Lambda Target Table¶
The map of desired lambda across RPM and load. Fuelling and closed-loop trim aim at these numbers.
What it is¶
The lambda target table is a grid of RPM × MAP / load cells, each holding the lambda you want the engine to run at that operating point. It is the goal, not a measurement — the speed-density fuel calculation aims for it, and closed-loop trim fine-tunes toward it.
Why it matters¶
This single table sets the character of the tune: economy, power, and safety all come from where you place these numbers. A sensible petrol map looks roughly like:
| Region | Load | Target λ |
|---|---|---|
| Light cruise | < 30% | lean (> 1.0) |
| Mid load | 30–70% | stoich (≈ 1.0) |
| Wide-open throttle | high | rich (≈ 0.87) |
Cold operation pulls the effective mixture richer still, layered on top by the enrichment stack.
How to tune it¶
Set lean targets only where the engine is lightly loaded and cool enough to tolerate it; bring targets to stoich through the mid-range; and richen toward λ ≈ 0.87 as load and RPM climb so the charge stays cool and knock margin stays healthy.
Rule of thumb
Build the table in bands: a lean cruise plateau, a stoich shelf, and a rich WOT ridge. Smooth transitions between them prevent surging as load changes.
Watch out
Lean targets at high load are dangerous. If in doubt, target richer — fuel is cheaper than pistons.
In the game¶
Open the Lambda page. The active cell tracks the engine; the live lambda gauge shows how close measured λ is to the target you set.