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Tuning OBD1 Systems

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  • Tuning OBD1 Systems

    This guide is going to focus on the basic, as well as intermediate information of tuning GM OBD1 ECU's used in 60 V6 vehicles. Notice, 94-95 OBD1 vehicles are mostly unsupported. Only the 94-95 DOHC have a removable chip and some support, albeit not much. The 94-95 A body 3100 also has some MEMCAL chip setups, and Tuner Cat is the only known definition for tuning it. I recommend getting a Megasquirt or other aftermarket computer if you have a 94-95 3100 engine. You could also convert to OBD2 or a better supported OBD1 computer.

    What is tuning?
    In the old days, when one said they needed a tune, they were often referring to adjusting the carburetor, cleaning or changing the plugs and wires, replacing distributor cap/rotor, adjusting points, changing dwell, and all that fun stuff. With all the advancements in technology such as fuel injection, DIS (distributor-less ignition systems), electronic controlled transmissions and much more, there needed to be a way to control everything. We needed to have sensors: TPS(throttle position sensor), Crank Sensor, Knock Sensor, O2 Sensor, MAP Sensor, etc...
    Today's Tuning!
    Chip tuning refers to changing or modifying the contents (code) an EEPROM chip in a car's or other vehicle's electronic control unit (ECU) to achieve better performance, whether it be more power, cleaner emissions, or better fuel economy. We'll talk more about this after.
    Why Tune?
    From tuning a car straight from the factory, or you just finished that haul'n 3400/3500 hybrid project, you will benefit from tuning! Lets say you just put in that performance cam, started up the car and now all of the sudden it smells real bad (rich) and just wont idle very well. Whats wrong? Well, the factory EEPROM has been set up for a factory motor, you just effectively changed the volumetric efficiency of your motor. The motor now wants more or less fuel at certain RPM's. It is time do some datalogging and see what your car is telling you
    What is datalogging?
    Data logging is an essential part of the tuning process, it is your eyes, it allows you to see whats going on in that little brain of your car, the ecu. Your vehicle has a port called a ALDL usually under the dash, that allows you to hook up a cable to the ecu that has a built in adapter, that goes to your laptop. on your laptop you can run some free programs that communicates, and interprets the data sent through the cable to your computer for you to see in real time in a fancy GUI (graphical user interface). there are separate programs you can use that are compatible with different ECU's some have scanners and chip tuners built into one app, some are separate scanners, and separate tuning program. As i mentioned, certain ECU's have different applications that are only compatible for that ECU.
    What ECU do i have?
    The next page will help you identify what ECU you have, and give you some detailed information on the specifics of that ECU and some common knowledge you will need to know when doing tuning. When you have identified which ECU you have, you can return to this page to go on to the next step.
    Identifying ECU's
    What Applications do i need to scan and tune?
    ALDL Cable
    Chip burner. Currently $85.
    Adapter (for 1227727/1227730 style memcal chip)
    Freescan (scanner) for 91-93 3.4 DOHC and 91-94 3.1 VIN T
    • Set Status Window to Hide
    • Select proper COM port (mine is 4)
    • Set MS delay. P3-800 works at 1, P-100 works at 50-100. 25-50 should be perfect
    • Freescan Operational Mode should be set to interact
    • Click Force Data. If it doesn't work the first time, wait 3 seconds. Clicking it too fast will lock up the program.
    • Start CSV logging when you are ready. Make sure you stop it before you close the program, or there will be nothing in the file

    Alright, now that we have an idea of why to tune, let's get into modifying the code. If you still aren't sure you are ready, check out our ever growing Tuning FAQs to hopefully answer your questions.


    • SappySE107
      SappySE107 commented
      Editing a comment
      Needs updated! Links are broken for freescan and all moates products. Also, tunerpro can scan most of our OBD1 systems.
    Posting comments is disabled.

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