[Diy_efi] Adapting Ion Sensing systems

[Adam Wade]

--- "Daniel R. Nicoson" <A6intruder at adelphia.net>
wrote:

> My point in pursuing ion sensing is the real-time
> control they can provide (or so all the technical
> papers say).

The problem is that ion sensing is not a single thing;
it is a technology that can be realized in many ways,
from primitive to extremely complex.  In theory, you
could do real-time closed-loop spark timing with a
sufficiently sophisticated ion sensing system...  But
the cost would be extremely high, and it would still
require some trial-and-error to get some baselines to
work with.

> As a shade tree tuner without a nice dyno cell,
> optimizing a spark table with aftermarket cylinder
> heads, cam etc. is purely trial and error
> regardless if one just wants max power OR emissions.

That is true of most tuning to some degree, although
there are tools that will allow you to cut that
significantly.  A four-gas analyzer and an eddy
current dyno running "step" tests can tell you a fair
amount about your spark timing, and what you can do to
improve one area or another, without it having to be
all trial-and-error.  Such a setup will speed tuning
of both fueling and spark.

> Worse than trial and error, I have yet to see much
> of a way to optimize spark advance except to
> advance until knock and then back off some.

That doesn't "optimize" spark, necessarily.  More
advance is not automatically better (detonation issues
aside).  Possibly more important are things like spark
location and combustion chamber shape, as well as
things like mixture quality and mixture content.  This
is one area where closed-loop spark control would be
of great benefit, but as I mentioned, the complexity
and cost are exceedingly high at this point, as I
understand it.

> Of course on a boosted application this isn't a very
> good procedure.

And very, very far from optimal (of course this is
true, since holes in pistons are bad for power and
emissions both).

> Anyway, I was hoping someone had stumbled on a
> project that was in the DIY-useful stage.

Someone was working on a project with a MEGA
controller here a bit ago that was purported to have
some level of ion sensing, although I am unclear on
just how complex it really was.

TTBOMK, there are no manufacturers in the auto or
motorcycle world who have the complex kinds of ion
sensing systems on production vehicles at this point
in time.


	
		
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