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Fuel

How Engone decides how much fuel to inject, and when.

The ECU's tables decide how much fuel is injected. How much air the engine actually breathes is decided by the parts you built — editing the VE table changes the ECU's belief, never the airflow.

Fuelling at a glance

The ECU meters fuel in a chain you can follow cell by cell:

  1. Estimate air mass. Using speed-density, the ECU combines the MAP sensor, the VE table, and air temperature to work out how much air actually entered the cylinder this cycle.
  2. Pick a target. It looks up the desired mixture from the lambda target table — leaner for cruise, richer for full load.
  3. Compute the pulse. Given the air mass, the target lambda, and the injector flow at the current fuel pressure, it calculates the injector pulse width.
  4. Add enrichment. Cold starts and fast transients need more fuel than the base calculation — the enrichment stack layers that on, and wall-film compensation models the fuel puddle on the port walls.
  5. Trim to target. When conditions allow, closed-loop fuel trim reads the exhaust O2/lambda sensor and nudges fuelling toward the target.

Petrol

A petrol engine throttles air and aims for a specific air–fuel ratio (usually near stoichiometric, richer at full load), with the spark timing the burn. Engone currently simulates petrol (spark-ignition) engines.

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Cold idle is a fuel-adjacent setting but lives with the idle controller — see Cold Idle.