital value and the second digital value and output one of the first and second digital values based on the determination of the determiner.

Abstract: A method for recognizing pre-ignitions in a gasoline engine which occur in the combustion chamber of the gasoline engine, independently of the ignition of a fuel-air mixture by a spark plug. In a method which reliably recognizes the formation of sporadically imminent pre-ignitions, a combustion chamber pressure which occurs prior or subsequent to the ignition point of the spark plug is evaluated for determining the pre-ignition.

Abstract: A method for closed-loop combustion control within an internal combustion engine, that includes, but is not limited to individual calculation of actual Start of Combustion (SoC) information for all cylinders of said internal combustion engine using information from a combustion sensor applied to the engine, calculation of 50% Mass Fraction Burned (MFB50) and SoC information using cylinder pressure sensor information available from at least one leading cylinder of the engine, using pressure-based MFB50 information from the at least one leading cylinder to control it in closed loop, and using pressure-based SoC information from said at least one leading cylinder as a reference value for comparison with the combustion sensor based value of SoC from the same cylinder in order to calculate the desired SoC for the other cylinders of the engine which are then controlled relative to said at least one leading cylinder.

Abstract: An ignition timing controller for an engine includes basic knock-limit ignition timing calculation means that calculates a basic knock-limit ignition timing on the basis of an operating state of the engine; learning-region variation calculation means that learns the knock-limit ignition timing of the engine in two operating regions and thereby calculates a learning-region variation due to octane number and a learning-region variation due to humidity in one of the operating regions; estimated variation calculation means that estimates a variation due to octane number and a variation due to humidity in a present operating state on the basis of the learning-region variation due to octane number and the learning-region variation due to humidity; and knock-limit ignition timing calculation means that calculates the knock-limit ignition timing in the present operating state on the basis of the basic knock-limit ignition timing, the variation due to octane number, and the variation due to humidity.

Abstract: A control system for a vehicle is provided. The control system includes a signal processing module that receives a sensor signal and extracts a plurality of sample points from the sensor signal. A computation module computes a summation of the sample points, computes a summation of squares of the sample points, and computes a standard deviation based on the summation of the sample points and the summation of the squares of the sample points. A control module generates a control signal based on the sensor signal and the standard deviation.

Abstract: In a knock control device of an internal combustion engine equipped with a control unit which updates a background level based on an output signal from a knock sensor and detects the generation of a knock by comparing a variation of the background level with a knock determination value, a determination as to whether the knock is generated is performed by ((variation of first filter value of peak hold value)>((1?filter coefficient)/(1+filter coefficient)×(predetermined value larger than maximum value of variation of peak hold value in case where knock is not generated))).

Abstract: In an operating method for a direct-injection gasoline internal combustion engine having a plurality of combustion chambers with at least partially low-NOx combustion (NAV) and a plurality of partial operating modes with at least one partial operating mode having controlled auto-ignition (RZV), a reduction in the reactivity of exhaust gas recirculated into the respective combustion chamber is achieved by means of an external exhaust gas recirculation using exhaust gas which has been conducted through an oxidation catalyst thereby improving the operating stability of the engine particularly in the auto-ignition partial operating mode.

Abstract: A method for controlling combustion in a direct injection internal combustion engine operable in a lean combustion mode includes monitoring in-cylinder pressure, utilizing a time-based filter to calculate an actual combustion noise based upon the monitored in-cylinder pressure, monitoring combustion control parameters utilized by the engine, determining an expected combustion noise based upon the monitored combustion control parameters, comparing the actual combustion noise to the expected combustion noise, and adjusting the combustion control parameters based upon the comparing.

Abstract: The apparatus according to the invention comprises a controller for forming a speed signal arranged to receive speed measurement data of the internal combustion engine as well as speed reference data. The apparatus additionally comprises a module for forming the internal speed reference value instead of the speed reference value set to be used when forming the control signal.

Abstract: A microcomputer is formed of a CPU and a detection circuit and inputs sensor signals of a vibration sensor and a rotation sensor. The detection circuit includes an AD converter circuit for AD conversion of the sensor signal of the vibration sensor at a predetermined sampling interval, a peak hold circuit for detecting a peak value of the sensor signal, a RAM for storing the peak value, a counter for detecting a crank angle at a peak value detection time, and an angle calculation part. The microcomputer divides a pre-ignition check interval into plural interval units and checks the pre-ignition based on the peak value detected in each unit interval. The pre-ignition and the knock are checked by using different threshold values in an interval, in which the pre-ignition check interval overlaps a knock check interval.

Abstract: Methods and systems are provided for improving fuel usage while addressing knock by adjusting the use of spark retard and direct injection of a fluid based on engine operating conditions and the composition of the injected fluid. One or more engine parameters, such as EGR, VCT, boost, throttle position, are coordinated with the direct injection to reduce torque and EGR transients.

Abstract: A method of actively controlling pattern factor in a gas turbine engine includes the steps of issuing fuel into a combustion chamber of a gas turbine engine through one or more circumferentially disposed fuel injectors, determining an initial circumferential pattern factor in the combustion chamber, and adjusting fuel flow through one or more selected fuel injectors based on the initial circumferential pattern factor, to yield a modified circumferential pattern factor in the combustion chamber. The step of determining the circumferential pattern factor can include the steps of detecting a chemiluminescent signature within the combustor, correlating the chemiluminescent signature to an equivalence ratio, and computing the initial circumferential pattern factor based on the equivalence ratio.

