View Single Post
Old 09-30-2010, 01:58 PM   #19 (permalink)
greasemonkee
EcoModding Apprentice
 
Join Date: May 2009
Location: Western NC
Posts: 177
Thanks: 3
Thanked 43 Times in 19 Posts
It really depends on throttle body sizing vs. engine displacement as to what throttle position is most efficient at X rpm. Here I'm aiming to regulate manifold pressure to achieve it's peak efficiency. But you're right, very light loading is quite inefficient and better to shut the engine off and coast. There is a fine line in loading engines with a factory tune running closed loop - once you cross the threshold by loading too much by either falling out of lean burn or, at the least, falling out of stoichiometry. I don't like to use throttle position as a term for referencing loading, since (at least hondas) closed loop threshold is determined by the ecu via the table values - throttle position vs. rpm - and using the algorithms to generate the final value. In the end, the table more closely mimics manifold pressure. Generally, the cars I tune gently taper down to rich after 750 millibars, so my intuition tells me somewhere in that area is the target for lowest bscf.

It did take a bit of shifting my driving style around to figure what it liked. I do know that she doesn't like to be loaded much (manifold press) at low rpm (1000-2000). Theory meets reality.

I don't care for pulse and glide unless it's down hill of a .5 mile minimum and can retain the posted speed limit
  Reply With Quote