Re: 7749 guru needed....

["nacelp" <nacelp@bright.net>]

> I'm in dire need of some assistance w/ my current project, bigger cam &
> heads on my Sy.  Problem, naturally, is reduced vacuum @ idle

Big changes, yes

& part
> throttle,

Shouldn't be too bad.

so's I've got to make some chip changes.  I've got 3 bar chip/MAP
> sensor & using Promgrammer98 & have complete ALDL data logging & reading
> setup.  I've done some chipping, sucessfully changing such stuff as idle
> speed & EGR disabling, but I'm coming up empty here.
>
> I thought I'd go about it slow & easy, learning as I go.  First thing I
> want to tackle is the idle, now about 14"Hg (50-55kPa), @ 750 RPMs.
>
> Integrator at idle, warmed up & in closed loop, reads high 80's.  Means
its
> cutting fuel, meaning (to me) tables specify too rich an A/F ratio, VE
> being too high.

True

> Been working w/ the F29 table (the one @ 0476), VE vs. RPM & MAP, Closed
> Throttle.  Seems to me, the numbers @ the upper left of the table are the
> critical ones here, 600 & 800 RPMs @ 20-30% MAP.  I'm assuming that the
MAP
> figure is given in percentage, and idle is gonna be right down at the
> bottom of the percentages, so these four cells are the important ones.
> I would expect reducing these figures, (VE) would reduce fueling, and
cause
> the Integrator values to rise.  However, I can take these 4 numbers right
> down to zero and the Integrator readout is unaffected.

Sounds like the ecm isn't seeing idle, or in anti-stall, or just way out to
lunch calibration wise.
BE ABSOLUTELY sure everything is RIGHT mechanically.  All the grounds where
they should be clean etc.  Next hoses, are they all perfect (still ising
that dentist stuff?).

> After I do the idle, I've got to do off idle, which is *really* terrible
w/
> the new cam - stumbling, backfiring & knock on light throttle application
> (O2 is in double digits).

Ya got to coordinate the two, and do some of each as you go, once ya get a
half decent idle.
>
> BUT - gotta learn to walk first; there's no cause & effect relationship w/
> my idle correction attempts, so I'm not going to attempt to correct
> anything else until I understand how to do things here.
> Any suggestions from the gurus out there?  I'd really appreciate any
> assistance w/ this!
> Thanks - Barry


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