DE102015108864A1 - A method and system for a spark ignition engine - Google Patents

Abstract

A method for a spark-ignition internal combustion engine comprises: energizing a common ignition coil (10, 20) to simultaneously actuate a first spark event on a first spark plug (11) coupled to a first cylinder of the engine and a second spark event on a second spark plug (12) coupled to a second cylinder of the engine, wherein the engine is configured so that, in a given ignition coil excitation, the spark event in only the first or second cylinder serves to initiate combustion while the spark event in the other of first and second cylinders is wasted; and selectively retarding intake valve opening and / or fuel injection for the other from the first and second cylinders to prevent backfire into an intake manifold of the engine.

Description

The present disclosure relates to a method and system for a spark-ignition engine, and more particularly, but not exclusively, to a method and system for preventing kickback events in the intake.

background

Internal combustion engines typically include intake valves and exhaust valves for controlling the flow of gases into and out of the combustion chamber. The performance of the internal combustion engine is determined, at least in part, by the control of the opening and closing times of the valves and the degree to which the valves are opened. Typically, the opening and closing of the valves is determined by camshafts that are limited to rotate at a fixed speed ratio to the engine crankshaft. In such a system, the relative valve timing must be the same for all engine speeds and conditions and, as a result, compromises are required. However, to overcome this limitation, the engine may be provided with a variable valve timing actuation system and / or a variable valve lift actuation system, whereby performance over the entire operating range of the engine may be improved.

Regardless of whether or not a variable valve actuation system is provided, there may be a time during which both the intake valve and the exhaust valve are open simultaneously. In particular, the valves may be controlled to open the intake valve just before the piston reaches top dead center (TDC) on the exhaust stroke. Similarly, the exhaust valve may be controlled to close shortly after the piston begins to descend on the intake stroke. Such an overlap in the opening of the valves can cause a siphon effect in which the exhaust gas stream draws additional charge air into the combustion chamber. In a variable valve actuation system, this siphon effect can be adjusted over the operating range of the engine.

In addition to the valve overlap described above, early intake valve opening can reduce emissions. Early opening of the intake valve may cause part of the inert exhaust gas to flow out of the cylinder via the intake valve, allowing it to cool in the intake manifold. This inert gas may then enter the cylinder during a subsequent intake stroke, which helps to control the temperature of the cylinder and thus also the nitrogen oxide emissions. Again, this effect can be adjusted in a variable valve actuation system over the operating range of the engine.

In addition, Wasted Spark Ignition systems are commonly encountered in spark-ignition four-stroke engines. These systems take advantage of the fact that the exhaust stroke and the compression stroke in cylinder pairs are coordinated. In such a system, an ignition coil can supply two spark plugs, which are fired simultaneously at the time required by the cylinder filled with fuel, so that the spark in the other cylinder is wasted. Such ignition systems are desirable because they reduce the number of ignition coils required.

The inventors of the present disclosure have found that in a variable valve actuation system that can take advantage of the intake valve opening scenarios described above, there can be a significant overlap between a wasted spark event and the beginning of the intake stroke. In intake manifold injection systems, emission limitations often result in fuel injection while the intake valve is still closed. As a result, when the intake valve is opened and the "wasted" spark occurs, an ignitable mixture may be present in the cylinder, and the flame may spread in the direction of the intake manifold, e.g. B. strike back.

Information on the invention

According to a first aspect of the present disclosure, a method for a spark-ignition internal combustion engine is provided, the method comprising:
Energizing a common ignition coil for simultaneously actuating a first spark event on a first spark plug coupled to a first cylinder of the engine and a second spark event on a second spark plug coupled to a second cylinder of the engine, the engine configured in that, for a given ignition coil excitation, the spark event in only one of the first and second cylinders serves to initiate combustion while the spark event in the other of the first and second cylinders is wasted; and
selectively delaying intake valve opening and / or fuel injection for the other of the first and second cylinders to prevent backfire into an intake manifold of the engine.

The method may further include adjusting the ignition coil excitation based on the operating conditions of the engine. The operating conditions may include one or more of intake charge temperature, fuel octane number, engine speed, and intake manifold pressure.

