View Single Post
Old 02-07-2011, 12:23 AM   #29 (permalink)
abell75
EcoModding Lurker
 
Join Date: Nov 2010
Location: St. Louis
Posts: 38

Grand Prix - '02 Pontiac Grand Prix GP
90 day: 24.01 mpg (US)
Thanks: 3
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by roosterk0031 View Post
... Only time I could get the scangage to go 9999 so fuel is cut off is ...
Quote:
Originally Posted by Thymeclock View Post
I'm not sure of how you would know even with a scangauge. Would anyone know?

From the Scangage II manual:
Quote:
Some vehicles will turn the fuel injectors off when coasting. This will
cause the fuel economy to go to 9999 MPG or 0.00 KHL. This shows
when you are not using any fuel while coasting.
Quote:
Originally Posted by Thymeclock View Post
Assuming you have an automatic transmission: my rule of thumb is to coast in neutral when approaching a stop sign. You need to stop anyway, and the car will roll further when not in gear. If I'm approaching traffic light however, I stay in gear because it allows me to maintain speed or accelerate if needed. It is questionable whether some transmissions can be shifted from neutral in to drive at higher speeds without incurring damage to the transmission.
My thinking is that if I'm going to stop anyway, then not using fuel when coasting to the stop is better than coasting in neutral because in neutral you need to use fuel to keep the engine running (assuming you don't shut off the engine - most of my coasts are too short for this). I won't coast as far, but that just means I use the brakes less.

So if fuel goes to zero, I'll leave it in gear. If the injectors keep supplying fuel anyway, then I'll put it in neutral so I can let off the throttle sooner.
  Reply With Quote