this post was submitted on 08 Sep 2023
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The most difficult part lf stanrting a car is gettinf the pistons to move, if your engine still has inertia (if you are going downhill for example) you can completely cut the fuel injection and it can starts again because the pistons that are still moving will compress the gas (and for diesel engine that's enough to ignite given enough temperature in the block, for gasoline the spark plugs will work as usual).
Of course if the engine has low inertia (it's spinning too slowly) the car will stall, but probably the electronic injection will compensate.
If you drive manual you can go down a hill without burning a single drop of fuel, not sure if automatic are smart enough to do it.
In my car with automatic CVT transmission, I have to downshift using the paddle shifter in order to force it to do engine braking. It doesn't do any engine braking if I simply let the gas pedal go.
It is probably still "engine braking" in that the engine is putting resistance on the wheels, but it's probably opening the throttle and halting fuel injection in order to maximize your coasting/minimize rolling resistance.
CVTs usually use a clutch rather than a torque converter, so they like to stay "locked up" to minimize wear.
I think. Not a mechanic, and I drive a manual.
In my car (it has a cvt transmission with a torque converter instead of a clutch), it doesn't seem to do any engine braking though. In a steep downward incline, if I let go of the gas pedal, the car would just keep getting faster and faster without any resistance at all. Force a downshift and acceleration will stop, and the fuel efficiency indicator shot up which indicate it doesn't use fuel at all (thus doing an engine braking).