749 O/L idle help needed.....

[Bruce Plecan]

I had the same thing on the ecm bench.
Can you send a .gdf of it?.

Have you ever tried the min IAC setting?
ie, engine off, turn idle speed screw in 3/4, burn a chip with idle speed
set for 550 in Drive 600 in Neutral.  Tryyyy it.  May have to tinker with
min setting, but all you want is a min idle speed, and min IAC counts, ya
know just for grins <g>
Bruce




> Gentlemen:
> Trying to get a *solid* idle in my Sy -
> Oxy sensor set @ 0 time (therefore open loop always)
> Timing table set flat in the idle area - this is working - no timing
> variations
> A/F closed throttle table set flat in idle region; VE vs RPM table set
flat
> in idle area.
> Still, the BPWs fluctuate from, say, 1.09ms to 1.25ms.  IAC shows no more
> than 50 +/- 1, timing = no variation, idle speed from 650 to 750 (target
is
> 725).  Idle is best @ 1.25ms here, something trying to lean it out.
> MAT =~ 90F, coolant @ 160F - want steady warm idle first, will work on
cold
> later.  Manifold vac steady @ 16" +/- 1/2 (mild cam).
> *Something* is causing the BPWs to vary, almost like its still in C/L.
> Any suggestions?  Obviously, I'm overlooking something here, but I don't
> know what.
> Thanks - Barry

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