I understand that the long term fuel trim figure LF1, readable from the OBD2, indicates how much more or less fuel is being injected over the default mapping.
Note that LF1 is a 2D or 3D map of rpm, load, temperature- maybe more parameters?
My understanding is that it ultimately is measured with respect to the O2 sensor.
A negative figure means that the O2 sensor measures rich on the default map, so less fuel is put in relative to the default map. A positive LF1 means a lean measurement at the O2 sensor, so more fuel is added over the default map.
I'm interested to know what figures my fellow 1ZZ-FE users are finding.
It's important to record the LF1 reading under the same test conditions. Idle, no throttle being the most obvious. Also with a fully learnt map (i.e. car has been driven 500 miles since an ECU reset).
At idle my own LF1 reads -6.
This can be read by an Xgauge scangauge:-
https://www.scangauge.com/xgauge/fuel-trim-canlf-5/
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