Low pulse width and high duty cycle, or vice versa...

[munsonbw]

Details:
MS1, V3
2.3L 4cyl, 18.3 lb/hr injectors wired in pairs
6000rpm redline

I am trying to tune my upper RPM range with a narrow band o2 sensor, which for me is trying to stay about .7v or so and then plug reading (which I can't seem to do well) and other methods. At first I appeared lean at WOT, 5000 rpm and higher. In looking at the datalog, I was running ~11ms pulse width and 100%+ duty cycle (which I understand is not doing anything over 100%). Some research of the archives turned up that I should switch from all four injectors 2 squirts simultaneous to alternating and 2 squirts. This brought my duty cycle down to upper 60% range, but the pulse width is 25ms and higher. I may be a little fat on the top end now, but excessively so. It seems like the 2 squirts alternating is the only way to get the fuel I need, but I am thinking I need to step up my injectors. To make matters worse, when I hit the accel enrich, the PW shoots to 32ms or something like that... way high.

Should I cut my losses now and get bigger injectors? How are you guys tuning the top end? I am just going by feel and keeping the NB voltage above an arbitrary 0.7V... theory being start rich then tune to lean.

[munsonbw]

Lance,

Thanks for the confirmation. What is a practical limit for duty cycle ant pulse width? I understand that 80%+ duty cycle is pushing it due to the injectors nearly open constantly, but I am not real clear about what happens with high pulse width.

Thanks,
Ben