PIS firmware is a replacement firmware for the GM #1227808 and compatible P4 variants. This software was
designed and created by Jason Roughley pis.controller@gmail.com and is licensed under the GNU GPL3. Thanks
for taking a look and I hope you enjoy.

Regards
Jay

COMPILING
PIS requires the GCC cross compiling tool chain for Motorola 68HC11 based cpu. The Makefile contains
default paths for the toolset on my system and you may need to override their paths to match your system.
This can be done easily on the command line by executing the make command. i.e.

make CC=/usr/bin/m68hc11-gcc LD=/usr/bin/m68hc11-ld AS=/usr/bin/m68hc11-as OBJCOPY=/usr/bin/m68hc11-objcopy

The usable image will be in Motorola s19 SREC format and is called "delco.s19"

BACKGROUND
PIS firmware is designed to make the 1227808 ecu perform as a more generic unit and is intended for
alternative EMS projects NOT a direct replacement for your road car. The main fuelling algorithm is simple.

MAP only
A base pulse width is chosen from a 16 x 16 table with editable RPM and MAP load points.
Corrections to the base fuel pulse are then calculated and later applied:-

1. Engine temperature correction
2. Engine manifold air temperature correction
3. Wideband EGO correction

Pure Alpha-N or blending
Alpha-N can be chosen to operate alone or configured to work in combination with a MAP sensor by blending
the calculated fuel and ignition tables. The Alpha-N tables are by default 16 x 10, RPM vs. TPS % load
points respectively. The algorithm used with this setting is to acquire two base pulse widths each from
the 16 x 16 MAP table and the 16 x 10 Alpha-N, these values are then interpolated based on two chosen RPM
points the lower being 100% of the Alpha-N pulse width and the upper being 100% of the MAP pulse width.
This final value then has the temperature and EGO (once map mode is reached) corrections applied.

Ignition timing follows this same scheme excluding EGO correction.

BOOST
Boost control is a somewhat crude on off solenoid switching that will oscillate around a set MAP pressure
by a chosen hysteresis value. The good part is it's attached to your foot. A 16 x 10 table, RPM vs. TPS %
determine at what MAP pressure the valve will open, closing again once this drops by the hysteresis.

IGNITION
Fuel and Ignition in the ECU are managed by two IC's. One being the Motorola cpu that executes the code on
the memcal. The memcal code manages the decision of what fuel and ignition timing is to be commanded, whilst
the second IC (not hacked) performs the actual delivery. The second IC receives the ignition pulses from
the outside world and only passes information about fuel injection events it has made. Therefore at no time
do we see the ignition pulses. We are given the reference period between pulses, and if the injectors have
been fired since we last checked. The second IC is configured via the resnet on the memcal.

The memcal can be configured AFAIK in 8,6 4 cylinder and TBI modes via the physical resnet. In each of the
cylinder modes the second IC divides the engine's expected full cycle pulses in half and injects on every
division thereof. Therefore Injection can be set to pulse every 4, 3, 2 or 1 in TBI. Due to the fact that
we hear about every one of these events we can opt to command zero fuel causing skips. I.e. an 8 cylinder
resnet and skip 1 (every second pulse) would inject only once per full four stroke cycle into a V8.

This relates to ignition control because the ECU has to "see" a certain number of pulses to allow correct
fuelling. Herein lays the hack, in TBI mode the ecu will fire every time it hears an ignition pulse allowing
us in combination with skips and an ignition system that tells lies to ecu to become rather flexible.
Imagine a 36-1 wheel driving the ignition and the ignition only ever telling the ecu about two pulses, say
the missing tooth, add in a skip and you'll shoot fuel once every full engine cycle. The code inside the
ECU allows the real RPM to be calculated whilst the second IC is fooled :) every ignition pulse received by
the second IC will cause it to put out the dwell / timing signal which the smart ignition system can
capitalise upon.

CLIENT SIDE
MegaTunix cross platform tuning software is under development to match the delco :) Thanks very much to
David J Andruczyk. Please refrain from contacting Dave for support but be sure to thank him for his great
efforts and software. Thanks for understanding.

VISIT
http://www.github.com/Torture
http://megatunix.sourceforge.net
http://www.diyefi.com
http://www.delcohacking.net
http://www.thirdgen.org

THANKS
VL400, Antus, Dave J Andruczyk (MegaTunix), Fred Cooke, and all the people that made the original hac files
and details available, ludis and all the other hackers 