[Diy_efi] Can anyone diagnose this engine problem?

[joeld]

Ok, been trying to figure this out for far too long. Maybe someone on here can 
provide some insight.

What we've got:
-polaris 600cc 2-stroke 2 cylinder snowmobile engine bottom end
-our own billet cylinders and head
-injectors in the cylinder walls
-running a motec M4
-centrifugal supercharger
-45psi fuel pressure
-88pound/hour injectors

What its doing:
It will rev up and idle perfect, right to 4500rpm or so and then it surges, as 
can be seen in this video http://www.putfile.com/media.php?n=100_0008 . When 
it is surging, I am holding the throttle steady.

We've tried timing, all sorts of fuel map changes, fuel pressure, 3 different 
crank sensors (2 magnetic and one optical), adding fuel with a squirt bottle 
right at the supercharger, running without the supercharger. Nothing changes 
at all. We are totally stumped. Its not the rev limiter, we've ruled that out 
as we have it set at 18,000 and it sounds different when it cuts in. Even the 
motec guys have no answers yet. Does anyone here have any ideas? This is a 
university SAE project and we have to go to competition in 2 weeks.

Thanks,

Joel Day
4th Yr. B.Sc. Min Eng
2004 C.S.C. Project Coordinator
Home: 780-434-9294 Cell: 780-722-5376
C.S.C Team Website: www.ualberta.ca/~uacsc

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