HONDA Insight - Manual (Page 52)

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Energy flow from wheels to crankshaft (no fuel burned)
Whenever the Insight is moving with the clutch engaged and the transmission in gear, the gasoline
engine is mechanically connected to the wheels, and so it must continue to turn also. However, this doesn't
necessarily mean that it is consuming any fuel.
During deceleration, if the clutch is engaged and the transmission is in gear, the IMA will typically
enter fuel cut mode. This is considered a separate mode from idle stop mode, as the engine (and by
extension any engine-driven accessories such as the air conditioning compressor) is continuing to be turned
by the wheels. In idle stop mode, the engine is not turning at all.
Fuel cut mode will take place at engine speeds above 1100 rpm. If the engine speed falls below 1100
rpm, fuel will be supplied to prevent the engine from stalling when the driver releases the clutch.
So, this is what takes place during a typical deceleration:
• When the driver releases the accelerator pedal, a low level of regenerative braking takes place,
and the gasoline engine enters fuel cut mode.
• When the brake pedal is applied, a higher level of regenerative braking takes place. The
engine is still in fuel cut mode, rotating but not burning any fuel.
• When the driver presses the clutch pedal, the car may now enter idle stop mode where the
engine no longer turns at all. In this case, no fuel will be consumed from the time the driver
began decelerating until the driver reaccelerates. If the conditions for idle stop are not satisfied
when the driver releases the clutch pedal (for instance, battery level is too low), fuel cut mode
will end, and fuel will be delivered to the engine to keep it running.