7.6 Boost / VVT 7 ADDITIONAL ITEMS: BEYOND BASIC FUEL AND IGNITION CONTROL
• Boost Control Lower CLT Threshold - To prevent running maximum boost before the engine is warmed up,
the MS3Pro will run minimum boost until you reach this temperature, at which point the boost control turns
on.
• Algorithm - If using single solenoid mode, open loop
7.6.2.2 Closed loop specific settings Enabling the closed-loop boost control algorithm enables the following
additional settings:
• Boost control use initial value table - If this is set to On, the boost control will start with an initial duty cycle
table whenever it moves into a new load cell as a feed-forward mechanism. If it is set to off, the boost control
will adjust from the previous duty cycle it was running at, and operate purely from the feedback loop.
• Boost Control Lower Limit Delta - This regulates how close the boost must be to your target to engage
closed loop control. When the boost is more than this amount below your target, the controller holds the
valve wide open to maximize spool up speed.
• Tuning Mode:
– Setup Mode - PID correction is turned off to allow adjusting the bias tables. Set the bias tables so you
reach your boost target levels.
– Basic Mode - The PID parameters are all set to 100%, and you only tune with the slider.
– Advanced Mode - All PID parameters are adjustable.
• Closed Loop Sensitivity - Use this setting to tune how aggressively the boost controller tries to reach the
target boost. Adjust the slider up until the boost oscillates around the target, then back down until it stops.
• Proportional Gain - Proportional gain affects the strength with which changes in input immediately affect
changes in output.
• Integral Gain - The Integral Gain setting affects the response to continued difference between the target
boost and the actual boost.
• Derivative Gain - The Derivative Gain setting helps to slow down the response of the Proportional and
Integral gain settings as the target is reached. This should be used sparingly as it can also completely
dampen the other two Gains.
The first step for tuning Closed-loop boost control is to set the desired targets in the Boost Control Target table
(section 7.6.3). Typically, lower throttle positions will have lower boost targets. This lets you modulate the boost
with the throttle.
Once you have set the targets, set the tuning mode to Setup Mode. Then adjust the boost control duty bias
table so that you hit your boost targets with the duty cycles used in this table.
Typically, the defaults for the following settings can be used:
• Closed Duty - A closed duty of 0% is the default. This should be tuned to the value that starts to open the
wastegate, but typically 0% works well.
• Open Duty - An open duty value of 100% is the default. This should be tuned to the value that fully opens
the wastegate, but typically 100% works well.
• Boost Control Lower Limit - This setting is used to set the pressure at which PID boost control is engaged.
The default for this setting is 100. If a faster rise to target is desired, this setting can be set to a higher
number, but the safest number is 100 since it gives the PID code the most time to react to climbing boost.
The next step after setting up the target table and supporting settings is to adjust the slider for best performance. If
the slider on its own does not give the results you hope for, you can go to advanced mode and tune the PID gains:
1. Set Integral and Differential Gains to 0% - This will let you focus on tuning the proportional gain.
AMP EFI MS3Pro manual version 1.202, firmware 1.5.0, 4/21/2017 Page 203
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