Quote:
Originally Posted by KY_Canyon
For hypermiling purposes engine braking is still inefficient when compared to coasting in neutral......could be better or worse than using normal brakes, but it's still a loss of kinetic energy. In a manual transmission, you can simply avoid it with use of the clutch, but for those of us with automatics it can make a huge difference. Engine braking is a safety feature, not an efficiency feature.
My 2005 Canyon Auto uses DFCO under certain conditions, and while more efficient than traditional injector on engine braking it is still much less efficient than neutral coasting. In it the DFCO is programed to kick off somewhere below 1800 RPM and the truck begins to coast (free wheel). So for me, coasting down hills at speeds above 60 or so causes the DFCO to kick on (which drives me crazy). If I'm at 58 MPH then the coasting is almost like driving a manual, but I never have to press a clutch. I'm hoping that the DFCO parameters can be adjusted with a custom PCM reprogramming. I think my MPG would improve significantly if the engine DFCO only operated above 2100 RPM or so.
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My corolla is almost the exact opposite to your canyon, it does DFCO if I let off the gas enough at almost any speed including NEUTRAL (very short time of course)! I think it uses the TPS and engine load/MAP to determine when it go into DFCO mode. Going 45mph, I can coast about a mile and still be moving ~25mph before my engine kicks in and my scan gauge says around 80mpg. If I stick it in neutral at that point, my mpg drops... I don't know why. Coasting in neutral for me gives maybe 15-20% further coast, but uses fuel, about 140mpg down to the 70s when it gets down to 25mph. For my case, I think DFCO is the better pick for me.