Open Loop
Fueling runs from a fixed map without O2 sensor feedback, typically at WOT under boost.
Why it matters
In open loop, the tune's fuel tables must be accurate because the ECU is not self-correcting. This is why tune quality matters most under WOT.
What to look for
AFR/lambda accuracy during open loop WOT reveals how well the tune is calibrated for your hardware and fuel.
Related terms
The ECU uses O2 sensor feedback to actively adjust fueling in real time.
The ratio of air to fuel in the combustion chamber. Lower number = richer (more fuel). Higher number = leaner (less fuel).
Another way to measure air-fuel ratio, expressed as a ratio where 1.0 = perfect stoichiometric combustion. Below 1.0 = rich. Above 1.0 = lean.
Want to learn more about Open Loop?
Get our free logging setup guide -- covers the channels you need, what to look for, and how to interpret your data like a pro.
See Open Loop in action
Upload your datalog and every finding, including Open Loop, will be explained in plain English with actionable next steps.
Analyze your own log