The reason Tracy gave for
the ECU not working was because of that set-up, as his Vacuum pick -up
is at the Plenum - something to do with fluctuations within the tube,
whereby the plenum was static or less successful to wild fluctuations.
George ( down under)
I have accumulator and orifice which smooths
the MAP nicely.
Dave said: Besides a slight difference in the mixture
necessary between the 2 computers, both locations seem to work well.
Dave: Mine works well also - except for the anomaly noted. I don’t
know if you mean that yours specifically doesn’t exhibit that phenomenon?
Al, was 35° BTDC Tracys suggested timing?
The 35o BTDC is the static
setting specified in Tracy’s manual; line up the 2-point trigger wheel with the reluctors
at that point.
Quite frankly, I haven't tried the coil disable feature at
high rpm yet. So, I don't have an answer to your question. Heck, I
can't even get my auto-tune to work.
Mark; well, whenever you get that far,
give it a shot and see what you get. Good luck with the auto-tune.
Does anyone else experience these symptoms? That’s the question.
Thanks, guys,
Al
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.
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