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

[Walter Sherwin]

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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