The method may further include determining the scheduled intake valve lift for the other of the first and second cylinders during the spark event. The method may further include delaying intake valve opening and / or fuel injection for the other of the first and second cylinders when the scheduled intake valve lift at the spark event for the other of the first and second cylinders is greater than or equal to a maximum tolerated intake valve lift for the other the first and second cylinders at the spark event.

The method may further include determining the maximum tolerated intake valve lift for the other of the first and second cylinders during the spark event. The maximum tolerated intake valve lift during the spark event may be a fixed value, e.g. Zero, or it may be a function of the scheduled occurrence of the spark event.

The method may further include delaying the intake valve opening such that the intake valve lift for the other of the first and second cylinders in the spark event is equal to or less than the maximum tolerated intake valve lift for the other of the first and second cylinders in the spark event. Alternatively or additionally, the method may further include delaying fuel injection so that not all of the fuel to be injected is in the other of the first and second cylinders when the spark event occurs. For example, the method may further include delaying the fuel injection so that the fuel arrives in the cylinder after the wasted spark event has occurred.

The method may further include determining a likelihood of a backfire into the intake manifold of the engine based on the timing of the ignition coil energization and the intake valve control.

The method may further comprise determining whether to open the intake valve and / or retard fuel injection for the other of the first and second cylinders. The method may further include adjusting the length of the delay of the intake valve opening and / or the fuel injection as a function of the timing of the ignition coil energization. The method may further include performing the determination of whether to open the intake valve and / or retard fuel injection for the other of the first and second cylinders while the engine is operating.

The method may further include limiting the opening of the intake valve to the other of the first and second cylinders when the spark event occurs after the first and second crank pins associated with the first and second cylinders pass top dead center (TDC). The method may further include limiting intake valve opening for the other of the first and second cylinders when the spark event occurs after the first and second crank pins associated with the first and second cylinders pass the TDC to an amount that is smaller is as if the spark event occurred before the first and second crank pins pass the TDC.

The method may further include limiting inlet valve opening to a value that is less than or equal to 1 mm (e.g., about 1 mm), e.g. When the spark event in the other of the first and second cylinders occurs after the first and second crank pins associated with the first and second cylinders pass the top dead center. The method may further include limiting intake valve opening to a value greater than 1 mm (eg, greater than about 1 mm), e.g. When the spark event in the other of the first and second cylinders occurs before the first and second crank pins associated with the first and second cylinders pass top dead center. (The value of the intake valve opening may correspond to a distance between a valve closing and an associated valve seat, in other words, the gap between the valve closing and the valve seat.)

For the particular ignition coil excitation, a first piston in the first cylinder may be in a compression stroke, and a second piston in the second cylinder may be in a power stroke. In other words, the first and second crankpins associated with the first and second pistons may be tuned, although the first and second pistons may perform different strokes of an engine cycle, such as a four-stroke cycle.

For a subsequent ignition coil excitation, it may be intended that the spark event in the other of the first and second cylinders cause combustion and that the spark event in the first or second spark event may be wasted. The method may further include selectively retarding intake valve opening and / or include the fuel injection for the first or second cylinder to prevent a rebound into the intake manifold of the engine.

The method may further include energizing a further common ignition coil for simultaneously actuating a third spark event on a third spark plug coupled to a third cylinder of the engine and a fourth spark event on a fourth spark plug coupled to a fourth cylinder of the engine. include. The engine may be configured such that, for a particular excitation of the further ignition coil, it is intended that the spark event in just one of the third and fourth cylinders should initiate combustion while the spark event in the other is wasted from the third and fourth cylinders. The method may further include selectively delaying opening of an intake valve and / or fuel injection for the other of the third and fourth cylinders to prevent backfire into the intake manifold of the engine.

According to a second aspect of the present disclosure, there is provided an engine ignition system for a spark-ignition internal combustion engine, the engine comprising:
a first spark plug for triggering a first spark event in a first cylinder of the engine;
a second spark plug for triggering a second spark event in a second cylinder of the engine;
a common ignition coil coupled to both the first and second spark plugs;
wherein the engine ignition system includes one or more engine controls configured to activate the ignition coil to simultaneously energize both the first and second spark plugs so that the first and second spark events occur simultaneously; such that in a given ignition coil excitation, the spark event in only the first or second cylinder is intended to initiate combustion, the spark event in the other being wasted from the first and second cylinders; and
wherein the engine controls are further configured to selectively open an intake valve and / or retard fuel injection for the other of the first and second cylinders to prevent backfire into an intake manifold of the engine.

