Introduction
This guide is going to focus on the basic information of tuning GM OBD1 ECU's used in 60º V6 vehicles. Notice, 94-95 OBD1 vehicles are mostly unsupported, except through a conversion to OBD1 using a 16149396 PCM. Only the 94-95 DOHC have a removable chip and some support (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.
What is tuning ?
In the old days, when one said they needed a tune, they were often refering to adjusting the carburator, cleaning or changing the plugs and wires, replacing distributor cap/rotor, adjusting points, changing dwell, and all that fun stuff. With all the advancments in technology such as, fuel injection, DIS (distributer-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, MAP sensor, ect...
Todays Tuning !
Chip tuning refers to changing or modifying the contents (code) of 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 if you just finished that haul'n 3400/3500 hybrid project, you will benifit 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, and you just effectivly changed the volumetric efficiency of your motor. The motor now wants more or less fuel at certain rpm's, so it is time to 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 hehe
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 adaptor, that goes to your laptop.
on your laptop you can run some free programs that comunicates, 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 seperate programs you can use that are compatible with different ECU's
some have scanners and chip tuners built into one app, some are seperate scanners, and seperate
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 tot he next step.
Identifying ECU's
What Applications do i need to scan and tune ?
ALDL Cable
http://aldlcable.com/sc/details.asp?item=aldlobd1u
Chip burner. Currently $85.
http://www.moates.net/product_info.php?cPath=31&products_id=197
Chip for all P4 ECMs
http://www.moates.net/product_info.php?cPath=31&products_id=39
Adapter (for 1227727/1227730 style memcal chip)
http://www.moates.net/product_info.php?cPath=31&products_id=32
Freescan (scanner) for 91-93 3.4 DOHC and 91-94 3.1 VIN T
http://andywhittaker.com/files/freescan_210.exe
- 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
TunerPro RT (Scanner/Tuning Program for most GM applications) Version 4.14
http://tunerpro.net/download/SetupTunerProRT_v414.exe
Tuning
Getting started with TunerPro is fairly easy. If you followed the instructions given to you by ALDLCable.com, then you should already be almost done. The next thing you need to do is find the XDF or ECU that is used to tune your specific ECU/PCM. As an example I will refer to $DF a lot, since it is one of the most popular and well documented codemasks used by our cars. Heading over to the TunerPro website, you'll find a wealth of information and some of the most common XDFs used. On the right side of the page, go to downloads, then to definitions(since that is what XDFs are, they “define” where everything is in the BIN). Unfortunately, at this time there is no XDF for $DF up at the time this article is being written, so here is a link to the most thorough version I've seen, which interestingly enough is in the download section of this site... (http://60degreev6.com/forum/local_links.php?action=jump&catid=8&id=46 ) Right, now that its downloaded, its time to select it, meaning go to the top of the tunerpro screen, and select “XDF”, then “Select XDF”, simple right? Then just go to whatever location you downloaded it to, and select it.
BINs
Those are the actual pieces of code that run your vehicle. Without them, you're not going to accomplish anything. Now if you're lucky, someone will have already extracted the BIN you want to work with from their EPROM, but if not, you'll need the BURN2 from moates.net and the HDR1 as well, as they make pulling the BIN from the EPROM both possible and easy. But that's a lesson for another time. I'm more interested in describing the fun stuff. Now for my example, i'll be using a $DF BIN, since i'm using a $DF XDF, make sense? For simplicity's sake, lets keep using files from this site. (http://60degreev6.com/forum/local_links.php?action=jump&catid=5&id=11 ) Now this is BHAK, which is meant for a 91-93 W-Body with a LQ1, and an automatic transmission, and also uses Federal Emissions equipment. Generally, when you start tuning, you'll want to find the most recent BIN that fits your application, since there are small but significant changes that are made from the earliest tunes to the latest, most of them being changes that improve drivability, especially in extreme conditions, such as living in a climate that is normally -20F, or living at very high altitudes. Now you can choose to use the newer BIN than what your vehicle has, or you can see exactly what differences there are between your current and the newest bin using TunerPro, using the “difference tool”. Since this is probably new to most people, only search for differences in defined areas, and then you can choose to copy the newer values into the older tune, essentially making it new, and avoiding possible problems like your A/C not working...
