[Gmecm] Tracker TBI Ignition mystery

[Cowen]

For anyone still guessing:

I checked the timing of my mother's car yesterday, set
the same way (by hand, no light, advance until it
pinged under light throttle, then back it off until it
stops.)  It matched my wife's car.  BOTH of them are
reading about 20deg BTDC at idle, check connector
shorted. (It should be about 8deg)

The check connector does indeed influence timing, so
that's working.  Also, "blipping" the throttle results
in a momentary spark retard (as it should when MAP
increases), followed by spark advance (as it should
when RPMs increase).

Idle RPM is about 750, factory calls for 800.

Sometime in the future I'll confirm the cam timing,
and I'll mechanically check that the TDC mark actually
lines up where it should, although I can't believe
both cars would've suffered the same failure though
(and to the same degree).

I give up.  Two different people checking, two
different guns, two different cars, and ignition seems
to function flawlessly on both of them - except for
irrationally high amount of advance!  The car still
has a very minor driveability issue, so I still think
there's a problem outside of my technique.

Thanks for all your advice folks, this has changed
from what I thought was an EFI problem to an unsolved
mystery.  I appreciate the patience and help from
those on the list who tune in purely for injection and
programming discussion.

There used to be (still is?) a radio program on NPR
called "Click and Clack, the Tappet Brothers" hosted
by Tom and Ray Mariozzi (sp?).  The premise was that
people called in to have their car problems diagnosed.
At about this point in a difficult diagnosis, one of
the "brothers" would ask the car owner "What colour is
the car?"  Whatever the response, a learned "Ah ha!"
(and a flurry of chuckles) would burst forth, as
though that explained everything!

So, in case you're wondering, it's blue.  They both
are.

Duncan

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