After-Start Enrichment¶
A decaying dose of extra fuel for about a minute after the engine catches, to cover wall-wetting before the intake warms.
Demo build: this panel is locked
The enrichment column is available in the full game. See Demo vs Full Version.
What it is¶
The moment the engine starts running on its own, cranking enrichment ends — but the intake is still cold and wet. After-start enrichment bridges that gap: it adds a percentage of extra fuel that decays over roughly 60 seconds to zero.
Two things shape it:
- Initial amount — set by coolant temperature (ECT) at the moment of start; colder starts begin with more. The initial value is latched at the moment the engine catches.
- Decay — time-based; the extra fuel tapers smoothly as the seconds pass and the intake warms.
The default curves:
| Coolant (°C) | −40 | −20 | 0 | 20 | 40 | 60 | 80 and above |
|---|---|---|---|---|---|---|---|
| Initial amount | 80 % | 70 % | 40 % | 15 % | 8 % | 3 % | 0 % |
| Time since catch (s) | 0 | 5 | 15 | 30 | 45 | 60 |
|---|---|---|---|---|---|---|
| Share of the initial amount left | 100 % | 85 % | 50 % | 20 % | 5 % | 0 % |
Like warmup enrichment, it tapers with load.
Why it matters¶
Right after start, a lot of commanded fuel still condenses on cold intake walls (wall-wetting) rather than reaching the cylinder. Without this layer the engine would lean out and stumble in the first several seconds of running — exactly when it's most fragile.
- Too little → the engine sags or nearly stalls just after catching.
- Too much → it runs over-rich and rough for the first minute, possibly fouling.
How to tune it¶
Tune by feel in the first minute after a cold start. If the engine catches cleanly then stumbles a few seconds later, raise the initial amount. If it catches and runs rich/rough before smoothing out, lower it.
Rule of thumb
Cranking gets it to fire; after-start keeps it alive until warmup enrichment takes over. Tune them in that order: catch first, then stabilize the first minute.
In the game¶
FUEL page → right column → AFTER-START ENRICHMENT card. It has two curves — ECT → INITIAL and
TIME → DECAY — and live TIME and multiplier readouts. The multiplier visibly decays toward 1.0×
over the first minute; watch it alongside the COOLANT bar.