Closed Loop Idle Target RPMs & PID tune

Hey !

Closed Loop Idle Target RPMs
Closed Loop Idle Target RPMs is where you setup your CLT to RPM curve.

This is my curve, 1600rpm when cold, down to 900rpm when hot.

Every time you start your engine after you set up this curve, pay attention to the rpm, and adjust the curve to your liking.


Closed Loop Idle PID Gains tune

From: MSEXTRA Manual

• Proportional Gain This setting controls the Proportional Gain of the PID algorithm. Setting this higher will result in a larger immediate response to changes in RPM. Setting this too high can result in unwanted oscillation of RPM.
• Integral Gain This setting controls the Integral Gain of the PID algorithm. This is the PID setting used to actually make the RPM meet the target RPM. Setting it too low will cause the RPM to never reach the target. Setting this value too high will result in unwanted oscillation of RPM.
• Derivative Gain This setting controls the Derivative Gain of the PID algorithm. It can be used to help dampen the effects of the Proportional and Integral settings. It is usually not necessary for good control of Idle speed. It is recommended that this is left at 0%.

PID Tune

1. Zero all the gains - Set all the gains to 0%. This is so that the effects of tuning the I-term in the next step are not confused with the effects of any other setting.
2. Tune the Integral (I) gain - The Integral gain is the only term that controls whether the code actually reaches its target. Higher values for Integral gain will result in the code being able to get closer to the commanded target; however, a value that is too high will result in oscillation. The easiest way to determine a good value for the I term is to keep increasing it until oscillation occurs, then slightly lower it. If this value is increased to 200% without reaching a point where oscillation occurs, then the RPM with valve opened setting can be decreased as far as necessary, and the open duty/steps setting and closed duty/steps setting can be made further apart to make the PID loop more sensitive.
3. Tune the Proportional (P) gain - After tuning the I gain so that the RPM reaches the commanded target without oscillation, the P gain can be tuned. The best way to tune this is to set it as high as possible without getting any oscillation. After setting this, try turning on the air conditioning or other accessories that normally lower RPM or increase load. When these accessories are turned on, the RPM should dip a bit then recover (the valve position should increase significantly). Using longer PID ramp to target times can also make it so that when the PID algorithm engages, a higher P gain can be set without causing oscillation.
4. Tune the Derivative (D) gain - For most users, use of the D gain should not be necessary. It substantially dampens the response of the loop.