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.