(eventually this page will have more information)

Basics

When we talk about “OBD1” GM vehicles, we mean vehicles made from (approximately) 1986 to 1995.  These cars used several different types of engine controller – some have one injector for each cylinder (Tuned Port Injection, or TPI along with the LTx motors) while some have fewer injectors that are placed near the throttle body (Throttle Body Injection, or TBI) instead.  All the vehicles of this generation speak the ALDL protocol for logging/vehicle communication.

For purposes of this guide, “ECM” means Engine Control Module, Powertrain Control Module (PCM), Engine Computer Module (ECM) – terms will be used interchangeably to mean the same thing.

Hardware for OBD1 GM

Overview

94-95 model years are oddballs.  Many of these ECMs support being reflashed over the ALDL interface (e.g. LT1) using TunerCATS.  Some (like the 94-95 TBIs) use a G1 adapter.  Many Grand Prix from these years use the G4 adapter.  Diesels generally use the G5 adapter.

The process for tuning OBD1 GM products is pretty much the same for all 86-93 model years.  First, a “chip adapter” is used to convert whatever the ECM in question needs into a form that accepts a 28 pin EPROM.  Some chip adapters require soldering for installation (G2, G2X) but most do not (G1, G3, G4, G5).  The same EPROMs can be used for all of our OBD1 GM products (except the switching adapters…) which is usually the 27SF512 – C2.

After a chip adapter has been installed in an ECM, tuning can begin.  You can burn chips using a ROM burner such as the BURN1/2.  Alternatively, you can either use the Ostrich 2.0 emulator or the emulation facilities of the APU1 to make changes while the vehicle is running.

Logging from the computer is accomplished using either an ALDU1 or the logging facilities of an APU1.  For 86-94 vehicles, CABL1 is required to connect the logger and the vehicle.  For the 1995 model year, CABL2 is required due to the physically different connector.

Instead of buying the BURN2, Ostrich2 and ALDU1 separately, you can buy the APU1 unit that does the functions of all three pieces in one unit.

Hardware

G1 – “Memcal” style chip adapter (TPI, Syclone/Typhoon, 94-95 TBI, 92-93 LT1, etc.)

G2 – “TBI” 24 pin style chip adapter

G2 GN Style – Grand National Only.

G2X – Multiple program switching version of G2

G3 – Multiple program switching version of G1

G4 – Blue Memcal style chip adapter for some 94-95 vehicles

G5 – Diesel memcal style chip adapter

HDR1 – Header that allows reading memcals in a BURN1/2.  Used to read stock program on memcal ECMs.

BURN2 – Programs chips

Ostrich – USB Chip emulator, allows realtime changes while engine running

Socket Booster – required for use of Ostrich 2.0 in TBI applications.  Can be used instead of G2 adapter.

ALDU1– USB ALDL interface

CABL1– Used to connect an ALDU1 or APU1 and a pre-1995

CABL2 – Used to connect an ALDU1 or APU1 and a 1995 car

APU1 – Combines the functions of the BURN2 (programming chips), Ostrich 2.0 (real time chip emulation) and the ALDU1 in one unit

Applications

This table is abbreviated. If you don’t see your application here, please email us.

* Socket Booster (S_BOOSTER) required for Ostrich 2 emulation and TBI ECMs

If you have excel, you can also take a look at this spreadsheet for a list of what hardware you’ll need with various combinations.

Software

TunerPro RT ( link ) and TunerCATS ( link ) are the two most commonly used software packages for OBD1 GM.

FreeScan is a free datalogger that works with some GM vehicles. ( link )

There is an excellent cross-reference I found with google that lists common ECMs, which mask (software revision) they use and various other useful information.  ( link )

Holden Vehicles

TunerCat OBD1 tuner seems to have the best support for Holden vehicles at this time ( link ) although TunerPro has support for some ( link )

Hardware-wise, the majority of these vehicles use the G1 chip adapter.  Some of the newer vehicles use our newest G6 chip adapter.  We don’t know the Australian vehicles as well as those stateside so we recommend you check out http://www.delcohacking.net for more info on these vehicles.