The engine ignition system may further include the first and second spark plugs and / or the common ignition coil. The engine may further include the intake valve and / or a fuel injection valve. The fuel injector may inject fuel into an intake manifold in the region of the intake valve.

The one or more controllers may be further configured to perform any of the above-mentioned methods. An engine control unit may comprise, at least in part, the above-mentioned controls.

Software, when executed on a computing device, may cause the computing device to perform any of the above-mentioned methods. The one or more engine controllers may be provided with computer readable instructions stored on a nonvolatile memory for performing any of the above mentioned methods.

A vehicle or engine may include the aforementioned engine ignition system for a spark-ignition internal combustion engine.

Brief description of the drawings

For a better understanding of the present disclosure and to more clearly show how it may be carried into effect, the attached exemplary drawings are explained in which:

1 shows an engine ignition system for a spark-ignition internal combustion engine according to examples of the present disclosure;

2 shows a method for a spark-ignition internal combustion engine according to examples of the present disclosure;

3 FIG. 13 is a graph showing how the intake valve lift may vary with the crank angle and the delayed intake valve lift according to a first example of the present disclosure; FIG.

4 Fig. 12 is a diagram showing how the intake valve lift may be varied in response to the timing of the spark event; and

5 FIG. 12 is a graph showing how the intake valve lift with the crank angle and the retarded fuel injection may vary according to a second example of the present disclosure.

Detailed description

Referring to 1 The present disclosure refers to Kraftmaschinenzündsystem 100 for an internal combustion engine with spark ignition. The engine includes a common ignition coil 10 electrically connected to a first and a second spark plug 11 . 12 is coupled. The first spark plug 11 may trigger a first spark event in a first cylinder of the engine. Similarly, the second spark plug 12 trigger a second spark event in a second cylinder of the engine.

The engine ignition system 100 can be an engine controller 30 include. The engine control 30 may include one or more modules for controlling the engine. In particular, the engine control 30 be designed to the common ignition coil 10 to activate with the first and second spark plugs 11 . 12 is coupled. For example, the engine control 30 specifically a battery 40 with the common ignition coil 10 connect. Accordingly, the engine control 30 over the common ignition coil 10 at the same time both the first and the second spark plug 11 . 12 so that the first and second spark events occur simultaneously. The engine may operate in a mode in which it is intended that at a certain point in the engine cycle, either the first or the second spark event result in a combustion event. On the other hand, it may not be intended that the other of the first and second spark events in the respective cylinder will result in a combustion event, so that it may be wasted. At a subsequent point in the engine cycle, the combustion event and wasted spark event may swap the cylinders. It will be appreciated that the first and second pistons may operate in the respective first and second cylinders in a four-stroke mode with the first and second pistons moving together but at different strokes of the cycle.

Still referring to 1 For example, the engine may have another common ignition coil 20 which electrically connect with the third and fourth spark plugs 21 . 22 is coupled. The third spark plug 21 may trigger a third spark event in a third cylinder of the engine. Similarly, the fourth spark plug 22 trigger a fourth spark event in a fourth cylinder of the engine. As with the common ignition coil 10 can the more common ignition coil 20 at the same time both the third and the fourth spark plug 21 . 22 so that the third and fourth spark events occur simultaneously. The other common ignition coil 20 can through the engine control 30 to be activated, which specifically targets the battery 40 with the other common ignition coil 20 can connect. It may be intended that only one of the third and fourth spark events in the respective cylinder triggers combustion. It may not be intended that the other of the third and fourth spark events in the respective cylinder will initiate combustion, so it may be wasted. The combustion event and wasted spark event may swap the cylinders upon subsequent ignition coil energization. The third and fourth pistons in the third and fourth cylinders may also operate in a four-stroke cycle with the third and fourth pistons moving together but in different strokes of the cylinder.

