running lean?

[spdracer@mail.utexas.edu]

First, a little background.  T25, s3 cams, jwt ecu...  I was hitting 95%
injector duty cycle at STOCK boost.  Not good.  Plugs looked very very white if
I got on boost.  So.... about 2 weeks ago, upgraded to 4 bar program, Nismo FPR
set at 58 psi with the vacuum line pulled, walbro pump, bored MAF.  Stock boost
hit 80% injector duty cycle, 12 psi hit 90%, plugs are nice and tan.  All is
well.

Went to a little track event with friends; rented out this small road course
(~1.x miles long).  We were doing 5 laps and 2 cars on the track at a time.
First time out, everything is good.  Second time out, the car starts misfiring
above 6k.  Hmmm.. strange... hit the peak recall on the techtom, 100% injector
duty cycle!  Hmm.. strange... only running stock boost so it should've only hit
80%.  That morning before the track, I had switched from heat range 6 plugs
(which came out nice and tan, I'd been hitting 12psi the night before too) to
heat range 7.  Pulled the plugs after the misfiring, very very white.  Hmmm...
strange... I had to shift around 5-6k to avoid the misfiring the rest of the
day.

I just checked the fuel pressure; 58 psi with the vacuum line pulled, 49 psi at
idle (~1100 rpm).  I guess the next thing I have to check is the timing.  Any
other ideas?  It's raining today so I didn't really get on it on the way to
school, but seems to be running fine.  And I looked at the plugs again; though
still mostly white, they are getting tan.

Khiem