All Adaptronic ECUs offer closed loop fuel tuning, and all but the e420d also offer adaptive fuel tuning.
Closed loop fuel tuning is where the ECU has a target air fuel ratio or lambda which it is trying to achieve. The ECU compares the output of a lambda sensor with the target lambda and adjusts the injector duration to try to achieve the target. This is accomplished using a trim percentage that is applied when the injection time is calculated, rather than by adjusting the fuel map itself.
Adaptive fuel tuning is one step more developed and actually takes this trim percentage and applies this value to the numbers in the fuel map. Some people call this “Autotune” but this is a trademark of Autronic so we don’t call it that.
I’ll start of by explaining closed loop tuning first of all, since you need to understand that to be able to set up adaptive fuel tuning.
To set it up:
oxygen sensor, then the ECU will only be able to run closed loop around a
narrow range around lambda 1 (or AFR 14.7 for petrol / gasolene).
Otherwise, using a wideband sensor, the ECU can go closed loop over the
range of the sensor
the ECU goes into closed loop fuel control, for example minimum
temperature maximum engine speed, maximum MAP and so on. The ECU will also
go open loop if the target AFR is outside the range of the sensor.
will go to black rather than red in open loop mode. You can also tell
this on the ECU data window (by pressing F11).
try to reach the target AFR.
correction at 10%. If you want it to react faster then you can increase
these, but like most control loops, if you crank up the gain too much,
then it will become unstable, especially at low RPM. You want to be in a
situation where the trim is moving back and forward by 1%.
if you set this low RPM threshold to a non-zero value, then the ECU will
look at these values instead of the normal ones when the engine is below
this RPM. These gains are scaled down by a factor of 4, so 4 in here
corresponds to 1 in the normal range.
Some words of caution regarding adept tuning:
for the tuning process.
cell is a long way from where it should be, then the ECU needs to
adjust the closest cell even further in the opposite direction. If you
start off too far away from the target, you can end up with a mountain
range in your map.
expect to do a full throttle run in second gear on a car with high
acceleration and have the ECU make all the corrections because the
engine won’t stay long enough at each cell in the map.
In many cases it’s still most efficient to “rough out” the map by hand based on a few data points, eg: a few different load points at say 2000 RPM and then use the adaptive tuning function to fine tune on the dyno or the street.
