What this table does
The Open Loop Base Duty table is only used when Boost Control Mode is set to Open Loop. It holds the solenoid duty the ECU will output, and nothing else changes it. There's no boost target, and the ECU doesn't correct toward one. Whatever duty you enter is the duty you get, so you adjust the cells until boost lands where you want.
The table supports up to 4D mapping, so duty can depend on more than one channel, not just rpm.
How we tune it
- Start with low duty so boost sits near wastegate spring pressure.
- Raise duty in small steps, logging boost each pull, until you reach the level you want.
- Shape the table across rpm, since most turbos need less duty to hold boost as they come fully alive.
Open loop is predictable and easy to diagnose, but boost will drift as weather and air temperature change. That's why we usually tune here first, then copy the duties into the closed loop base duty table as its starting point. For the trade-offs, read closed vs open loop boost control.
With no target, nothing pulls boost back if a hose splits or conditions change. Always set up an overboost cut.
