Diesel Fuelling¶
Diesels run unthrottled and control power purely by fuel quantity, limited by a smoke ceiling — and they have no spark.
What it is¶
A diesel works fundamentally differently from a petrol engine. There is no throttle: the engine always breathes a full charge of air. Power is set entirely by how much fuel is injected, and ignition comes from the heat of compression — no spark, so none of the ignition pages apply. In Engone, diesels use a dedicated ECU.
Why it matters¶
Because air is essentially unlimited, the constraints move to the fuel side:
- Smoke limit — inject too much fuel for the available air and the surplus burns incompletely as black smoke. Engone enforces an AFR floor of roughly 18:1 to keep combustion clean. This is the diesel equivalent of a rich limit.
- Cold warmup — cold diesels need heavy enrichment to ignite reliably (up to about 2.5× at −40 °C).
- Common-rail pressure — there's a minimum rail pressure (around 150 bar) below which fuel won't atomize or ignite properly. See Fuel Pressure.
How to tune it¶
Tune the fuel-quantity demand against load, keeping the mixture above the smoke-limit AFR floor at full fuelling. Make sure cold enrichment is sufficient for reliable cold starts, and that rail pressure stays above the atomization minimum across the rev range.
Rule of thumb
On a diesel, "more power" means "more fuel until the smoke limit" — not more air. If it smokes black under load, you're past the AFR floor; back the fuel off.
Watch out
Low common-rail pressure on a diesel isn't just a lean condition — below the minimum the fuel won't ignite cleanly at all. Treat rail pressure as a hard prerequisite.
In the game¶
Diesel builds select the diesel ECU automatically (set by fuel type in Engine Setup → Engine Base). The Fuel page shows fuel quantity, the smoke-limit AFR, and rail pressure rather than a spark table.