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Single Turbo RX7 - Haltech with 3 port MAC valve - boost oscillating

Boost Control

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I have a single turbo RX7 with a efr 8374, dual tial mv-s wastegates, a 3 port mac valve, and a Haltech 1500.

I am having an issue running anything above wastegate spring pressure. The boost will oscillate uncontrollably under full throttle until it hits my boost cut at 20 psi. If I set all of my values to zero the car is fine and there is no oscillation.

I have included a graph and my settings.

Attached Files

Have you tried values between your current values and zero? What happens if you turn on closed loop and allow the control system to do it's job?

MAC valves are usually pretty inconsistent when aiming for duties under 20%. Also having a big step in your table going from 50% to 15-19% can cause those oscillations.

Are you planning on keeping the system in open loop, or switch over to closed loop once you dial in the base duty. Id recommend setting a boost liming, and putting in a 20% duty in the table up to your aim boost as a starting point, to see how the boost behaves, and then review the changes in boost and adjust from there. Changes of 3-5% duty can add 10kpa in some applications, so be mindful of this making further adjustments.

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