Engine Control Question

[Chris Morriss]

In message <000001be5ee8$74366ca0$02000003 at scottfea.cgocable.net>, Scott
Feaver <sfeaver at cgocable.net> writes
>I have been monitoring my engine with diacom and have found out a few things
>about it..  One of which leaves me wondering why...
>
>Here are the details
>91 Sunbird
>3.1L V6 Engine
>Automatic, 2.53 Axle
>
>When speeding up from a dead stop at WOT, the fuel injector pulse width is
>around 12.2ms.  Once it goes above 3700 rpm or so, it starts to slowly
>decline until it hits 5200 (right before shifting).  At 5200 rpm the pulse
>width is 9.8ms.  Why would this be?  Is this so the engine doesn't melt :),
>or for emissions reasons.  If this stayed at 12.2ms right to the shiftpoint,
>would this generate more power?
>
>Also, this thing has the 730 ECM.  How many frames per second on this baby?
>(I asked this before, but now know exactly what to specify :)  Has anyone
>found out anything about the MEMCALs for this ECM?  I have the eeprom loaded
>in if anyone wants to take a look..
>
>Thanks,
>Scott
>
I would guess that the peak torque rpm for you engine is at 3700rpm.
Above that figure your volumetric efficiency will be falling off, so
that there will be less air drawn into each cylinder on the induction
stroke.  The pulse width will be decreased to keep the air/fuel ratio
correct.
-- 
Chris Morriss