[Vwdiesel] Why gasss cars mpg sucks

[Val Christian]

> > A couple of things...first, the TDI DOES shut off all injection
> > in a coast operation.  I've observed that, and verified it as
> > correct behavior for the TDI.
> > 
> > 
> 
>   So when you top over a hill, (and keep going of course)  the TDI 
> engine actually shuts off?  Seems like something DOT wouldn't 
> approve of regardless of ramifications or not.  Seems like a 
> freewheeling (ala E-mode) would save even more fuel.  If that's 
> the intent.
>     Loren

When you top a hill, and start down, coasting, the injection level 
commanded by the ECU can drop to zero.  It's a function of power commanded.
Taking your foot off the pedal, it will drop to zero.  Depending upon
the hill, not moving your foot may cause some fuel to be commanded
to be injected.  But simply stated, yes, fuel can (and often does)
drop to zero.  It's not freewheeling, per say, because the entire 
engine (altenator, compressor, power steering, pistons and valvetrain)
keep turning.  So when the available power exceeds those, you get a 
free ride.

Val