Re: Pin functions determined by PROM?

["D. Barry Stubbs" <z24man@earthlink.net>]

Jeremy Gonyou wrote:
> 
> The check engine light wasn't on was it?  This sounds an awful lot like
> back-up fuel mode.  I run auto code in my manual (93 3.1) with no problems.

Yeah, the CEL was illuminated on occasion for the DTC 24 (VSS low), but
I don't think it was in back-up fuel, although I could be wrong. 
FreeScan was reporting about 40d advance at cruise and 20d at WOT,
varying throughout the throttle range.  Commanded AFR was changing too,
but because the VSS field would never get >0, I never saw cruise mode. 
14.7:1 at cruise, and 11.9:1 or something like that at WOT.  Ironically,
the engine felt stronger with this 3.1 code than with the 2.8 code.

 
> >Can a PROM change the function of the input pins on the ECM?  Last night
> >I dropped in a PROM for a 3.1 auto into the 7730 for my 2.8 5spd, and I
> >noticed a few odds things happening.  It seems that the VSS doesn't get
> >to the ECM, causing stalling problems on coasting and DTC 24.  I can
> >possibly understand this because the PROM was designed for an auto, but
> >it also can't read the A/C pressure transducer, so no A/C demand nor
> >clutch control, either.  I dunno how it would have handled the lack of a
> >digital EGR, but since the VSS never made it above zero, I'm guessing
> >that I would not have have found out.
> 
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D. Barry Stubbs                                    http://surf.to/z24man
(912) 745-9429                                     AOL IM: thez24man
z24man@earthlink.net          BNet Member #828     ICQ #5409648
#101DSP MidGa Region SoloII   94 Q4 5spd Aqua Z26  88 2.8 5Spd White Z24
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