To turn on O2 control in the Haltech NSP tuning software navigate to the “Fuel Tuning” section and turn on the “O2 Control” function checkbox. You can also navigate to all the tuning functions by pressing the F4 button and turn on O2 control from here.
In the O2 Function Setup page, we have the control parameters that the O2 control is going to work under, most of these are easily understood. Things like Initial Engine Run Time, Minimum Coolant Temp, and Minimum and Maximum RPM settings don’t need any explanation.
We will concentrate on the 4 settings that we get the most questions. The dropdown box allows you to select which sensor you are going to use for O2 control. 9 times out of 10 this will be the only sensor you have so it’s a simple decision. However, there are times where you may have more than 1 O2 sensor in which case you would select the configuration of O2 sensor that matches your engine.
In our example, the engine is a straight-six, but since it’s got two exhaust manifolds and two 02 sensors we will assign a Wideband to each bank.
The next setting in the software is the “STFT Enrichment” and “STFT Disenrichment”. This is where we need to understand how the O2 control system works in a broad sense.
Short Term Fuel Trim can be thought of as an instantaneous adjustment because the O2 sensor looks at the actual air-fuel ratio, compares that to the target air-fuel ratio if they are different an immediate correction is made.
However this Short Term Fuel Trim is just that – short-term. It does not get stored or saved anywhere, so no ‘learning’ is ever applied. For the ECU to learn and save this information we need to go down to the Long Term Fuel Trim settings which we’ll get to shortly. First, we need to clarify the least understood setting in the Short Term Fuel Trim function and that is the Target Oscillation Amplitude.