How the enrich tables work together
The final extra fuel for a throttle event comes from multiplying two things: how much enrichment the Amount table allows, and what share of it the Rate table says this particular throttle movement deserves. A gentle roll-on gets a small slice; a hard stab from closed throttle gets much more.
Enrich Rate
This is the proportioning table, and the one people most often mistake for the amount. Its X axis is how fast the throttle is moving, and its Y axis is where the throttle was when the movement began. That second axis matters: snapping open from idle needs far more help than the same speed of movement starting at half throttle, where airflow is already high. It can be mapped in up to 3D.
Enrich Amount (Sync)
Synchronous enrichment makes the normal, in-time injector pulses longer. It's the efficient way to deliver transient fuel and where tuning should begin. The numbers read like VE: they aren't true volumetric efficiency, but bigger values add more fuel and smaller values add less. It's usually mapped against RPM, with up to 3D available.
As a guide, expect values somewhere around 25 to 50 at low RPM and 100 to 200 at high RPM. Use those to sanity-check a starting map, then tune from logs rather than treating them as targets.
Enrich Amount (Async)
Asynchronous enrichment fires extra injector pulses in between the normal ones, so fuel arrives immediately instead of waiting for the next scheduled pulse. Tune it after the sync table is sorted. It earns its place when:
- the injectors sit a long way from the intake valves, as on some throttle-body or upstream setups,
- big ports or weak part-throttle airflow let fuel fall out of suspension (a little helps here), or
- the engine is a rotary, where async enrichment is common practice.
It uses the same VE-style scale as the sync table, typically against RPM, up to 3D.
Ign Corr
Ignition can be adjusted during a transient too. Positive values advance, negative values retard, and the correction fades out over the Ign Corr Decay Time. A little retard can calm a lean hesitation or surge while the fuel catches up; a little advance can sharpen response. Up to 3D mapping is available.
Our tuning order
- Get steady-state fueling right first. Transient tables can't fix a bad base map.
- Shape the Rate table so small movements get little and big stabs get a lot.
- Tune the sync Amount against RPM until the wideband stays steady on tip-in.
- Add async only where the sync table can't keep up.
- Use ignition correction last, for polish.
Related pages: the transient throttle overview, disenrich for throttle closing, coolant temp correction for cold engines, and our explainer on transient throttle as an accelerator pump.
