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
Guess a little more detail is needed to explain this. The EC2
re-computes the injection requirements in real time. Just
before the intake cycle starts, it computes the required fuel for
this individual intake cycle. You can't get any more closely
tied to RPM than this.
The volumetric efficiency is very much affected by the
design of the intake system. Since there are no two alike out there
(at this time), it is not possible to take VE into consideration as a
function of RPM. Detroit has it much easier in this respect because
they can control every detail of the engine.
Tracy
Ok, one more time for us slow
folks. I understand that the EC2 calculations some "adjustment" to
the fuel requirement for each intake cycle. Since the intake cycle is
certainly tied to rpm in so far that the rpm determines the number of
intake events per unit time. I think I follow that each intake
cycle can be different as far as fuel requirement. I had
assumed that the fuel injection adjusment is primarily based on the
manifold pressure it senses. In otherwords, if the Ec2 senses 17" Hg
manifold pressure at a specific intake manfiold air temp it
calculates X milleseconds of injection time. I had assumed that this
amount of injection time would be the same whether 17" at 3000
rpm or 17" at 5000 rpm but that since the injector fires more times/sec at
5000 rpm than 3000 rpm there would be more fuel injected. In
otherwords, I had assumed that since the EC2 does its calculation for each
cycle, it didn't know(orcare) whether the cydle was happening at 3000 rpm
or 5000 rpm only what the manifold pressure was at each rpm.
Since my assumption is apparently
incorrect, then over a beer, you need to explain it to me one more time
how the RPM is a factor in the computation of fuel injection
time.
I strongly suspected that Ve wasn't
really a factor for the reasons you stated, too bad {:>)
Ed
Anderson