Good explanation and I agree with everything except the part about RPM not being used by the EC2.  Engine speed is a primary input to the system, hence the term "speed - density system".  

 

Ok, if I understand you correctly, Tracy,  then RPM IS a  computational variable in determining fuel injector pulse duration and not just the "frequency of injection" factor.  Is RPM an adjustment for "Volumetric Efficiency" at different rpms or used for a different purpose??

 

Ed

 

After giving it some more thought, I think the long distance between injector and port has a large part to play in this problem.  It causes the fuel delivery to the engine to be out of phase with what the engine is doing. 

 

 At very low throttle, the volume of air in the runner can represent almost all the air that the chamber is going to inhale in one cycle. Since the injection pulse calculated and injected for that cycle is at the far end, the engine is not actually going to get that load of fuel until the NEXT cycle.  If conditions are changing rapidly (which can definitely happen at low rpm) the charge for one cycle can be very different than for the next one. 

 

In addition to this factor, the injected charge is sitting in the runner waiting for the next cycle and has a chance to condense on the walls of the runner.

 

These are the factors that made me advise against moving the injectors out to the far end of the runners.

 

 

Tracy