Maximizing MPG on Long Uphill Grades

<div class='quotetop'>QUOTE(hobbit @ Aug 3 2006, 03:45 PM) [snapback]297194[/snapback]</div>

Explain that one!

 

Easy. http://techno-fandom.org/~hobbit/cars/squirt/ illustrates
a simple injection meter, that DOES NOT lie about consumption. Some
people have observed that things like the ScanGauge register a
trickle in fuel-cut states, so in this case bypassing the computers
is useful. I've also scoped the same outputs so I know exactly how
long the injector pulses are during a lot of these conditions.
.
In neutral, regardless of vehicle speed, the hybrid controller totally
lets go of any motor control, including relinquishing the ability to
start or stop the engine. So if it's already running [turning] it
stays running, or if it's already shut down it stays that way. But
without any help from the electric motors, now the engine ECU has
to go to an idling state at about 950-1000 rpm to remain running.
Minimum injector pulse is right around 2 ms, visible at the blinkie
LED and on the scope.
.
This is why "warp neutral" works, too -- if you start below 42 mph
and remove the ability for the hybrid system to effect engine control
by being in neutral, you can reach much higher speeds without spinning
the engine. At 68 mph you reach the theoretical 10,000 RPM limit
of MG1. Somewhere along the scale you're probably getting more
viscous drag from the motors thrashing the transaxle fluid, so it's
probably better to use warp-stealth for extended high-speed coasting
instead. Besides, I expect Ken will pop in here and say "bad idea
to coast in neutral" as usual, although I've never seen his reasoning.
.
Now, this original thread was about *uphill*, not *downhill*.
Recent research indicates that staying under 2300 RPM and allowing
speed to bleed off as needed is part of the right answer here. You
might find yourself crawling up amidst the big semis, but your
MPG will definitely be higher. Why? Between 2200 and 2400 rpm,
near as I can determine, the valve timing is changed in a way that
eats just a little more gas for motive power gained.
.
But really, it's not just about uphill technique ... it's what you
do overall that contributes to the *average*. Warp-stealth is
probably your strongest ally.
.
_H*