It is understood that the first, second, third and fourth pistons and the respective cylinders may form a four-cylinder engine, each piston being arranged to perform a different stroke of the cylinder than there would be intake stroke, compression stroke, Working stroke and exhaust stroke (eg expansion stroke). The first and second pistons may be out of phase with the third and fourth pistons. In other words, the first and second pistons may be connected to the crankshaft at a point that is 180 ° from the point on the crankshaft to which the third and fourth pistons are connected. Although described for an engine with four pistons, it should be understood that other pistons and cylinders may be provided.

The engine control 30 or at least one engine control module 30 may be configured to selectively delay the opening of an intake valve for a cylinder in which a wasted spark event is taking place. Alternatively or additionally, the engine control 30 or at least one module thereof may be configured to selectively retard the injection of fuel into a cylinder or suction port of the cylinder in which a wasted spark event is taking place. Delaying intake valve opening or injecting fuel may reduce the likelihood that the wasted spark event will initiate combustion.

Referring to 2 is now a procedure 200 for a spark-ignition internal combustion engine according to an example of the present disclosure. The procedure 200 can be performed with respect to a cylinder in which the occurrence of a wasted spark event is planned. The procedure 200 can be executed for every wasted spark event in each cylinder, or the procedure 200 can be performed at any frequency.

In a first step 210 can the engine control 30 or at least one module determine at what point (eg, crank angle) in the engine cycle the spark event is to take place. The engine control 30 may also calculate the optimal timing for the spark event based on engine operating conditions, such as intake charge temperature, fuel octane number, engine speed, and intake manifold pressure. The timing of the spark event may be adjusted while the engine is running, and it may be adjusted in real time, for example in response to changes in operating conditions. The first step 210 may include such a spark timing control setting. However, the spark timing can be adjusted by another controller or module, in which case in the first step 210 simply the spark timing is obtained from such another controller or module.

In a second step 220 For example, the amount of lift L of the intake valve at which the occurrence of a spark event is scheduled can be determined. Like the first step 210 , the second step 220 calculating the optimal intake valve control. However, the optimal valve timing may be calculated by another controller or module, in which case the second step 220 simply the valve control is obtained from such another controller. In the intake valve control, the second step 220 determine the amount of lift scheduled for the intake valve when the wasted spark event occurs.

In a third step 230 For example, the maximum tolerated intake valve lift L _{max may be determined} during the spark event. The maximum tolerated intake valve lift during the spark event may be a fixed value, e.g. Zero, or it may be a variable value, which may depend on when the spark event occurs.

For example, a larger amount of intake valve lift may be tolerated if the wasted spark event is scheduled to occur before the piston reaches top dead center (TDC) because the pressure and temperature of the gases in the combustion chamber may be lower , Conversely, if the wasted spark event is scheduled to occur after the piston reaches TDC, the maximum tolerated intake valve lift may be lower due to the higher pressure and higher temperature in the combustion chamber. In this regard, the third step may be 230 refer to a lookup table used in engine control 30 or stored on a separate memory module. The third step 230 may further comprise interpolating between data points from such a look-up table.

In a fourth step 240 is the amount of intake valve lift L, which is scheduled to occur in the Wasted Spark event, the second step 220 with the maximum tolerable intake valve lift L _max at the Wasted Spark event, the third step 230 was compared. If the amount of the intake valve lift L to be scheduled to enter the Wasted Spark event is greater than the maximum tolerated intake valve lift L _max in the Wasted Spark event, the process continues 200 at a fifth step 250 continued. However, if the amount of the intake valve lift L to be scheduled to occur in the Wasted Spark event is less than the maximum tolerated intake valve lift L _max in the Wasted Spark event, the process continues 200 at a sixth step 260 away, and the fifth step 250 is skipped.

In the fifth step 250 can the controller 30 delay the intake valve opening so that the intake valve lift in the Wasted Spark event is less than or equal to the maximum tolerated intake valve lift L _max that occurs in the third step 230 was determined. Alternatively or additionally, the fifth step 250 delay the injection of fuel, for example by the controller 30 sends a signal for adjusting the timing of the fuel injection. In any case, the amount of time delay required in the fifth step 250 be calculated. The likelihood of backfire into an intake manifold of the engine may be reduced because there is less air and / or fuel in the combustion chamber when a wasted spark event occurs.

