Newbie needs explanation...

[Barry Tisdale]

Bruce -

Thanks for the reply; things are sort of like I figured.

According to a GM spec sheet I got, BPW (Base Pulse Width) is the *result* of a calculation w/ several multipliers.  Guess I don't understand this, then.  When running a scan tool, I get BPW (units = milliseconds) readings of from zero (on deceleration), to 19 @ WOT & hi rpm.  (I was wrong w/ the 15 figure on my last post).

Are these figures consistant w/ what you'd expect?  The 19 figure came @ 4050rpm, the highest speed reached (this thing shifts @ too *low* an rpm - gotta fix that!).  At this speed, we have 14.8msec/crank revolution - duty cycle comes out to be *more* than 100%...?????  If we figure on two crank revs per power cycle, 19msec / 29.6msec = 64% duty cycle - this makes more sense to me.

Before I start playing w/ this thing, I've got to *understand* exactly what I'm doing and how it works in stock trim - lean mix on a turbo engine can mean sudden death, and I *really* don't want that to happen!!

Thanks again for your time & trouble, Bruce.  I'm a dentist by profession, (hobby = computer process control), not an engine guy - this is a new area to me but should be fun - hipo engines & computers = good mix!

Barry