MemCals Needing RFD Tweeking Before Finding A Home......

[Bruce Plecan]

I have seen a developement memcal (GM) where the last seven (8?) rows of
pins had resistors soldered in, early P4 no add on PCB..  On some of the
after market chips, I think ADS were, they used a jelled over memcal that
was so low that there were resistors rather then the netres in  there.
B



> Thanks for your reply Ludis.  I will peruse the info mentioned in detail
> tonight. You have some amazing stuff at your site!
>
> Just thinking out loud for a moment........I've been disecting a less
known
> but somewhat parallel PCM known as the '7060 (aka 16147060).  I'd like to
> recal it's RFD system simply because 1)it would be a nice challenge, and
> 2)I'm currently delivering almost 4 times as much fuel as what the factory
> had in mind, so, if RFD ever kicked in I'd have a real mess on my hands.
My
> original thought was to simply render RFD innocuous, and carry my cell
phone
> and CAA card at all times, but I later resolved to explore the recal route
> in light of the DIY penchant that we all share.
>
> I've traced my '7060 board, and have identified all MEMCAL, NETRES, RFDA,
> and PMID interactions.  In my case, TPS and MAP presumably create a dummy
> load value thru the NETRES and that signal gets fed into the RFDA.  REF,
> TPS, and CTS are fed into the RFDA and in turn the RFDA would seem to
> trigger the PMID to fire both injector channels in synchronous
simultaneous
> fashion during RFD.  No problem understanding this stuff so far.
>
> However, I get lost when staring at the two black NETRES blocks under the
> SNEF.  I am *told* that one block is a 14 pin resistor network containing
> R1-R15 plus R21, and that the other is a 16 pin resistor network
containing
> R16-R30 excluding R21.  In fact the two NETRES block P/N's are 16144688
for
> the smaller and 16144689 for the larger in my case (from MEMCAL 16175248
BCC
> BAMY5250).  I am also *told* that two of the resistors within the larger
> block will typically be divorced from the rest, and will serve to control
> the hardware moding.  I have located the trace from the output of these
two
> resistors back to the REST.  Otherwise, the remaining NETRES resistors
> *supposedly* are connected in some circuit arrangement that I'm not aware
> of, and work communally to shape the desired crank/run RFD fuel pulses
that
> are delivered to the engine when the CPU is having a bad day.
>
> So, my ponderings now include..........
>
> Q1 - Can these NETRES blocks be replaced by a creative breadboard circuit
> containing multiple cascade resistor devices?
> Q2 - If so, in what arrangement would they get interconnected?   On the
> surface, there would appear to be more resistors than available pin pairs,
> so I am assuming that there is a certain degree of interconnectivity
within
> each NETRES block.
> Q3 - Are there upper/lower "R" limits that a person should be aware of, so
> as to not let the smoke out?
> Q3 - Are the resistors grouped/segregated by function, or will changing
one
> have a dynamic effect upon another?
> Q4 - This thing must have been calibrated by a mere "human" at one point
in
> time working for the OE.  Anyone care to share experiences & thoughts
and/or
> point toward alternate sources of understanding?
>
>
> Thanks;
> Walt.
>
>
>
>
> >
> > Actually, on MAF cars, only TPS and CTS are used.  If you study the
> > wiring harness diagrams for both MAF and MAP 2.8 MPFI's (1226869 &
> > 1226870 ECMs), you'll notice that either MAP or TPS goes to two ECM
> > inputs.  The extra input goes to the RFD chip.  In a P4, the MEMCAL can
> > jumper TPS into a circuit that creates a fake MAP signal.  Look at pins
> > 61, 63 & 64 of the MEMCAL.  Pin 61 provides the LOAD signal to the RFD.
> > 63 & 64 are hooked to the raw MAP and TPS signals.
> >
>
>
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