running lean?

[Tim Rogers]

Khiem wrote:
>>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.
 <snip>     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%.  <snip>
I just checked the fuel pressure; 58 psi with the vacuum line pulled, 49 psi
at
idle (~1100 rpm). <<

The major variable that we are missing here is the fuel pressure that the
injectors were seeing above 6k under full load.
You may want to install a temporary fuel pressure gauge in the cockpit and
have someone read it as you drive at full boost and RPMs.
If you are lacking in fuel pressure under these circumstances, then you
probably have a flow issue caused by a clogged in-line or in-tank fuel
filter, or possibly a kinked fuel line.
This is my gut reaction and as always, YMMV....

Tim Rogers
-93 NX T-top -needs wiring work
-91 NX - Racecar-to-be
-75 Silverado - Rusty Tow Beast