EFI, MAF & turbos: Update

[Daniel Houlton]

I was able to do some more testing on my turbo install.  I had
asked before about the problem I was seeing where the mixture
under boost would go full lean (drop completely off the A/F meter)
when the ECM went to open-loop under boost when the WOT switch
kicked in.

I did some tests by diabling the WOT switch and it did indeed 
prevent the mixture from going full lean although it was no longer
rich under heavy load or transient conditions.  Makes sense I guess.

Hooked the WOT switch back up and hooked up my multimeter to 
one of the fuel injectors to measure the duty cycle.  At an idle of
850 rpm, the duty cycle was 2%.  I then took it out on the freeway
to see where the duty cycle reached 80% and 100% so I could better
estimate how much more fueling I'm gonna need.

I found some surprising things.  First off was that WOT on the 
freeway did not cause the A/F ratio to go full lean like it had 
been before.  At least not all the time.  After a bit of testing
I found that it only went full lean if I went to WOT (and the ECM
went to open loop) while the rpms were *under* 3000.  Over 3000
rpm and I could go to WOT and the mixture would stay rich all the
way to 5000 rpm.  This was the first time actually that I've been
able to do a full throttle test to see where the max boost was as I
hadn't hooked up the A/F meter before and didn't want to chance it.

At this point, boost had stabalized at 9 psi and the injectors reached
100% duty cycle.  5000 rpm is also my peak horsepower so based on 
this and my stock 120 hp I was making about 190 hp.  It looks like
my injectors are a bit larger than I had thought.  I had figured 
them at 21 lb/hr from some other sources but to flow 190 hp at 100%
duty cycle they'd need to be about 26 lb/hr right?

So I'm curious about that 3000 rpm mark.  I was re-reading parts of
my "Maximum Boost" book and I picked up on something I hadn't noticed
before.  My stock EFI is sequential port injection.  According to Corky
Bell, most (all?) seqential systems revert to non-sequential at 3000
rpm.  Could this somehow be related to my WOT/full lean problem below
3K that I originally asked about?  How can I tell if my EFI is indeed
switching to non-sequential at 3K?

thanks
--Dan