When, why and how should I tune the ECU?

Easy tuning
is used when the before mentioned lean-burn is present in original engines or with minimal tuning such as a high flow air filter or the snorkel of the Kawasaki KDX. The tuning box is installed between the ECU and the wiring harness goes to the injector and changes the values sent to the ECU so that they are as close as possible to the optimum air/fuel ratio. With this system it is usually not possible to influence the actual condition. The result is a smoother running and improved throttle response. Even with this system there is a wide range of suppliers offering different control solutions. 

The situation is a little different
if you have already provided more air flow on the intake side and installed a performance-enhancing manifold and silencer you have to influence the amount of fuel needed to fill the combustion chamber. This is done in a similar way to tuning a carburetor, where the nozzles and needle are adapted to the engine.

With EFI - electronic fuel injection - this is done by an additional control unit or by replacing the original ECU, where the amount of fuel can be adjusted to individual areas of the throttle position. Often these control units are offered pre-programmed for the respective model. The final touch can then be made by adjusting the fuel injection quantity on the additional control unit as required, nowadays even by smartphone via bluetooth.

With a little experience you will get very useful results and the engine should have a noticeable increase in power over a large part of the rev range. Unfortunately the ignition curve cannot be influenced with this tuning variant.

If you have a test bench available the adjustment process can be carried out even better and the nice thing is that you also have a characteristic curve with engine power and torque. The advantage of these systems is that if changing the engine setup,i.e. install a different aftermarket exhaust, I can easily adjust the ECU by the setting knobs. Self-learning systems are used here as well.

When the engine is tuned even further
than described - a big bore kit is installed, other camshafts and valves, perhaps even the stroke of the crankshaft is increased or a larger throttle body with a more powerful injector, the only thing that helps here is a new freely programmable ECU. However, this requires a lot of knowledge and experience in programming such a box.

A big advantage of these systems is that not only the fuel injection quantity can be changed, but also the ignition timing. And to make things even more complicated, this can be done in very small steps - i.e. speeds from idle to rev limiter and for each gear individually.

Even for the cold start phase, a separate map can be created. With this type of ECU tuning a dyno is an absolute prerequisite.

Sensors on the KLX 250 which affect the mixture preparation
- Main Throttle Sensor
- Sub Throttle Sensor
- Speed Sensor
- Crankshaft Sensor
- Inlet Airpressure Sensor
- Inlet Airtemperature Sensor
- Water Temperature Sensor
- Oxygen Sensor


Companies/brands
Dyno Jet
API TECH
Dobeck Perfomance
Dynatek
Bazzaz
Booster Plug
Jetprime
Rapid bike