Simple Injection Questions

[Bruce Plecan]

| Hi Frederic,
|  I gotta agree.  The GMC Syclone has a 4600 RPM fuel cut from the
| factory.  When ya hit it, it bucks like a bull, as fuel is turned off,
then
| back on, and there is definitely detonation when this occurs under
| boost.  I've heard all the theories about turning the fuel off <cleanly>
| then back on, but they don't seem to apply with 16psi of boost..
| There is *significant* detonation as the injectors come back on..
|  It's not pretty.  It would be good if they'd kill both spark & fuel

Ya, but look at the drivetrain inertia your taking about.  Your syclone with
it's 4WD is over twice as much as any other vehicle so when it drops off,
and back on it is violent, and would be under any strategy, IMHO.  Probably
a Saab ATP (?)  Running a boost cutoff, overspeed management, and then a
fuel cut..  Don't let things turn back on at 16 PSI of boost.
   Also, depends on driver.  Hitting a fuel stop in a drag car can mean
something failed, and the run should be aborted.  So the driver ends the run
by lifting, rather than keeping his foot in it.
   I wouldn't use it a signal to shift or to flat foot thur it (not
lifting).
Grumpy

| Mike V
| >  It would be my preference to cut spark rather than fuel, simply
| >  because cutting fuel would result in a lean condition at higher RPMs
| >  and possibly cause detonation.  No spark results in fuel cooling off
| >  the combustion chamber while you're above the RPM limit, but I know
| >  there are other factors (unburnt fuel into the cats, etc).