How to Remap

We’ll show you how to remap.

Can I remap my car? Can I remap my ECU myself? The short answer is yes. The long answer is – yes, but it’s complicated.

Graph of fuel injection quantitySo you want to learn how to remap? Well it’s not easy. We only know a fraction of what is neccessary to remap a car, or how to remap a car on your own, but we’ll share what we do know. We spent a lot of time reading and researching before buying our first remap tool and plugging it into a car. I’m not a big risk taker, so I did things carefully. Some people are happy to just download a free remap from bit torrent and put on their car. The thought of doing that sort of DIY remap makes my brain hurt.

The basics

Engine gears, bolts, and spark plugsEngines mix fuel and air. It burns (combusts) inside the engine explosively. Through lots of mechanical parts this causes a driving force against the wheels and makes them spin. Those mechanical parts are pistons, connecting rods, clutch, gearbox, driveshafts, and more.

The fuel/air mixture is vital. Too much fuel and the combustion won’t be explosive enough or it won’t ignite at all. Too much air and the mixture will go off like a miniature bomb, resulting in bent engine parts and sadness.

A map is a set of instructions programmed onto the car’s ECU by the manufacturer to handle the fuel air mixture and hundreds of other parameters. A remap is changing the manufacturer’s engine “map” to a custom setup of your own.

For example the manufacturer map may include a fuel quality adjustment for safety purposes. If low quality fuel is present the ECU can adjust the mixture of fuel and air to prevent engine damage. If I always run my car on specialised race fuel I don’t need that fuel quality restriction, so I can keep the ECU on maximum power instead of having the safety feature. Power is good. Power is what you need.

The risks

  1. Vehicle engine warning lightYou can seriously f**k up your car.
  2. Your remap could do irreversable damage to the engine.
  3. You could disable your immobiliser features and your key will no longer work.
  4. You will almost certainly invalidate your warranty. Vehicle manufacturers do not want you to mess with their ECU software.
  5. Did we mention you can seriously f**k up your car?

The benefits

  1. Audi A6 Quattro dyno dynamics remapYou can gain more power from the engine than the manufacturer intended.
  2. You can choose to enable or disable features e.g. Launch control, automatic gearbox shift points, traction control, DPF, EGR.
  3. You can sometimes improve fuel efficiency.

Cables

how to remap cableOfficial and genuine cables are expensive but more reliable and better supported. There are excellent flash and read tools such as Amtech MPPS, Alientech KESS/K-TAG, Dimsport Genius, and FGTech Galletto.

There are clone tools available from ebay or independant websites. These may be illegal if they violate intellectual property, and they also may be unreliable. They may be a good way to learn without spending a lot of money if you’re happy taking on the risk of the remap going wrong.

Software

remap binary dataThe ECU map is stored in digital format on the memory of the ECU. A remap must change the contents, but since none of us speak the binary language of computers we need some software or an application to translate for us. Software packages like WinOLS and ECM Titanium provide this and you can also find free remapping software such as VAGsuite.

Checksums

how to remap checksum iconManufacturers use a checksum process to make sure the ECU map has not been tampered with. It’s a mathematical check to make sure the map is not corrupt.

To illustrate we could imagine a tuned remap file and sum up all the 1 and 0 bits in the binary file. For example if a normal file has exactly one million 1s present the car can check the current remap to see if it also has one million 1s. If it does not, there is an error and the car may not start.

Tuning software with checksum checking can “pad” the file with the neccesary bits so that it passes the checksum test. It could move to a meaningless part of the ECU map and add enough 1s to pass the checksum verification.

In reality the process is more complex, but hopefully this helps to explain.

More

We have a series of how to remap videos on YouTube.

We’ll be adding more content and articles in the next few weeks.