In the sixth step 260 can the engine control 30 one of the ignition coils 10 . 20 and thereby cause a spark event in the respective cylinders. The procedure 200 may then be repeated, for example, for a subsequent spark event or in response to a change in spark timing.

Although the procedure 200 has been described above with reference to a number of steps, it will be understood that the steps may be performed in a different order. In addition, two or more of the steps may be performed simultaneously, for example, the second and third steps 220 . 230 be executed in parallel.

Referring to the 3 and 4 Now, a first example of the present disclosure will be described. In the in 3 The diagram shown corresponds to the vertical axis 310 the amount of intake valve lift while the horizontal axis 320 corresponds to the crank angle, where zero degrees correspond to top dead center (TDC) for a particular cylinder and piston. (VOT means "before top dead center", and NOT means "after top dead center".) The unadjusted scheduled intake valve lift profile will go through the line 340 characterized. The timing of the Wasted Spark event is through 330 characterized. At the second step 220 of the procedure 200 the intake valve lift will be at the scheduled spark event 330 certainly. In the fifth step 250 For example, the opening of the intake valve may be delayed to reduce the lift of the intake valve during the spark event. The delayed intake valve profile is indicated by the reference number 350 characterized. By delaying intake valve opening, the amount of intake valve lift from L to L was _once decreased, which may be equal to or less than L _max . The amount of air (and possibly fuel) in the cylinder of the wasted spark event has been reduced and, as a result, the likelihood that the wasted spark event will trigger combustion has also been reduced. Even though 3 shows the entire profile for delaying the intake valve opening, in an alternative arrangement, the opening of the intake valve may be delayed, while the closing of the intake valve may remain unchanged or be delayed by a different amount. In such circumstances, to compensate for the reduced intake of air, the intake valve may be opened a greater amount after the wasted spark event has occurred.

Now referring to 4 an example of how the maximum tolerated intake valve lift L _max varies in the Wasted Spark event with respect to timing is shown. The vertical axis 410 corresponds to the intake valve lift, and the horizontal axis 420 corresponds to the crank angle at which the Wasted Spark event is scheduled to occur. The relationship between the maximum tolerated intake valve lift L _max and the timing of the spark event is represented by the line 430 characterized. As shown, the maximum tolerated intake valve lift may decrease if the wasted spark event is scheduled to occur later in the engine cycle. The reduction in the maximum tolerated intake valve lift may flatten for wasted spark events scheduled to occur after top dead center. The maximum tolerated intake valve lift may level out at an intake valve lift value of about 1 mm. It has been found that the probability of flame propagation through a gap of 1 mm or less is small. Therefore, an intake valve lift value of 1 mm or less can be tolerated when a wasted spark event occurs at or after TDC. Conversely, if the wasted spark event is scheduled to occur before TDC, a larger intake valve lift value may be tolerated as the pressures and temperatures in the combustion chamber may be lower and the likelihood that a wasted spark event will initiate combustion is low.

In the 4 The relationship shown is merely one example of the functional relationship between the maximum tolerated intake valve lift L _max and the Wasted Spark event timing. It is understood that this functional relationship may take other forms, for example, the maximum tolerated intake valve lift L _{max may be} a constant value, such as 1 mm or even zero mm. The shape of the relationship between the maximum tolerated intake valve lift and the time of the wasted spark event may be determined experimentally or by calculation. The relationship between the maximum tolerated intake valve lift and the wasted spark event timing may be in a memory module associated with the engine control 30 is linked, for example in the form of a look-up table containing a number of discrete points from the line 430 includes, between which can be interpolated.

