Date:         Mon, 21 Nov 94 11:27:15 PST
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         Dave Kautz <dkautz@hpsidms1.sid.hp.com>
Subject:      Re: Oxygen Sensor / Full Throttle Switch

> > 
> 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