[Diy_efi] going sequentail on a 2-stroke?

[Alexei Pavlov]

sravet at arm.com wrote:
> 
> Alexei Pavlov wrote:
> >
> > No Steve, I think there wont be any problem with RPM.
> > The ECU will think injecting into 2 different cylinders while
> > in fact they will inject in the same one. It's the same as when
> > we use a waste-spark ignition.
> 
> It's not exactly the same.  If the injector signals ever overlap, ie if
> both outputs are driving the injector at the same time, then the
> computer will only be injecting half the fuel that it intends to.

You are right, I did not see that case.

> 
> The time available for injecting is only half what it would be on a 4
> stroke engine.  That's why I say RPM may be a problem.  Some/all of the
> ECM code will be synchronized to engine position.  There will be an RPM
> limit where that code can't finish executing before it needs to start
> running again.  This application makes it worse because in order to use
> alternate injector signals to fire the same injector, one wire for even
> numbered revs and the other wire for odd numbered revs, the computer is
> going to have to think the engine is rotating at twice it's real RPM.
> The 2 stroke motor may be running easily at 3500 rpm while the computer
> is doing all it can to keep up with what it thinks is a 4 stroke motor
> at 7000 rpm.

In fact a sequential injection needs a sensor reving at half of RPM.
A 2T engine does not have it but it could be creater (may be already
available on auxialiary devices).

So the solution would be to use big injectors to never overlap
odd-even injection phases. In this case the ECU sees the real RPM.
300cc per cyl 2T injector is likely the same as one for a 600cc
4T injector. Porsche 3.6L flat6 injectors would fit.
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