Now referring to 5 A second example of the present disclosure will be described. This in 5 Diagram shown is similar to the one in 3 shown, insofar the vertical axis 510 represents the amount of intake valve lift, the horizontal axis 520 represents the crank angle and the line 530 indicates the timing of the Wasted Spark event. In addition, the planned lift amount for the intake valve becomes a function of the crank angle through the reference number 540 characterized. As described above, in the fifth step 250 the timing of the fuel injection to be delayed. In this regard 5 the unadjusted timing of the fuel injection 550 wherein the injection start (SB) by 552 is characterized and the injection end (SE) by 554 is marked. In one particular example, the fuel may be injected into a suction passage upstream of the intake valve, but it may also be considered that the fuel is injected directly into the cylinder. As a result, in the particular example in which the fuel is injected into the suction passage, the fuel may reach the cylinder with a delay, since the fuel can flow into the cylinder only when the intake valve is opened. The fuel transport delay in the case that the timing of the fuel injection is unadjusted is determined by 556 and, as shown, the fuel may have entered the cylinder shortly after the intake valve has opened.

In the event that the fourth step 240 determines that the planned intake valve lift in Wasted Spark event is greater than the maximum tolerated intake valve lift, the injection of the fuel can be delayed. The timing of the delayed fuel injection is through 560 designated, wherein the beginning of the set injection by 562 is called and the end of the set injection through 564 referred to as. Since the fuel injector may be upstream of the intake valve, there may be a transport delay until the fuel enters the cylinder, and this delay is indicated by the reference number 566 denotes, in the event that the fuel injection by a fifth method step 250 is delayed. The fuel transport delay 566 can from the beginning of the set injection 562 apply since the beginning of the set injection 562 may occur after the inlet valve has opened. As a result, the injected fuel can be taken directly from the flowing intake air and does not have to wait for the opening of the intake valve. Accordingly, the fuel transportation delay begins 566 in the illustration at the beginning of the set injection 562 ,

As illustrated, the fuel injection may be adjusted so that the fuel arrives in the cylinder after the wasted spark event has occurred. Taking into account the transport delay 566 can be the beginning of the set injection 562 therefore occur before the Wasted Spark event occurs. When the fuel arrives in the cylinder after the wasted spark event has occurred, the likelihood of the wasted spark event triggering combustion has been reduced. Although the fuel in the presentation of 5 After the Wasted Spark event has occurred, it is also contemplated that the adjusted fuel injection may allow some fuel to arrive before the wasted spark event occurs, for example, assuming that the concentration of the fuel in the Cylinder is sufficiently low at the onset of the Wasted Spark event that the likelihood that the Wasted Spark event will result in igniting the combustion is low.

It is understood that the functional relationship between the maximum tolerated intake valve lift and the time of the wasted spark event, such In 4 can be equally applied to the second example of the present disclosure. In other words, fuel injection may be retarded if the scheduled intake valve lift exceeds the maximum tolerated intake valve lift on the wasted spark event.

The method and systems described herein may be applied to an engine that includes valve actuators that may vary the timing and / or extent of valve opening. For example, the intake valve lift may be adjusted with a variable lift control device or via a variable camshaft control with a fixed lift profile.

It should be understood that one or more controllers include other modules configured to carry out any of the above-mentioned methods. For example, the controllers may determine in which operating mode the internal combustion engine is operating. It will also be understood that the controls may include existing controls that have been reprogrammed to perform any of the above-mentioned methods. Moreover, the method and system described herein do not require additional hardware and can therefore be implemented at low additional cost. If necessary, they can also be retrofitted to existing vehicles.

It has been determined that the probability of a kickback event occurring may be greatest when the wasted spark event occurs after TDC (eg, due to a combination of high compression ratio and high inlet temperature) and / or when Inlet valve lift is greater than 1 mm (because, for example, such a gap could allow flame propagation through the valve). The present disclosure beneficially recognizes these factors and reduces the likelihood of the kickback event occurring.

It will be understood by one skilled in the art that although the invention has been described by way of example with reference to one or more examples, it is not limited to the examples disclosed and alternative examples could be formed without departing from the scope of the invention as defined by the appended claims ,

Claims (20)

