The decision for the ecu to go closed loop is based on temperature, not
whether or not the O2 sensor is creating a usable signal. On a warm
engine, the ecu will still do the fuel cut off even if the O2 sensor is
missing. This is actually a good thing as you don�t want the engine to get
too cold.

Dennis

-----Original Message-----
From: pickle vanagon [mailto:greenvanagon@gmail.com]
Sent: Saturday, August 30, 2008 12:24 PM
To: Dennis Haynes
Cc: vanagon@gerry.vanagon.com
Subject: Re: When the O2 sensor cools down...

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.