You already know how ECU remapping can improve your car’s performance – more power and torque, smoother handling, better fuel economy. Now all you have to do is find someone to do the job. You will probably notice that some companies advertise custom or custom maps and other companies talk about using library maps. It is very important to know the difference between the two types of reassignment. Custom remapping can be more expensive, but it has significant benefits that make it worth the cost.

Bespoke or custom remapping starts with the file that is in your car’s ECU right now. The technician downloads the original car ECU map, and then modifies parts to improve engine performance. The files for many different processes are adjusted with expensive computer programs. The technician must understand the best way to recalibrate each setting; in other words, you must know what you are doing.

In addition to maps that monitor fuel combustion, the ECU also contains data relevant to your vehicle, such as immobilizer information, software updates, manufacturer’s bug fixes, etc. For this reason, only files that need to be changed are touched during remapping; other vital data about the car is left intact. Then the map returns to the ECU, overwriting the existing file. The service provider keeps a copy of the original ECU file, just in case. Custom remapping is always tailored to your particular vehicle, ensuring the best possible results.

Reassignment with a library file is quite different. The technician does not use your car’s original ECU file. Instead, a modified ECU map is chosen from a library of perhaps 10,000 generic files. The library file is copied back to the car’s ECU, overwriting everything, including vehicle-specific information that might have been in the original file.

Now this collection of library files has a murky past. It consists of ECU files that someone compiled from unknown sources, copied to a CD, and sold for a few pounds over the internet. Many, if not most, of the ECU files were stolen from professional remailers. As a result, you don’t really know anything about the quality of the files or how they might affect your engine.

Remapping the ECU with a library file is a mistake that can have dire consequences. The library file probably does not contain the immobilizer software that keeps your vehicle safe. You will not have recent software updates or crucial bug fixes. And let’s not forget that a service provider that uses library files probably takes shortcuts in other ways, with cheap tools and minimal technical training.

What happens when you replace a vehicle’s unique ECU map with a library file? Certainly the motor could generate more power after reassignment, but there is no guarantee that the improvement will be as expected. Your engine system can suddenly develop faults and not function as it should. The ECU could freeze up and become inaccessible so you can’t even repair the damage. Without normal security features, your car could be more easily stolen. And worst of all, you may be forced to spend a lot of money replacing the ECU or repairing the engine.

Now that you know why custom maps are so much better than library maps, how do you find someone to do the job? First of all, make sure that the company actually offers a custom reassignment done by qualified technicians. It is not difficult to know if you are dealing with a professional or an imposter. Ask the technician some questions about how remapping is done, what kind of files it uses, what engine settings are changed, etc. A qualified and experienced person will be able to perfectly explain the finer points of the reassignment process. And if someone mentions library files or tries to convince you that library files are only as good as custom files, cross them off the list.

There is nothing wrong with shopping to compare prices, but don’t make price the deciding factor. This is a high-tech industry, and technology costs money. If you find a service provider with very low prices, ask yourself why. In all likelihood, they are using cheap library files and tools to remap.

You should also reassure yourself about the after-sales support of the company. Is there a trial period after reassignment? Do you keep a copy of the original map in case you ever want to change it again? Does the labor come with a warranty? Does the company guarantee improvements in BHP, torque and fuel economy? Make sure you are satisfied with the answers to these questions.

Remapping the ECU is an effective way to increase engine performance, but if not done correctly, you really put your car at risk. There is no question that custom or custom remapping is a better option than remapping with library files. You will get the best results and, just as important, you will protect your expensive vehicle from damage.