AFM measurement/backpressure (was Turbo speed sensor)

[Mike (Perth, Western Australia)]

At 10:59 AM 9/3/2000 -0800, Ludis Langens <ludis at cruzers.com> wrote:
>Bernd Felsche wrote:
>> 
>> Yes; retard with EGR because the mixture is more volatile. There is
>> more energy in the mixture before compression increasing the
>> likelihood of knock.
>
>GM advances the timing when they turn on EGR.  This causes pinging when
>the EGR valve fails (closed) but the ECM doesn't notice.

Sounds like a classic nonlinear relationship, EFI is frought with them,
or rather I should say combinatorial chemistry/hydrostatics is frought ;-)

A little EGR and you need to retard a little more over some threshold
and oyu need to advance again. I remember something in SAE about this
but it was almost 20 years ago and my memory is dynamic ;)

I guess if the EGR is cool then advance would be the order of the day,
ie such as in those classic bypass arrangements into carby,
if however EGR is hot (via normal chamber ops) then retard would be
more likely - hot exhaust will take up much more room and will definitely
increase propensity for pinging, soucre of heat can't be ignored.

Complex if oyu have cool EGR and high valve overlap, would make the ECU
workovertime to handle the correct timing when the valve overlap is not
optimum at lower revs - <groan>

HEY - just saw an add for 'Z-Max' is this 'mini-molecule' had anyone
actually believe there are liquid lubricants that have 'smaller' molecules
then metal atoms and expect they are not volatile at engine temps - really ?

The demo looked convincing - lubricatant soaked into metal surface, sounds
like graphite oil.

I remember Bi-tron - just plain chlorinated parrafins <sigh>

Hope there are no network marketing dudes on this group ;-)

Tah - sorry for off topic digression (had an Australian beer) hehe

:) mike

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