[Diy_efi] Can anyone diagnose this engine problem?

Tue Feb 22 17:16:20 GMT 2005

It will do it also when you rev the engine in drive  with your foot on the
brake and rev the engine to see how well the engine takes the load. My 96
lumina would do just as you say come to the rev limet and start cutting fuel
back. As soon as you get VSS pulses the car pulls hard like it should.

-----Original Message-----
From: Rick McLeod [mailto:dunvegan at sbcglobal.net]
Sent: Tuesday, February 22, 2005 10:58 AM
To: A list for Do-It-Yourself EFI
Subject: Re: [Diy_efi] Can anyone diagnose this engine problem?

I have herd a very similar 'audio' from one of my
cars, it has a park/neutral rev limiter that modulates
the injectors anytime it sees RPM in park/neutral
exceed about 3000 RPM.

Therefore, my question: is your injection computer rev
limited? Could it be it came from an application that
is 4stroke low rev?

Just a thought, based on the audio clip, it actually
sounds like everything is working as prgrammed, and
hitting a rev limiter?

--- Bret Levandowski <skishop69 at yahoo.com> wrote:

> We do a few mods with our sleds as well. Though, we
> use Arctic Cats because they're already injected.
> Injectors in the cylinders instead of at the crank
> base aren't as efiicient and generally suffer form
> heat soak. That's why 'Cat moved them to the base.
> I'd hook your injectors up to a good scope and check
> the readings. Also, make sure you've got good ground
> and driver connections. In the video, it sounds like
> the injectors or ignition is cutting out. Since you
> say you've eliminated the ignition, that only leaves
> the injectors. If you're not running an O2 sensor,
> you should consider hooking one up. A wideband would
> be your best bet to monitor if it's going lean
> enough to cause you're problem. Unfourtunately, the
> reason they don't use them on two strokes is the oil
> doesn't react well with them. It should be useful
> long enough to see what's going on. My best guess
> (all though not that great) is that you've got an
> ECM hardware problem or you're injector windings are
> cooking. Ski
> 
> joeld <joeld at ualberta.ca> wrote:
> 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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