which trigger or whose output is analyzed by the ecu to trigger the firing order switch for example it may include a gear sensor which detects which gear the gearbox not shown is in an rpm sensor which detects how fast the crankshaft is rotating a wheel speed sensor which determines the road speed of the vehicle a throttle position sensor which determines the position and or velocity of the throttle a global positioning position gps receiver and or an inertial position sensor such as a computerized track map coupled with an accelerometer the environmental sensors are coupled to the ecu or to a secondary control module not shown which analyzes their output fig1 illustrates the 360 u00b0 phase shift that happens when a cylinder 39 s firing sequence is changed pursuant to a switch from an old firing order to a new firing order the firing order selector can be triggered e g by the rider at any arbitrary point during the 720 u00b0 four stroke cycle in one embodiment the current stroke is allowed to run normally to completion and the change is made at the end of that stroke by simply switching to the next stroke of the new firing order if the rider triggers the switch at any time during the intake stroke the intake stroke runs to completion meaning the intake valve i v is opened the spark plug is optionally fired the fuel injector f i is opened and allowed to inject fuel for a time then the fuel injector is closed and the intake valve is closed then at the 180 u00b0 rotation mark instead of continuing on with.