Method for reducing misfire in an internal combustion engine
View Patent ↗The present invention is a method for reducing misfire in a cylinder of an internal combustion engine. The method includes detecting a misfire event frequency that is equal to or greater than a first predetermined value, determining a pulse-width signal for a fuel injector associated with the cylinder during the misfire event, increasing the pulse-width signal if the misfire event is frequency is below a second predetermined value, and reducing the increase in the pulse-width signal if the misfire event frequency is below the first predetermined value.
1. A method for reducing engine misfire events in an internal combustion engine having at least one cylinder, a fuel injector associated with each cylinder and an electronic control unit providing control signals to open and close each fuel injector, said method comprising:
i) determining whether a frequency of misfire events detected in a given cylinder of said engine during a given time period is equal to or greater than a first predetermined calibration value;
ii) determining a pulse-width of the control signal for the fuel injector associated with the cylinder during the given time period;
iii) determining whether the determined pulse-width corresponds to an engine operating state where the fuel injector may be delivering an improper amount of fuel;
iv) increasing via the electronic control unit the pulse-width of the control signal for the fuel injector if the frequency of misfire events detected during the given time period is within a range defined by the first predetermined calibration value and a second, higher, predetermined calibration value; and
v) reducing the increase in pulse-width if the frequency of misfire events detected in a subsequent time period is less than the first predetermined calibration value.
2. The method of claim 1 wherein the electronic control unit further comprises a misfire event timer for detecting the frequency of misfire events.
3. A method for reducing engine misfire events in an internal combustion engine having at least one cylinder, a fuel injector associated with each cylinder and an electronic control unit providing control signals to open and close each fuel injector, said method comprising:
i) determining whether a frequency of misfire events detected in a given cylinder of said engine during a given time period is equal to or greater than a first value determined during engine calibration or testing;
ii) determining a pulse-width of the control signal for the fuel injector associated with the cylinder during the given time period;
iii) determining whether the determined pulse-width corresponds to an engine operating state where the fuel injector may be delivering an improper amount of fuel;
iv) increasing via the electronic control unit the pulse-width of the control signal for the fuel injector if the frequency of misfire events detected during the given time period is within a range defined by the first value and a second, higher, value determined during engine calibration or testing; and
v) reducing, the increase in pulse-width if the frequency of misfire events detected in a subsequent time period is less than the first value or greater than the second value.
4. The method of claim 3 further comprising maintaining the increase in pulse-width if the frequency of misfire events detected is between the first value and the second value.
5. The method of claim 1 further comprising detecting a coolant temperature of the engine and increasing the pulse-width if the coolant temperature is in a stable operating range.
6. The method of claim 1 comprising detecting a fault code for the fuel injector and wherein pulse-width is not increased if the fault code has been detected.
7. The method of claim 1 wherein the engine comprises more than one cylinder, and detecting the frequency of misfire events includes identifying a misfiring cylinder.
8. The method of claim 1 wherein the engine operating state where the fuel injector may be delivering an improper amount of fuel corresponds to engine idle.
9. The method of claim 1 wherein the engine operating state where the fuel injector may be delivering an improper amount of fuel corresponds to engine operation at part-throttle and low load.
10. The method of claim 1 wherein the pulse-width is increased in incremental steps.
11. The method of claim 10 wherein the pulse-width is reduced in incremental steps and reducing steps are smaller than increasing steps.
12. The method of claim 1 , wherein if multiple misfire events are detected during the given time period, the pulse-width of the control signal for the fuel injector is increased each time a misfire event is detected.
13. The method of claim 3 , wherein if multiple misfire events are detected during the given time period, the pulse-width of the control signal for the fuel injector is increased each time a misfire event is detected.