MemCals Needing a Good Home...

[Peter Gargano]

ae2598 at wayne.edu wrote:
> 
> Has anyone been able to come up with a pinout and/or internal connection
> diagram for the netres?  

Check Ludis's 1227748 page 7 schematic and compare it with another P4
schematic that uses a MemCal - it'll be clearer then.

> And while we're at it, could someone explain HOW
> a resistor network provides a malfunctioning ECM with the ability to "limp
> home"?  

The RFD (Redundant Fuel Device) - U18 on that schem. takes the NetRes info
and produces the INJLIMP signal - this is used by the FMD (U3) when the
CPU's out to lunch for whatever reason. That drives the INJOUT signal.

As for spark, the DIS (or other spark control device) takes over when
it doesn't get any valid signals from the brains.

> Maybe I'm just misunderstanding the function of limp home mode,
> does it require that the hardware is OK, but the data in the PROM is
> corrupt?

Enough of the analogue HW, including the NetRes part of the CalPac, must
be in place for limp mode to work. Limp mode is what you get if the Analogue
stuff is okay, but the digital stuff has some problem. It also assumes
that your MAP (well, load sensor), CTS and TPS are also working.

Peter.
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