Engine Brake and Acceleration Hesitation
#16
Lead Lap
"...A non-synchronous injection in which injection was influenced by signals from sensors (regardless of the crankshaft angle). To protect the engine and improve fuel economy, the system could temporarily cut off fuel supply..."
http://australiancar.reviews/2GR-FE-engine.php
http://australiancar.reviews/2GR-FE-engine.php
#19
Lexus Champion
Nate, this is pretty interesting info! Very nice find!
However, some things I would question, in particular the duration of the fuel cut-off. Is it a fraction of a second?
It's pretty cool that they stop the fuel supply while the RPMs are dropped suddenly.
This is probably something similar to the cut-off that happens on an over-rev situation or traction control engagement.
But what happens when the vehicle is moving and the throttle is released?
First thing I noticed in the 16 RX350 loaner, compared to the RX450h is the lack of engine-[regen]-braking.
It is more efficient to let the engine idle at low RPMs and disengage the transmission than keeping the engine rotating at the proper speed.
That would be easy-enough to check by someone with a real automatic by releasing the throttle while cruising at a highway speed. If RPMs drop but there is no corresponding deceleration, then the engine is just idling, uncoupled from the driving wheels.
There is no way the fuel is cut of any long period of time. In the least, it would be advertised as a "feature". Also, the end-users would be very much aware of this. Restarting engine in gear is not a completely transparent process. A Toyota hybrid is about as smooth as it gets and it's not completely unnoticeable.
However, some things I would question, in particular the duration of the fuel cut-off. Is it a fraction of a second?
It's pretty cool that they stop the fuel supply while the RPMs are dropped suddenly.
This is probably something similar to the cut-off that happens on an over-rev situation or traction control engagement.
But what happens when the vehicle is moving and the throttle is released?
First thing I noticed in the 16 RX350 loaner, compared to the RX450h is the lack of engine-[regen]-braking.
It is more efficient to let the engine idle at low RPMs and disengage the transmission than keeping the engine rotating at the proper speed.
That would be easy-enough to check by someone with a real automatic by releasing the throttle while cruising at a highway speed. If RPMs drop but there is no corresponding deceleration, then the engine is just idling, uncoupled from the driving wheels.
There is no way the fuel is cut of any long period of time. In the least, it would be advertised as a "feature". Also, the end-users would be very much aware of this. Restarting engine in gear is not a completely transparent process. A Toyota hybrid is about as smooth as it gets and it's not completely unnoticeable.
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