There are now a multitude of companies that will remap the ECU on your vehicle. In most cases, this entails plugging a computer into the diagnostics port on your vehicle that directly communicates with the ECU. A technician reads the existing file on the ECU and overrides it with a new file. The new file has on it adjusted parameters which alter a number of characteristics on the engine. These include the amount of turbo boost pressure (if applicable), the fueling and ignition timing (if on a gasoline vehicle), and other such parameters.
What can happen on a diesel engine after remapping is that the amount of smoke coming out the exhaust increases, particularly on heavy acceleration. Where you once had a small amount of smoke from your exhaust, you now have a problem with a heavy amount of smoke. Any underlying running problems can be exacerbated with an engine remap. One of the things that surprises me tremendously is that many companies do not carry out a health check. Lots of remap servicers are mobile; they do not have the necessary tools, equipment, or expertise to precheck the vehicle. None of them, as far as I have researched, ensure that the fuel system is running correctly and that there isn’t an excess of carbon buildup.
If you are pushing the engine by asking it to work harder and produce more power, it is essential that you ensure that you have the best platform from which to remap and gain that additional performance. To guarantee this, the first thing we advise is to carry out a health check. Make sure there are no error codes. Then combine the remap with a professional fuel system cleaner and carbon remover. It is essential that the fuel system is running efficiently before you remap your vehicle. On a petrol engine, it is essential that the ignition components, the ignition system, and the fuel system are performing optimally in order to maximize the benefits to be gained from a remap.
Wherever you go to have your vehicle remapped or chipped, make sure the service includes the necessary checks. Also make sure you use a high-quality fuel system cleaner, particularly if your exhaust has any excess smoke. If you have excess smoke, I strongly advise that you get the issue resolved or checked before performing a remap.