Intro to EFI

[Garynick]

Hello, My name is Garynick and I have an engine swapping addiction! During the past few years I have transplanted several TBI and CPI engines and computer systems into vehicles that originally were offered only with carbs. I don't have anything against carbs and points, as I still have several vehicles with those as well. Just an interest in better fuel milage, and a bit more torque that these older cars had ever experienced.
Most of what I have been building so far has been OBD1 based, and while things have worked out well, there is always room for improvement. I'm stumbling through some of the input numbers and learning what changes may be available. Any direction to get me up and programming OBD1 systems fastest would surely be appreciated.
Garynick

[daveosx]

Hey Garynick
I worked at Corvette action center as a DCS rep back in the early 1990s retired from GM in 1995.
I used to have a great Tech 1000 terminal that had a large breakout, a scope, gas analyzer, and Master PROM burner.
When the GM 66ECU came out with OBD1.5 ish we could burn EPROM without swapping memcal
Lots of guys here are reverse engineering some of the stuff we wrote back then.
If you have the ECU with the CAST aluminum case you can program them directly using http://tunercat.com/ OBDI tuner software lots of eprom files there as well.
You will see a lot of guys using the 7247 and 7277 series sheet aluminum case ECU with custom roms.
I went a little different route and I have successfully built a ground up controller using Arduino.
There is a group called Speeduino who did something similar for gokarts and then 4 cylinder port injection.
The after market does not currently have a decent controller for a stock TBI.
I have used the Megasquirt MS3 Module successfully but much of the circuitry I constructed to drive the older injectors.
Tuner Studio software is a favorite among a lot of tuners because of MegaSquirt
I do not care for it so much.
On the system I am developing I am not using table pairs like most.
I have a realtime self tune function and realtime injector calculations.
SO the base line vehicle running is tuned by measuring the displacement and flow rate of the injectors.
The active tune starts at temp 183F and adds a realtime plus minus based off the O2 sensor like an analog lambda jettronic.
If the same self tune is reached a preset number of times (kind of like block learn) based off RPMxMAP the system writes to pram.
At shut down the system recalculates the internal base tune factors clears the eprom and shuts off.
The next start the new numbers are used.
This self tune function repeats as long as there is a differential in the overlay.
Once the minimum train threshold is met it stops writing to eprom to save the eprom life.

The stage I am at with the new ECM is preinstall on board version 2. Health and financial is keeping me from working on the daily driver.
The Trans controller is so simple I have it working for a year now.
A couple of issues that I have unique on the test mule is that someone "shift kitted" the transmission before I got the truck.
SO the transmission PWM main line pressure is fixed high and the Torque convertor lock PWM does not seem to make any difference either.
So my controller shifts as firm as the valve body and clutch paks allow.
Chirps 2,3,4 but not enough to brake a joint.
The other issue I have with series version 1 of the controller design is that I used I2C communication to pass messages between the ECU and TCU and sometimes I get a buffer overrun. Key cycle reset and I keep driving. Version 2 uses 8 bit parallel hardware to communicate between micro controllers.

If my health permits I will be developing a super cheap V8 square bore TBI unit.
I have a setup for coil on plug for GEN 1-3 SBC that I will be releasing.
Also A crank trigger ignition retrofit kit for SBC. One that does not require pulley spacers and machining.
Look at my early post about the new Beagle Bone Controller for LT1 / LS1 working towards that as well.

[Garynick]

Thanks for the reply! I am a true newbie to much of the OBD1 coding and prom changes. I have been working on and tuning cars and bikes for several decades now, just haven't had the need to get an closer within the ECM other than changing harnesses, or merging a few harnesses. Wiring and sensors don't intimate me much, the software is another animal!
Currently I'm going through a '89 GMC K1500 with a stock 350. Truck originally had an automatic transmission, and transfer case. Now that same truck has a manual 5 speed with the transfer case. I'm under the impression most everything can remain the same, other than a signal to the ECM if the truck is in Park or Neutral, and the TCC circuitry. Will it be a simple matter of installing a pre-programed chip into this ECM, and cleaning up some of the wiring, or is there a bit more involved? BTW, the ECM in this truck is a 16125851 ANLW.
Thanks in advance to whatever direction I may be guided!

[daveosx]

Thanks for the reply! I am a true newbie to much of the OBD1 coding and prom changes. I have been working on and tuning cars and bikes for several decades now, just haven't had the need to get an closer within the ECM other than changing harnesses, or merging a few harnesses. Wiring and sensors don't intimate me much, the software is another animal!
Currently I'm going through a '89 GMC K1500 with a stock 350. Truck originally had an automatic transmission, and transfer case. Now that same truck has a manual 5 speed with the transfer case. I'm under the impression most everything can remain the same, other than a signal to the ECM if the truck is in Park or Neutral, and the TCC circuitry. Will it be a simple matter of installing a pre-programed chip into this ECM, and cleaning up some of the wiring, or is there a bit more involved? BTW, the ECM in this truck is a 16125851 ANLW.
Thanks in advance to whatever direction I may be guided!

Yes I think you b\need a different Prom you may be able to find one here or in a junk yard
I believe that it uses the Blue top style MemCal
You will need to either find a STANDARD memcal or have so one burn one.
You will need the VSS signal to the ECM
The other bits I am unsure if a K1500 used the Trans Shift Solenoids or if They had a pre 4l60/80 700R4. If the truck had them then it will set error codes and run in limp home mode.
I am currently working on a TBI specific ECU I will be testing Version two as soon as I can chance having my truck down for a couple of weeks.
Lifes been hard and I have only one drivable currently it has put me on standby for the Version two testing for about 7 months now.
I also need to replace Cam follower adjusters on my STS so it is sitting in the drive.
My WS6 needs an overhaul in the garage

Anyway the goal is to have a CHEAP solution to the TBI EFI orphans out here.
Much of the Tuner world is focused on Port Injection and the old rochester units get minimal choice.
Also been working recently on a clean sheet design of a complete fuel injection controller for 4 barrel injection units that got the PicAx chinese solution. I implemented Wideband and FLEX fuel Today using a Cellphone Cortex 8 at 600Mhz as the calculation unit and ATmega 32U4 as the fuel timer driver. Difference is I am calculating realtime rather than using look up tables so tuning does not require dyno and Tuner STudio/MegaTune or the like. Simple old carb metaphor on a touch screen like jet size and pump cam, pump size, vacuum power valve like an old holley carb. Simple things like setting the idle jets are automated and drive time adjusted via Lambda feedback and FLEX info. Actually only 5 sensors TPS.MAP,Coolant,FLEX and WBO2.