Due to the large number of enquiries I've had about Chip Tuning using KWP2000+ and SPI Interfaces, I've decided to set up this info page to explain the basics.
In the past Chip tuning was performed by physically changing a chip in the ECU of the target vehicle. In the modern vehicle chip tuning refers to the following 3 steps:
1. Downloading the information from the vehicle's ECU
2. Modifying the ECU file
3. Loading the modified file into the ECU to achieve the desired performance enhancements
The KWP and SPI units perform steps 1 and 3 of the process, namely downloading the original ECU file and uploading the modified file. The most important and complicated part of the process is however step 2 .
There are 3 ways to perform step 2 (maybe more).
The first is to buy an already modified file off the internet. This is great if you can verify the contents of the file and are sure that it contains the modifications that you require.
The next solution is to send the file to a “Tuning” company that will modify the ECU file to your requirement and return the modified file to you for you to upload to the car. Of course there is a cost attached to have this done.
The third solution, and the route that most people would like to take, is to modify the file themselves. This seems like a simple solution, but is not as easy as one might first think, as they say, if it were that easy everyone would be doing it!
The Process
The process of modifying an ECU file starts with finding a program that can read and modify the ECU file. The ‘industry standard’ is WinOLS , but actually any HEX editor like WinHEX for example will also work.
So you use your HEX editor to open up your downloaded ECU file and now you are faced with a bunch of HEX code. Hidden Within the HEX code are groups or sections of code (which we call MAPS) that contain the specific information we would like to edit. A map could for example contain the information for load vs ignition adv vs rpm or airflow vs fueling vs rpm. Luckily for us the writers of WinOLS have created a program that searches for and finds “potential maps” within the ECU code. The issue is that you cannot tell offhand which of these ‘potential maps’ contain which information. Of course the map information varies from car to car, actually from model to model. So it becomes a process of trial and error, to modify part of the code, and check what impact it has on the performance of the vehicle. With experience, one would learn which part of the code represent what parameter and thus what to modify. Of course there are people out there who already have this information, but you can see why they guard it so closely!
More Details
For those of you brave enough to want to continue, Here are more details. I believe the present cost of WinOLS is about 4000 Euro . There is a Demo version available , but it doesn’t allow you to save your mods, but it does allow you to view and mod files that you download. The simple way around this is to prepare your mod file in WinOLS Demo, record all the changes, and then mod the file using another HEX editor like WinHEX. Slightly longer process, but totally free!!
The other issue is checksums. Checksums are basically used to check whether a file has been transferred without errors. This is one of the first things that a car’s ECU checks. If you change part of the ECU code, in theory the checksum will change and the ECU will register an error. If a file with an incorrect checksum is loaded into the ECU, the results could vary from a simple error message (Diagnostic trouble code : ECU Checksum error) to complete irreparable ECU failure.
Of course WinOLS has the facility to correct checksums (of course you pay per checksum DLL that they supply, so you have to buy one for each ECU you mod). There is a way around this as well as there are stand alone checksum checkers like “ Express checksum calculator “ which you can use to check the checksum on you original file and match it to your modified file. Checksums are basically a sum of all the values within a file, so you can change the file and then correct the checksum by “balancing” the values by modifying some other part of the code . In simple numbers terms : original file 2+3+5+0+0+0 =check sum : 10 ; modified file 3+4+6-1-1-1= check sum : 10
The Verdict
So there you have it ! These are the basics of chip tuning as I understand them. It’s a lot of work to do it from scratch, but if you do it right, you can be confident that the car you mod will behave as you want it to, and with that will come the satisfied customers and the profits that come with that.
PLEASE NOTE
THE INFORMATION PROVIDED IS PROVIDED IN GOOD FAITH AS A VERY BASIC GUIDE AND IS BELIEVED TO BE CORRECT.THE ECU FLASHING TOOLS ARE USED ENTIRELY AT YOUR OWN RISK. WE ACCEPT NO RESPONSIBILITY FOR ANY CONSEQUENCES RESULTING FROM USING THIS EQUIPMENT. PLEASE RESEARCH AND FIND OUT AS MUCH AS YOU CAN ABOUT CHIP TUNING BEFORE ATTEMPTING TO TUNE A CAR