Getting Started With ECM Tuning

burn · Last edited by burn on Wed May 03, 2006 8:09 am; edited 17 times in total

So ive noticed lately there has been an outburst of people looking to get into ECM tuning. Now by no stretch of the imagination do I feel I am an expert in this field, but I have collected an extensive amount of information while tuning to run the MultiTec2 injectors with my 3400. Here is a little outline to get people started and help answer some of the easier questions. First and foremost, if you have a 4cyl, I am not aware of how to diagnose / tune without swapping to the V6 ECM. Im sure there's a way, I just dont know of it.

ECM / MEMCAL:
First and foremost, you need to be aware of what ECM & MEMCAL you are running. for a 2nd gen J-body, there is about a 99.9% chance that you already have the correct ECM. To check, pull your ECM out and there will be a sticker on it. The ECM's model number should end with either 727 or 730.
Now, depending what year your car is can affect the MEMCAL, which in turn affects wether you can run the diagnostic software. A 91-94 MEMCAL uses the A1 definition on its eprom. The eprom is the actual chip inside of the memcal that the data is stored on. The definition basically is the format in which the data is arranged on the eprom. If you have a 88-90 MEMCAL, then you have the 6D definition, and EFILive & freescan wont understand it. But have no fear, as long as you have an analog dash you can grab a memcal from a 91 J-body with the same trans and swap it in and your good to go.This is what a MEMCAL looks like:

Now im sure there is a way to log / modify a 88-90 code, but it cant be done with FreeScan & GMPCM which are the programs I use.
If you have an 88-90, and choose to go the route I described by swapping to a 91 memcal than have no fear, you dont need to go hunting in the junkyard for that exact setup. You can just get any memcal, and put the rewritable chip in and download the 91 bin and burn it to the chip. Its the exact same thing as getting a chip from the yard. Your gonna have to make a rewritable MEMCAL eventually, might as well get it out of the way now.

Diagnostics:
Now, before you can even start tuning, you need to know what your car is doing, and what its not doing. To do this we use an ALDL adapter. they are extremely easy to make yourself.

Here is the wiring schematic to make your own:

You will need:
1 x MAX232 chip
1 x 1K @ .25W resistor
1 x 1N4148 diode
5 x 4.7uF @ 25V capacitors
1 x printed circuit board
1 x 9 pin male com port connector
buncha of misc wire

The parts can be bought from www.digi-key.com and these are the part numbers:
MAX232ACPE-ND <- MAX232
493-1056-ND <- capacitor
1N4148DICT-ND <- diode
1.0KQBK-ND <- resistor

You will require a program such as freescan or EFIlive to run on your laptop to read the data coming from your ECM via the ALDL adapter. I personally recommend freescan since it is free, and it gives more useful information. If your not serious about tuning and just wanna be cool by having a laptop hooked up to your car, then EFILive is more 'graphical'.
You can order one from www.aldlcable.com or http://www.mastach.com/ or www.moates.net I wont be making them for people.

Freescan:
Now freescan gives ALOT of information to you. Among that information, some of the most important information is your BLM and INT. BLM, which stand for Block Learn Multiplier is a long term adjustment that your fueling is based on. It uses fuel tables stored on your MEMCAL's EPROM. If your O2 sensor detects your engine is running excessively rich, it will decrease the BLM which leans out the mixture. If your O2 sensor detects your engine is running excessively lean, it will increase the BLM which richens the mixture. The INT, which stands for integrator is a short-term version of the BLM. Basically if you jump on the gas, if the fuel tables dont provide correct fueling, the O2 detects this condition and rapidly adjusts. If the condition is consistent then it will set the BLM. You can also datalog, which most ECM tuners will request from you. It is a .csv (comma seperated values) table that can be imported into excel. It will log everything your engine is doing.

Hardware - MEMCAL:
Now, If you choose to proceed into tuning you will need some hardware. First you will need to replace the EPROM (electronically programmable read only memory) with an EEPROM (electronically erasable programmable read only memory). To do this, I first recommend you pick up a few spare memcals from a junkyard. It dosent matter what you get the memcal out of, as long as its from an OBD1 GM V6. so you can use MEMCAL's from an 88 corsica if thats what is available to you. since youll be removing the PROM from the memcal, you basically only need it for the socket. Once you have a few donor MEMCAL's, remove the blue cover from the memcal. There will be a chip & a board in there. The board is a noise filter for the knock sensor. you want to leave this alone. The chip seen below is the EPROM.

You want to use a fine pair of wire cutters and cut the pins off the chip and remove / disgard the chip. Then you want to get a small pair of needle nose pliers, and unsolder each pin and pull it out. Then you will need to replace the chip with the EEPROM because the stock EPROM cannot easily be erased, and its just easier to replace with a re-writable chip. These rewritable chips can be found here: http://www.mcumall.com/comersus/store/comersus_viewItem.asp?idProduct=3130
And you will need to CAREFULLY put it back into the MEMCAL socket. Take note of the way the wording is facing on the chip before putting into the MEMCAL socket.Then you will need a fine tip soldering iron, and solder each pin into the MEMCAL socket. Then you can replace the cover and your ready to go.

