A system for determining properties of fuel supplied to an internal combustion (IC) engine and for adjusting operations of the IC engine based on the determined properties. The system includes an air-flow throttle configured to control the air supplied to the IC engine; a fuel-flow throttle configured to control the fuel supplied to the IC engine; and an engine control module (ECM) configured to receive readings from and control operation of the throttles. The ECM is configured to perform a fuel-air determination program where the ECM determines a percent-error air-to-fuel ratio (AF) based on a true AF ratio compared to an ideal AF ratio. The ECM is configured to perform a fuel property determination and adjustment program in which the ECM is configured to adjust operations of the IC engine based on a fuel property value determined using the percent-error AF ratio.

Methods and systems are provided for adjusting a throttle during deceleration fuel shut off (DFSO). In one example, a method may comprise controlling a position of a throttle in an air inlet of an engine propelling a vehicle, in relation to vehicle operator commands, and during a deceleration fuel shut off mode, increasing opening of said throttle independently of said operator commands when speed of said vehicle is or is expected to fall below a desired speed or desired speed trajectory.

Methods and systems for operating an engine that includes an electrically operated throttle are disclosed. In one example, mitigating actions are taken in response to degradation of the electrically operated throttle so that the engine may be operated in a way that allows a driver to reach a service area.

A vehicle comprises an engine, a throttle body including a passage section and a throttle valve, and a throttle valve controller which controls opening or closing of the throttle valve, wherein the throttle valve controller includes: a memory section which contains therein a medium output control command such that the medium output control command continues to be stored in the memory section in a state in which electric power supply to the throttle valve controller is ceased, the medium output control command indicating an opening degree of the throttle valve, corresponding to a preset medium output range, and wherein the throttle valve controller controls opening or closing of the throttle valve, in accordance with the medium output control command read from the memory section, when an engine output meets a medium output condition in which the engine output is controlled to fall into the medium output range.

Methods and systems are provided for adjusting a throttle during deceleration fuel shut off (DFSO). In one example, a method may comprise controlling a position of a throttle in an air inlet of an engine propelling a vehicle, in relation to vehicle operator commands, and during a deceleration fuel shut off mode, increasing opening of said throttle independently of said operator commands when speed of said vehicle is or is expected to fall below a desired speed or desired speed trajectory.

A system for determining properties of fuel supplied to an internal combustion (IC) engine and for adjusting operations of the IC engine based on the determined properties. The system includes an air-flow throttle configured to control the air supplied to the IC engine; a fuel-flow throttle configured to control the fuel supplied to the IC engine; and an engine control module (ECM) configured to receive readings from and control operation of the throttles. The ECM is configured to perform a fuel-air determination program where the ECM determines a percent-error air-to-fuel ratio (AF) based on a true AF ratio compared to an ideal AF ratio. The ECM is configured to perform a fuel property determination and adjustment program in which the ECM is configured to adjust operations of the IC engine based on a fuel property value determined using the percent-error AF ratio.

A system for determining properties of fuel supplied to an internal combustion (IC) engine and for adjusting operations of the IC engine based on the determined properties. The system includes an air-flow throttle configured to control the air supplied to the IC engine; a fuel-flow throttle configured to control the fuel supplied to the IC engine; and an engine control module (ECM) configured to receive readings from and control operation of the throttles. The ECM is configured to perform a fuel-air determination program where the ECM determines a percent-error air-to-fuel ratio (AF) based on a true AF ratio compared to an ideal AF ratio. The ECM is configured to perform a fuel property determination and adjustment program in which the ECM is configured to adjust operations of the IC engine based on a fuel property value determined using the percent-error AF ratio.