MAP — Manifold Absolute Pressure¶
The pressure in the intake manifold, in kPa. It's the primary load signal — the vertical axis of almost every table.
What it is¶
The MAP sensor reads the absolute pressure inside the intake manifold in kilopascals (kPa). At idle the throttle is nearly closed and the engine pulls a strong vacuum, so MAP is low (well below atmospheric). At wide-open throttle MAP approaches barometric. In short, MAP is a direct read of engine load.
Why it matters¶
MAP is the backbone of the speed-density approach:
- It's the load axis for the VE, lambda, and timing tables — the cell the ECU looks up depends on MAP.
- It drives the air-density term in speed-density: more pressure means more air mass.
- Its rate of change triggers acceleration enrichment — a fast MAP rise means a throttle tip-in.
A wrong MAP reading throws off fuel and spark at once, because both read from it.
How to tune it¶
MAP isn't tuned — it's an input you read. Use it to know which table cell you're in, and to confirm load is doing what you expect (low at idle, high at WOT).
Rule of thumb
When tuning a specific cell, hold the engine at the RPM and MAP that select it — otherwise you're editing a cell the engine isn't actually using.
On a boosted engine
Engone currently simulates naturally aspirated engines only. For background: a boosted engine packs far more air into the cylinder, so the tune changes — target lambda moves richer (to cool the charge and protect against knock), ignition advance comes down in the boosted cells, compression ratio is usually lowered, and higher octane matters more. See Boosted Engines (Background).
In the game¶
MAP is shown in the throttle box (MAP) and in the bottom bar of the VE, lambda and ignition pages.
It also appears as vacuum on the gauge in the right column (negative means vacuum, 0 is
atmospheric). Watch it swing low at idle and climb toward atmospheric under load. You can change the
unit under OPTIONS → GAMEPLAY → UNITS → MANIFOLD PRESSURE.