Aftermarket stand-alone ecu’s are just that – a direct replacement for the factory unit, and completely take over all control functions of the old ecu. Sometimes these units are a direct plug in replacement option, whereas other times they may require a full custom rewire of the vehicle’s engine harness. Generally, but not In all cases, these units are more powerful, faster, and provide the user with almost infinite adjustability combined with increased inputs and outputs. Sometimes the manufacturer may provide some form of ‘base map’ for the vehicle, but generally these ecu’s are completely reconfigured from head to toe.
An ecu remap on the other hand, involves us tuning the manufacturers factory ecu hardware. Different platforms do it via different methods (sometimes we must physically solder and de-solder new hardware to the pcm in order to gain access, whilst other times we can read and program directly to the pcm via specialty tuner interface devices. From here, we are actually modifying the factory mapping and parameters, rather than completely devising new ones from scratch. We assess the factory mapping, improve on the areas which we can see potential gains, and leave the other factory protocols in place.
Piggy-back ecu’s connect between your existing factory ECU and the engine sensor inputs and outputs. Different makes and models all go about their business in different ways, but the essence of the piggy back is a ‘combined’ approach between a stand alone or a remap – we can modify certain parameters that we wish or have access too, but can leave untouched the factory areas that are already optimal. It must be noted however, that as a rule of thumb, piggy-back’s quite often fall into the same trap as mentioned earlier in regards to the method in which they make their desired changes.