A method for a spark-ignition internal combustion engine, the method comprising: energizing a common ignition coil for simultaneously actuating a first spark event on a first spark plug coupled to a first cylinder of the engine and a second spark event on a second spark plug coupled to a second spark plug Cylinder of the engine is coupled, wherein the engine is designed so that at a certain ignition coil excitation, the spark event in only the first or second cylinder is used to initiate a combustion, while the spark event in the others are wasted from the first and second cylinders; and selectively retarding intake valve opening and / or fuel injection for the other from the first and second cylinders to prevent backfire into an intake manifold of the engine. The method of claim 1, further comprising: Adjusting a timing of the ignition coil excitation based on the operating conditions of the engine. The method of claim 1 or 2, further comprising: Determining the scheduled intake valve lift for the other of the first and second cylinders during the spark event. The method of claim 3, further comprising: Delaying intake valve opening and / or fuel injection for the other of the first and second cylinders when the scheduled intake valve lift for the other of the first and second cylinders is greater than or equal to a maximum tolerated intake valve lift for the other of the first and second cylinders Spark event is. The method of claim 4, further comprising: Determining the maximum tolerated intake valve lift for the other of the first and second cylinders during the spark event. The method of claim 4 or 5, further comprising: Delaying the intake valve opening such that the intake valve lift for the other of the first and second cylinders in the spark event is equal to or less than the maximum tolerated intake valve lift for the other of the first and second cylinders in the spark event. The method of any one of claims 4 to 6, further comprising: Delaying fuel injection so that not all of the fuel to be injected is in the other of the first and second cylinders when the spark event occurs. The method of any one of the preceding claims, further comprising: Determining a likelihood of a check in the intake manifold of the engine based on the timing of the ignition coil energization and the intake valve control. The method of any one of the preceding claims, further comprising: Determining if the intake valve opening and / or fuel injection for the other of the first and second cylinders is to be delayed. The method of any one of the preceding claims, further comprising: Adjusting the length of the delay of the intake valve opening and / or the fuel injection as a function of the timing of the ignition coil excitation. The method of claim 9 or 10, further comprising: Performing the determination of whether to open the intake valve opening and / or retard the fuel injection for the other of the first and second cylinders while the engine is operating. A method according to any one of the preceding claims, wherein, for the particular ignition coil excitation, a first piston in the first cylinder is in a compression stroke and a second piston in the second cylinder is in a power stroke. The method of any preceding claim, wherein for a subsequent ignition coil excitation, it is intended that the spark event in the other of the first and second cylinders cause combustion and that the spark event is wasted in the first or second spark event; the method further comprising: selectively delaying intake valve opening and / or fuel injection to the first or second cylinders to prevent backfire into the intake manifold of the engine. The method of any one of the preceding claims, further comprising: Energizing a further common ignition coil for simultaneously actuating a third spark event on a third spark plug coupled to a third cylinder of the engine and a fourth spark event on a fourth spark plug coupled to a fourth cylinder of the engine, the engine thus configured is that at a certain excitation of the further ignition coil, the spark event in only one of the third and fourth cylinders is used to initiate combustion, while the spark event in the other of the third and fourth cylinders is wasted; and selectively delaying intake valve opening and / or fuel injection for the other of the third and fourth cylinders to prevent backfire into the intake manifold of the engine. An engine ignition system for a spark-ignition internal combustion engine, the engine comprising: a first spark plug for triggering a first spark event in a first cylinder of the engine; a second spark plug for triggering a second spark event in a second cylinder of the engine; and a common ignition coil coupled to both the first and second spark plugs; wherein the engine ignition system includes one or more engine controls configured to activate the ignition coil to simultaneously energize both the first and second spark plugs so that the first and second spark events occur simultaneously; such that in a given ignition coil excitation, the spark event in only the first or second cylinder is intended to initiate combustion, the spark event in the other being wasted from the first and second cylinders; and wherein the engine controls are further configured to selectively open an intake valve and / or retard fuel injection for the other of the first and second cylinders to prevent backfire into an intake manifold of the engine. The engine ignition system of claim 15, wherein the one or more engine controls are further configured to perform the method of any one of claims 2 to 13. Software that, when executed on a computing device, causes the computing device to perform the method of any one of claims 1 to 14. A vehicle or engine comprising the engine ignition system for a spark-ignition internal combustion engine according to claim 15 or 16. Method for a spark-ignition internal combustion engine, substantially as described herein with reference to and as shown in FIGS 2 to 5 described. An engine ignition system for a spark-ignition internal combustion engine, substantially as described herein with reference to and as shown in FIGS 1 and 3 to 5 described.

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