copied from another website and I believe it's from the Suzuki M109 site. Might be some differences when used on Harley engines but principles should be close to the same.
"Well, I emailed Cobra yesterday asking some specific questions that were basically the same questions you guys have been asking about here.
This is the response I received.
To answer some of the questions that have been posted here. It seems it use the measurement of how hard a cylinder
accelerates the crankshaft as a way to correct fuel mixture."
"thanks for your questions and for your forum's interest in the new
Fi2000 PowrPro Tuner. This really is a phenominal product in every way. And
how it works through its Patent Pending technology is really quite simple.
But it's difficult for people to grasp because previous Fi tuning products,
even so-called auto tune units, were headed in a completely different
direction. What we've done is taken all the data that you get from a dyno
and sourced it from the motorcycle itself, then made almost instantaneous
calibrations to achieve the best power/acceleration.
I've provided some information below taken from a section of a white-paper
that we've developed to help people understand how this product works, and
why it works so well.
But remember, this only corrects fuel. It does not correct poor product
choices or combinations (say a high flow air filter with restrictive exhaust
pipes). It does not alter timing. And the Continuously Variable Tuning
feature works under acceleration only. So I hope the following information
helps your forum members understand how revolutionary this product is.
When a cylinder fires, it accelerates the crankshaft slightly. Every engine
has some kind of torsional shock absorber between crank and gearbox, which
is there to accommodate this slight variation in crank speed. With
the application of modern high-speed electronics, we access this information
and time the rotation of the crank from one firing to the next, and analyze
whether the next firing is slightly stronger or weaker than the previous
one.
Now comes the clever part: using the measurement of how hard a cylinder
accelerates the crankshaft as a way to correct fuel mixture. If the mixture
is a bit lean and our system adjusts it to be a bit richer at the next
firing, more power will be produced and the piston will give the crank a
slightly stronger kick. We can use this as a tool to move from whatever
fuel mixture the engine is actually receiving, toward a more efficient
mixture.
The next step is a way to time the rotations of the crank, so crank speed at
one firing can be compared with crank speed at the next firing. Fortunately,
bike manufacturers give us this info for free<as the time from the beginning
of one fuel-injection squirt to the beginning of the next one, 720 crank
degrees later. Yes, the engine¹s other cylinder may be slowing the crank by
being on its compression stroke, but all we need is comparative information.
We also need to experiment with fuel mixture, just as race tuners or EFI
programmers do. If we make the mixture a little leaner and the next crank
cycle takes a little bit longer than before, we know we¹re going the wrong
way. This is just like what old time race tuners did by changing carburetor
jets and then looking at the bike¹s quarter mile ET or lap time. However, in
the case of the Fi2000 PowrPro, this process now occurs up to 80 times per
second<it¹s literally Continuously Variable Tuning.
The Fi2000 PowrPro conducts its fuel-mixture tuning by varying the mixture
slightly. If the crank moves a tiny bit faster when the mixture leans out
slightly, the PowrPro knows that¹s the right direction and the system leans
the mixture again<or vice-versa. With a big twin cylinder engine turning
5000 rpm, one cylinder is giving us 42 of these opportunities to tune fuel
mixture every second. The result is that the Fi2000 PowrPro continuously and
quickly drives fuel mixture to the value that gives best power. This process
allows the system to adapt to any engine modifications you make. It¹s like
going to the drag strip with a stopwatch and boxes of carburetor jets more
than 80 times every second.
When this system was still in its initial planning stages, one option under
consideration was to use this data to create a new conventional fuel map
similar to the one programmed into the engine¹s stock E FI, and then to
periodically update it. That turned out to be unnecessary because
Continuously Variable Tuning does the same job without the expense and
complication of storing, updating and retrieving data to or from a fuel map.
CVT is a continuous mixture-correcting process, not a fixed set of values
³in a can,² like that of the stock EFI system or previous EFI tuning
systems. Instead, CVT operates continuously every time the bike accelerates."
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Topic: Cobra Fi2000 PowrPro Tuner (Read 10065 times)