I don't seldom give up on a
problem, but I came awfully close this time.
Mark
OK;
Mark; (or anybody). Since we both have 20Bs, and both use the EC2
controller, maybe you have a clue for this one. I’ve brought this up here
before, but no solution.
I have all the
latest updates on the EC2, and I have double checked the static timing set at
35o BTDC. From that point on the EC2 is handling the timing
curve with rpm and MAP.
At lower power
levels, disabling the leading ignition clearly has a larger effect than
disabling the trailing – as one would expect. At somewhere around 18”
MAP, (don’t know right now what rpm that is, maybe close to 4000) the effect
is about equal when disabling either set. At higher power levels, there
is a larger effect of disabling the trailing than the leading. That
troubles me. I think the leading should always have a greater
effect. It makes me wonder about the timing; or if something else is
wrong.
I have in the past
tried varying the timing 2 or 3 steps while at power, but couldn’t discern a
change in rpm greater than the normal variation in the readout.
Tracy sent me the XL
spreadsheet with the timing curve data, but I haven’t yet figured a safe way
of checking it with that prop spinning close by.
Does your
installation exhibit the same behavior?
Is there some explanation for this? What test should I
perform?
One thing that
occurs to me is that Tracy measures MAP out
before the runners. I measure MAP at the manifold, downstream from
intake plenum and three short runners and the 3-barrel TWM throttle
body. At WOT my MAP is not atmospheric pressure – it is maybe 2-3” HG
less. I can’t quite see how that is an issue; but maybe someone else
with a TWM TB setup with the MAP port downstream would know.
Other than that I’m
very pleased with the new mixture correction table setup for the 20B.
Much less tuning and seamless transistion between tables and through the stage
point. Probably the pulse clamping and injector isolation diodes are
part of that.