Thanks for all of the answers!   So now, the point of my question (and this
is really the end), was that I was curious if this fuel shutoff still works
once the o2 sensor has cooled down.  I'd be driving down a really long hill
with the van in gear, and at the top, I'd be happy about the fact that I was
consuming zero fuel, and then, once I had gone far enough the o2 sensor was
cool and reading flat, I was wondering whether I was still consuming no
fuel, or whether I was now consuming fuel after all.  If the engine braking
fuel shutoff still works after the o2 sensor cools, it means it's still most
fuel efficient to stay in gear.  I guess if it doesn't, you should be better
idling on the way down, or shutting off the engine.

On Sat, Aug 30, 2008 at 2:50 AM, Dennis Haynes <d23haynes57@hotmail.com>wrote:

> No, fuel cut off only occurs when the engine is warmed up enough for
> closed loop operation.
>
> Dennis
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> pickle vanagon
> Sent: Saturday, August 30, 2008 1:19 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: When the O2 sensor cools down...
>
> On Fri, Aug 29, 2008 at 10:25 PM, Dennis Haynes
> <d23haynes57@hotmail.com>wrote:
>
> > Engine braking is strictly a function of the closed throttle causing
> high
> > manifold vacuum as the engine is being driven by the wheels. Yes, engine
> > braking is caused by vacuum, not compression.
> >
>
> What I meant to ask, is whether the ECU still shuts off fuel to the
> injectors above the cutoff (I thought it was 2000rpms?) at zero throttle
> even if it is not yet in closed loop mode.  It makes sense that it would,
> I
> just can't verify this with the mixture meter since the o2 sensor is
> nonfunctional at this point.
>