Hardware - PROGRAMMER:
You are going to need a programmer to write new data to your MEMCAL's EEPROM. The one I use is the Willems Dual Power Universal EPROM Programmer, found here: http://www.mcumall.com/comersus/store/comersus_viewItem.asp?idProduct=3081
Here is a picture of mine:

now, in that picture you will notice that I have made an adapter. This is because you would typically have to remove the chip from th MEMCAL to put it into the programmer to write it. Its very risky to constantly remove the chip and you can risk bending / breaking a pin. You can also buy the adapter from moates for $10 here: http://www.moates.net/product_info.php?cPath=25_36&products_id=52 Here is a picture of a MEMCAL on the programmer:

The programmer & software is very easy to use. Its basically 2 buttons. You load a .bin file, then u burn it.

Software:
Now this is where it gets interesting. First thing you want to do is put your stock MEMCAL onto the programmer and read your data off its chip. (Remember if you have a 88-90 you should be using a 91 MEMCAL.) You will want to save this file as its the file you will be tinkering with from here on in. To modify your .bin file, i recommend a program called GMPCM. Its only $30 to register and it will make your life so much easier than trying to use the freeware version. Now on the www.gmpcm.com website there is ALOT of links with good information. Please read through the links section, as well as my thread before flooding the forum with questions already been answered.

UPDATE: GMPCM has shut down, so this program is no longer available. This is unfortunate because it was an excellent program and easy to use. Other programs are on the market including: TunerCat & TunerPro. I havn't had the time to look through these programs so I am not familiar with them.

the_wagon · Posted: Mon Oct 24, 2005 12:26 pm Post subject:

That is very concise Pat. I guess I can erase my post on this topic. Thanks.

Aphytex · Posted: Mon Oct 24, 2005 12:44 pm Post subject:

Very very good post... I learned a few new things... now to get a laptop, haha

MrPaulo · Posted: Mon Oct 24, 2005 12:51 pm Post subject:

burn ur the man. It's nice to see ppl like you sharing the knowledge in a good way.

Sticky time.

SuperDave · Posted: Mon Oct 24, 2005 12:57 pm Post subject:

stuck

I'm also going to leave it here in general J since this can cover both performance and repair...

dailydriverz · Posted: Mon Oct 24, 2005 1:52 pm Post subject:

there are programs to both monitor and program 4 cyl chips. you just have to look beyond freescan and gmpcm

programs like tunercat support additional ECMS like 88-89 2.8s and 2L engines (749)

also using a 91 chip in an older ecm is like cutting your stock springs instead of buying lowering springs.

burn · Posted: Mon Oct 24, 2005 1:59 pm Post subject:

As I said, im by no means a pro at this. Ive been fortunate that I havn't had to deal with tuning a 88-90, nor with a 4cyl. These are simply the methods that I have been told of. If your tuning a 88-90, there is no reason you cant start with a 91-94 code since your going to have to make adjustments in it anyways. Obviously I dont recommend using a 91 MEMCAL in an 88-90 and leaving it like that, its meant as a starting point to simplify the tuning.

cahilj · Posted: Mon Oct 24, 2005 4:41 pm Post subject:

Very good! Very good!

scott0999 · Posted: Mon Oct 24, 2005 7:16 pm Post subject:

nice writeup! I just finished datalogging my car tonight and my chip should be reprogrammed soon

shooff · Posted: Thu Nov 03, 2005 9:36 am Post subject:

How to you build the little adapter? Looks like it's probably a good idea.

burn · Posted: Thu Nov 03, 2005 10:21 am Post subject:

scott0999 · Posted: Fri Nov 04, 2005 9:28 pm Post subject:

also using a wideband o2 sensor will give you better readings when you datalog the car

shooff · Posted: Sat Nov 05, 2005 4:41 am Post subject:

cahilj · Posted: Sat Nov 26, 2005 7:04 pm Post subject:

I did some searching around, and I can't seem to find any software that will support the 2.2 ECM. Does anyone know of any?

z-24turbo3.1 · Posted: Sat Dec 10, 2005 9:12 pm Post subject:

ok... i have no clue about all this electronics shit. i NEED help. im putting a 3.1 turbo in my 89 cavi. i got the complete harness, fuse box, ecm, ect. obviously, it is programmed for an automatic tranny. im using my 5 speed. what all is involved in reprograming it for my 5speed? also, ive heard that the tgp ecm shuts the fuel off if the boost reaches over 9.5psi. how can i clear this?? any comments about the swap in general are welcome.

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