TRACTION CONTROL, now INJECTOR OFF wisdom

[ECMnut at aol.com]

Scott, 
 I had the exact same concern when I discovered that my Turbo 4.3 GM
had an RPM limiter that turned off the injectors at 4850 RPM, then back
on at ~4400.  If you leave a stop light and take first gear out too far,
w/16+ PSI of boost, it  kinda makes for a turbocharged 
mechanical bull imitation.  It bucks really hard as the fual
is turned off/on under boost which actually stays high..  If ya 
watch the Diacom, there is detonation caused by this process too.
In theory, if you turn of the injector, the cylinder *instantly* has 
waaaay to little fuel present to support combustion.  The real world
scenario prolly involves the intake event that takes in some residual 
fuel from a previous injector cycle (at least in my case).  The 
detonation was audible as the injectors switched back on at the
lower RPM limiter threshhold...Bad stuff
Although nor directly related to the topic,
what's intersting, is the relatively low RPM limit, which really
was okay with the 4.3's torque curve..  I have 12.70
timeslips from 1/4 mile runs with the stock chip in place.
The 700R4 auto has a loose enough convertor that you can
still muster enough boost at the starting line to overpower
four  245/50-16's then, have it totally run out of power by 
the time the tach reaches 4500.  Proving, that with boost,
you don't always need RPM to make respectable power...
Especially with crummy ports
Mike V


In a message dated 11/12/98 8:17:15 AM Eastern Standard Time, sknight at mich.com
writes:
> Just a question about cutting the fuel at WOT:  Couldn't that be very
>  very bad for a high cylinder pressure engine?  I know my race engines
>  when just a little lean will start to pit the pistons very quickly and a
>  supercharged car will just sneeze.  I've seen many Winston Cup cars come
>  in puffing after they mis-calculate their mileage or get a little
>  greedy.  Maybe that is a totally different situation than taking off
>  from a standing start, but it just makes me uneasy running an engine
>  lean under full throttle.  Does the fact that you are talking about
>  shutting the fuel completely off for those durations mean that no
>  residual fuel will be left over from a previous cycle to give it a lean
>  condition?  Ease my mind please.