Abstract: A method to calibrate the fuel injection in at least one combustion chamber of a Diesel engine includes: a) recording the combustion noise power or amplitude in the combustion chamber over a piston position range [?1i;?2i], b) at the same time, recording the piston position during the same piston position range [?1i;?2i], c) determining from the preceding recordings for which piston position Kmin-i the measured combustion noise power passes through a minimum Pmin-i when the piston moves from position ?1i to position ?2i, d) adjusting the fuel injection according to the determined piston position Kmin-i.

Abstract: An ON-ignition signal is outputted from an ignition control portion in a period from a posterior time point of the power stroke to an valve opening timing of an exhaust valve so that a capacitor is charged. Then, when it is determined that the maximum value of an ion-output value detected during a negative valve overlap period becomes greater than or equal to a threshold, it is determined that the applied voltage between an center electrode and a ground electrode of a spark plug is dropped. The ON-ignition signal is outputted again to charge the capacitor before the intake valve is opened.

Abstract: A knock detection system for an engine includes an intensity module, a knock threshold module, and a detection module. The intensity module determines an engine vibration intensity during a first period of engine operation. The knock threshold module determines a knock threshold based on an ethanol concentration in a fuel supplied to the engine. The detection module determines whether engine knock has occurred during the first period by comparing the knock threshold and the engine vibration intensity.

Abstract: A knock control apparatus for an internal combustion engine includes a knock signal normalization portion that normalizes a knock signal using base statistics calculated on the basis of the knock signal. The knock signal normalization portion calculates base statistics on the basis of a last value and a current value of the knock signal and normalizes the knock signal using a base statistic interpolated according to an operating state.

Abstract: The invention relates to a method for setting an emergency operational mode in a system which detects pre-ignitions in a combustion engine and which contains errors. The system consists of at least one sensor (17) and/or at least one sensor cable (24) and/or a sensor signal evaluation device (20), and is subject to a diagnosis to detect an error. In order to prevent damage to the combustion engine if the system for detecting pre-ignitions does contain an error, a standard path (26), which comprises sensor signal capturing, sensor signal evaluation, detection of pre-ignitions and initiation of measures to counter the pre-ignitions, is interrupted when the diagnosis detects an error in the system (17, 24, 29), and a safety path (27) is activated as an emergency operational mode.

Abstract: An engine control system includes a determination module and a detection module. The determination module, based on an engine vibration signal generated by an engine vibration sensor, determines a frequency of engine vibration and determines a crankshaft position corresponding to the engine vibration. The detection module detects engine oil aeration and starvation when the frequency and crankshaft position are greater than predetermined thresholds, respectively.

Abstract: A method of controlling combustion of a diesel engine may include a vibration measuring step of measuring engine vibrations, a measurement region setting step of setting a range where an LPP (location of peak pressure) is predicted from measured vibration data, a frequency transforming step of transforming a vibration signal to a frequency response function, a frequency integrating step of integrating the transformed frequency response function, an LPP detecting step of selecting a location of peak pressure from integrated frequency response function, an estimated value determining step of selecting LPP offset and SOC (start of combustion) offset by using the detected LPP, an error determining step of determining LPP value error and SOC value error by comparing the estimated LPP value and the estimated SOC value with a target LPP value and a target SOC value, and a combustion correcting step of correcting and controlling combustion by the determined errors.

Abstract: There are provided a combustion start determination unit that determines whether or not the inner-cylinder state of an internal combustion engine has changed from a non-combustion state to a combustion state; and a filter coefficient changing demand unit that outputs a filter coefficient changing demand until a predetermined filter coefficient changing period elapses from the time instant when the combustion start determination unit determines that the inner-cylinder state of the internal combustion engine has changed from the non-combustion state to the combustion state to the time instant. Based on the filter coefficient changing demand, at least one of a background level calculation unit and a standard deviation calculation unit changes the value of a filter coefficient utilized in a filtering operation to the one with which a filtering effect is weakened.

Abstract: An internal combustion engine control apparatus includes a pseudo knock determination unit that determines whether or not a pseudo knock has been produced in a knock detection window, based on at least one of the frequency, a status amount indicating a rotation speed of the internal combustion engine, a status amount indicating a load of the internal combustion engine, and a status amount indicating an air-fuel ratio of the internal combustion engine; and a moving-average processing unit that sets a second period to a period that is approximately the same as a first period, in the case where it has been determined that the pseudo knock was not produced, and that does not implement moving-averaging or sets the second period to a period that is narrower than the first period, in the case where it has been determined that a pseudo knock was produced.

Abstract: Methods and systems are provided for mitigating engine pre-ignition based on a feed-forward likelihood of pre-ignition and feedback from a pre-ignition event. In response to an indication of pre-ignition, a cylinder may be enriched while an engine load is limited. The enrichment may be followed by an enleanment to restore exhaust catalyst feed-gas oxygen levels. The mitigating steps may be adjusted based on engine operating conditions, a pre-ignition count, as well as the nature of the pre-ignition.