Date:         Mon, 21 Nov 94 16:11:59 EST
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         dcarment@ccs.carleton.ca (David Carment)
Subject:      Re: Oxygen Sensor / Full Throttle Switch

Dave Kautz writes:
> 
> > > 
> > OK but can you tell us how to test it? The Hayne's is unclear and even
> > though i have replaced the "black box" it still seems to make little
> > noticeable difference. Your idea of peak temps is interesting though.
> > Earlier I had asked if removing the EGR would be detrimental, after all it
> > also reduces peak temps by inserting inert gas into the combustion chamber
> > no consensus on that one either ------DC
> > -- 
> > 
> > ----------------------------------------------------------------------
> > David Carment
> > 
> 
> 
>     I'll look it up when I go home for lunch. 
> 
>     I am interested by your discussion of the effect of EGR. I believe your
>     description of it's function is indeed correct, it is not for "recycling"
>     exhaust as many believe. The reduction of peak temps is to attenuate the
>     production of oxides of Nitrogen (pollutants) that are formed only at high
>     temperatures.
>     Two bits of anecdotal stuff. I once disconnected the EGR on a Datsun 210
>     that the wife had and the only observable result was that the engine temp
>     gauge indicated higher temps in normal driving. The Magliozzi brothers have
>     directed several callers to check their EGR in response to complaints about
>     "pinging" - one source of which can be high combustion chamber temperatures.
> 
>         I think this is further complicated in that combustion
>     temperature and the amount of combustion may be somewhat seperate. What I'm
>     thinking of here is that at part throttle the total amount of air and fuel
>     is less in any single cycle of combustion than at full throttle but the 
>     temperature at which the combustion takes place may be independant of that
>     and determined by things like spark lead, EGR, fuel/air mixture, chemical
>     composition of the gasoline etc. I'm just speculating here and would
>     appreciate elucidation....
> 
> 
>     Dave Kautz
> 
This is interesting, because the EGR for the Vanagon is designed to work
at idle and full throttle but not in between. When we were experiencing
stumbling at start up, the mechanic put a washer in the EGR valve which
effectively reduced the amount of gas, interestingly it did ok on
emmissions both ways.... I have tried plugging the EGR but have had the same
concern, higher head temps (this may be more important for a Vanagon engine
that is operating at 350F). Joel says its ok, but since he doesn't have a
PhD in physics I am not sure I can trust him....;). DC

-- 

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David Carment
School of International Affairs
Carleton University
Ottawa, Ontario
K1S 5B6
voice - (613) 788-2600-6662
fax - (613) 788-2889
Email address: dcarment@ccs.carleton.ca
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