Acceleration Enrichment¶
A transient squirt of fuel when the throttle is opened quickly, filling the brief lean dip caused by wall-wetting lag.
What it is¶
When you snap the throttle open, manifold pressure (MAP) rises faster than fuel can follow — some of the new fuel condenses on the suddenly-wetted intake walls, leaving the cylinder momentarily lean. Acceleration enrichment (AE) detects the fast pressure rise and adds a short burst of extra fuel to fill that dip. It's the simulator's version of an accelerator pump.
In Engone, AE is shaped by several tunables:
- A MAP rate-of-change dead zone (around 5 kPa/s) below which nothing triggers — so steady driving doesn't enrich.
- An addition curve — how much extra fuel for a given rate of change.
- A duration curve — how long the squirt lasts.
- An ECT scale — colder engines need more (up to about 4× when cold), because wall-wetting is worse cold.
Why it matters¶
Without AE, every fast throttle opening produces a brief lean stumble — a flat spot or hesitation right when you ask for power. Properly tuned, the tip-in is crisp and the mixture stays on target through the transient.
- Too little → a hesitation or stumble on throttle tip-in.
- Too much → a rich "blubber" and a puff of black smoke on tip-in.
How to tune it¶
Tune with quick throttle stabs and watch measured lambda. If it dips lean on tip-in, raise the addition; if it spikes rich, lower it. Use the dead zone so gentle driving is left alone, and verify the cold scale by repeating the test on a cold engine.
Rule of thumb
Tune AE warm first to get the shape right, then confirm the cold multiplier on a cold engine — cold tip-in needs far more fuel than warm.
In the game¶
AE settings are on the Fuel page. The live AE multiplier flashes up on each fast throttle opening, then returns to 1.0×.