View Single Post
Old 12-25-2008, 11:15 PM   #5 (permalink)
Old Retired R&D Dude
Join Date: May 2008
Location: Woburn Mass USA
Posts: 701

Little Red - '12 Toyota Prius c 2 Two
90 day: 57.82 mpg (US)

"Whitey" Bulger - '14 Toyota RAV4 LE
Thanks: 10
Thanked 18 Times in 17 Posts
Originally Posted by NeilBlanchard View Post

There was a thread on this very same topic, fairly recently.
Yeah, I did read one the other day about using a non-OEM CC to get better FE.

The poster was using a Ford MAP? that would vary an output frequency
as the vacuum pressure(MPG) changed..

I was thinking maybe something like a Frequency Switch
Frequency Switch: 14447 AutoSpeed
could be used with that Ford part, to detect when MPG was poor
and back off on the CC by putting a few pluses on the Set/DECEL I/O line..

All we would need is someone to program a little controller chip to
apply up and down pulses to the CC.. (1 MPH increments).

Should not be hard to make a device that would send a Down(decel) pulse
once ever 2 or 5 seconds while the MPG is bad..
Once you hit the top of the hill,(And MPG was good) the device could send Up pulses to get the car back to speed..
The firmware would have to keep track of the pulse count, in the event
of a very short hill. (interrupted the down sequence)
Making the applied pulse frequency variable, you could set it for long slow
hills or short steep ones.

The idea would be to knock back the speed on hills to keep the MPG from
taking a nose dive and then speed back up at the top, automatically..
Have a dip switch, so you could select how many MPH you wanted slow down.. 4 or 5 MPH drop should be safe if there are no tailgators..

Heck, while we're dreaming, let's add an I/O line that can be used to
switch off the AC solenoid when the MPG goes sour..

Current ride: 2014 RAV4 LE AWD (24 MPG)

Wife's Pizza Transporter
  Reply With Quote