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Cranking Enrichment

Extra fuel added only while the starter is turning, scaled by temperature — the most basic cold-start aid.

Demo build: this panel is locked

The enrichment column is available in the full game. See Demo vs Full Version.

What it is

While you hold the starter (R), the engine isn't running on its own and the normal fuel logic doesn't apply cleanly. Cranking enrichment is a multiplier of extra fuel for those few seconds, sized by coolant temperature. The grid accepts 0.5–5.0×.

The classic curve (used when wall-film compensation is off) runs from 3.5× at −40 °C down to 1.0× at 80 °C:

Coolant (°C) −40 −20 0 20 40 60 80
Multiplier 3.5 3.0 2.5 2.0 1.5 1.2 1.0

The stock tunes ship with wall-film compensation on. There the ECU models the fuel puddle itself, and the cranking table is only the cranking mixture — about 1.03–1.10×.

Active window. With wall-film compensation off, cranking enrichment applies while cranking and RPM is below about 550. With it on, it applies until the engine catches.

Why it matters

A cold engine suffers badly from wall-wetting and poor atomization (see Enrichment Overview), so it needs far more fuel commanded just to get a combustible mixture into the cylinder.

  • Too little cranking fuel → the engine won't catch when cold (a frustrating no-start).
  • Too much → flooding. Running far too rich (λ below about 0.65) at low RPM wets the plugs, the state window shows FLOODED, and the engine won't fire until it clears.

Clearing a flood. Hold the throttle above 75 % while cranking: fuel is cut to ×0.05 until the plugs dry. Release the throttle once it clears.

How to tune it

Adjust the cold end of the curve if cold starts are unreliable. Raise it if a cold engine cranks but won't catch; lower it if it floods (catches, stumbles, and dies in a cloud of fuel).

Rule of thumb

Tune the coldest cells against the coldest start you expect. The warm end should sit near 1.0× — a hot engine barely needs cranking enrichment at all.

Watch out

Flooding from over-rich cranking looks like a fuel-starvation no-start but isn't. If it fires briefly then drowns, reduce cranking fuel, not increase it.

In the game

FUEL page → right column → CRANK ENRICHMENT card. It shows ECT: … (the coolant temperature) and the live multiplier, plus the chip ACTIVE / INACTIVE (or FLOODED / CLEAR FLOOD). The COOLANT bar in the TEMP box tells you which part of the curve is active for the current start.