Actual Tuning
IMPORTANT: WHEN LOGGING, MAKE SURE YOU ARE AT FULL OPERATING TEMPERATURE, IF NOT, THE INFORMATION THAT YOU RECEIVE FROM THE ECU WILL NOT BE VERY USEFUL UNTIL YOU KNOW WHAT YOU ARE DOING. That information will be useful for tuning the warm-up tables if necessary.
Now that you have everything necessary to start tuning, you need to know what needs changed. The FIRST thing that needs to be changed is Fueling... trust me if you start anywhere else, you will
chase your tail trying to figure out what you did wrong... now fueling should consist of three tables, and with this specific XDF, you'll need to scroll about halfway down through the list of tables/functions until you get to:
Fuel
VE Table
Idle VE Table
Base VE Table
Those are the three things that affect fueling that you will have to deal with. Obviously, like it states in its name, idle VE only affects you when you are idling or at a very low speed (<2MPH, although
the value is able to be changed). VE Table is in effect whenever Idle VE isn't. Base VE is ALWAYS being referenced. The way the PCM sees it is that it determines to use idle or regular VE tables, it then adds whatever value the base VE table has to the table being used to determine how long to hold the injectors open. Not the way I would have chosen to make the system, but we adapt to it. Now how do you know if you need to change anything? You look at your datalogs, which should display the MAP/RPM and BLM/INT values necessary to know what needs changed. Alternatively(and the way that I suggest), you can use fueltrim to determine what changes need to be made. Based on your datalog, it will generate a table showing you how much the VE table needs changed and where. Nice, isn't it? It usualy only takes 1 or 2 tries to get the BLMs acceptable, but some further refining may be needed depending on your exact setup, which is what i'll try and describe how to do. The way to determine what needs changed is to look at your BLM and INT values. If your INT is set at/close to 128, your PCM knows how much to change the fueling, because the BLM gets moved around by the INT. Should the BLM be 105, and the INT is 128, then take 105/128, and you'll know exactly how much to change the table. In our example, we would be running 21.9% rich if it weren't fot the oxygen sensor to correct it. So we multiply whatever cell correspondes to this reading at by .82 and we'll have a value that should be correct. If the oxygen sensor is going bad, then there will be issues.
Spark
Now, we move on to Spark Advance. Now we scroll up the tables to about ¼ of the way from the top. You should see:
EST
Main Spark Advance VS MAP and RPM
That is your main spark table. There are many other tables that will affect the final value, but this is the table we will focus on since it is the most basic. Now when it comes to spark advance there are
many thoughts as to the correct amount of advance, but some require far more equipment than i will ever own, and unless you have a dyno sitting around, you won't either. The simplest, and what i
believe to be the correct, method for tuning without the aid of a dyno is to advance the spark as much as possible without knocking. Now this will take a lot of trial and error, but it will allow you to get the most out of your vehicle. Double click on the table mentioned, and look at the graph, notice how it is somewhat smooth, and how it raises and lowers in specific places? Well think of that as a pattern, because even though the factory table is probably pretty good for a factory motor, its not perfect, and most of us aren't running factory motors... obviously there are a LOT of things that play into how much advance is possible, but the number one thing is compression. Lots of it, means a lot less spark, or running a much higher octane fuel, your choice. Another major factor is how efficient the heads are: more efficient means less spark. While some old iron heads from the 80s could run as much as 40+ degress of spark, modern well-designed aluminum heads can run as little as 20* in the same cell, yet make more power...think about that for a moment, then lets move on. Now getting the most out of your motor through spark is easy but time consuming: Advance as much as possible without knock. Now the easy way is to take your entire table and advance it a few degrees. Drive around and see if it knocks anywhere, if it does, then you'll know where it has hit a limit and where it can be improved. Obviously knock is bad, so don't accelerate the problem by going WOT at every opportunity. Taking it easy and logging will get you the information you need. In some PCMs there is a TCC retard table, meaning when the TCC locks, it knows to retard it this much to prevent knocking since when the TCC is locked, it puts a greater load on the motor, meaning less advance is possible without knock.
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