Update Idle-Tuning.md

docs/Basic-Features/Idle Control/Idle-Tuning.md

@@ -22,16 +22,15 @@ Within the idle settings, the first set of parameters to configure are the idle
 
 ### Idle Air Control Valve Offsets
 
-Load can vary during idle and AC is the most significant factor that can significantly impact the engine load at idle. For engines equipped with an automatic transmission, the load in park/neutral is significantly different from that in drive. It is usually necessary to add IAC duty cycle/air to compensate for the torque required to spin the AC compressor. Again, it is crucial to ensure that AFRs don't swing excessively when moving between different idle operational areas. In the idle settings, start with about 10-15% for the *A/C adder (%)* parameter. As the AC increases the alternator load, the engine torque also needs to increase when the AC is enabled so it is recommended to do this by increasing the engine RPM by 100-200 with the *A/C target adder (RPM)*. The cooling fans also have associated adders (*Fan #x adder(%)*) although these don't usually need to be increased unless you notice a significant drop in RPM when the fans come on.
-
+Load can vary during idle and AC is the most significant factor that can significantly impact the engine load at idle. For engines equipped with an automatic transmission, the load in park/neutral is significantly different from that in drive. It is usually necessary to add IAC duty cycle/air to compensate for the torque required to spin the AC compressor. Again, it is crucial to ensure that AFRs don't swing excessively when moving between different idle operational areas. In the idle settings, start with about 10-15% for the _A/C adder (%)_ parameter. As the AC increases the alternator load, the engine torque also needs to increase when the AC is enabled so it is recommended to do this by increasing the engine RPM by 100-200 with the _A/C target adder (RPM)_. The cooling fans also have associated adders (_Fan #x adder(%)_) although these don't usually need to be increased unless you notice a significant drop in RPM when the fans come on.
 
 ## Open Loop Idle
 
-Tuning the open loop idle is the first step in achieving a stable idle. In some cases, an open loop idle may be good enough for your purposes although it is highly recommended to set up a closed loop idle after perfecting the open loop. To start with, you must decide on what RPM the engine should idle at. To determine this, you must consider various factors such as flywheel and rotating inertia, driven accessories via belt or gear, noise level, personal preference, among others. It may involve an iterative process of selecting a target RPM, attempting to achieve it, and revising expectations. Generally, higher RPM idling is more manageable because the engine produces more torque. Although it is not used in the open loop idle configuration, open the _Target RPM_ table in the idle settings and put in the target RPM you decided on. In the table, it is recommended to taper the idle RPM from about 200 RPM higher than target when the coolant temp is at about 20C to the actual RPM target at 60C approximately. This is to compensate for the extra drag on the engine as it heats up and the tolerances become looser. 
+Tuning the open loop idle is the first step in achieving a stable idle. In some cases, an open loop idle may be good enough for your purposes although it is highly recommended to set up a closed loop idle after perfecting the open loop. To start with, you must decide on what RPM the engine should idle at. To determine this, you must consider various factors such as flywheel and rotating inertia, driven accessories via belt or gear, noise level, personal preference, among others. It may involve an iterative process of selecting a target RPM, attempting to achieve it, and revising expectations. Generally, higher RPM idling is more manageable because the engine produces more torque. Although it is not used in the open loop idle configuration, open the _Target RPM_ table in the idle settings and put in the target RPM you decided on. In the table, it is recommended to taper the idle RPM from about 200 RPM higher than target when the coolant temp is at about 20C to the actual RPM target at 60C approximately. This is to compensate for the extra drag on the engine as it heats up and the tolerances become looser.
 
 ### Idle Airflow
 
-The first step of tuning the idle RPM is to set up the open loop idle airflow. Suppose you aim to set the engine to idle at 800 RPM (minimum), the airflow must be tuned to make the engine idle 50-150RPM higher than the 800 RPM target. This can be done by adjusting the *Open loop base position (%)* parameter, the idle adjustment screw, or the throttle end stop. It is recommended to tune these adjustments so the *Open loop base position (%)* parameter (which is the base duty cycle of the IACV) is at about 30% when the engine is idling 50-150RPM above target. This gives some room for the closed loop controller to adjust the duty cycle. It's essential to ensure that AFRs remain stable as you adjust the airflow. Before enabling idle control, a stable foundation is necessary. In this example, we will say that the engine idles at 950 RPM (150 RPM above target) with 10 degrees of timing, 1.0 lambda and 30% IACV duty cycle.
+The first step of tuning the idle RPM is to set up the open loop idle airflow. Suppose you aim to set the engine to idle at 800 RPM (minimum), the airflow must be tuned to make the engine idle 50-150RPM higher than the 800 RPM target. This can be done by adjusting the _Open loop base position (%)_ parameter, the idle adjustment screw, or the throttle end stop. It is recommended to tune these adjustments so the _Open loop base position (%)_ parameter (which is the base duty cycle of the IACV) is at about 30% when the engine is idling 50-150RPM above target. This gives some room for the closed loop controller to adjust the duty cycle. It's essential to ensure that AFRs remain stable as you adjust the airflow. Before enabling idle control, a stable foundation is necessary. In this example, we will say that the engine idles at 950 RPM (150 RPM above target) with 10 degrees of timing, 1.0 lambda and 30% IACV duty cycle.
 
 ### Idle Ignition Table
 
@@ -47,7 +46,7 @@ The first step of tuning the idle RPM is to set up the open loop idle airflow. S
 
   Closed loop idle control uses a combination of closed loop timing adjustments and idle air control valve adjustments to achieve a stable idle. Achieving a stable idle can be difficult as it requires tuning two separate controllers which operate in parallel to control the engine RPM. The best way to achieve a good idle is to use the closed loop idle timing for the larger and quicker corrections with the idle air controller acting to compensate for slower changes.
 
-  Before tuning the closed loop idle, you need to have properly tuned the idle VE, idle ignition table and open loop idle control. To tune the closed loop controllers, you also need some understanding of a closed loop controller called a PID controller. [This video by RC Model Reviews] (https://youtu.be/0vqWyramGy8) perfectly explains PID controllers in basic terms.
+  Before tuning the closed loop idle, you need to have properly tuned the idle VE, idle ignition table and open loop idle control. To tune the closed loop controllers, you also need some understanding of a closed loop controller called a PID controller. [This video by RC Model Reviews] (<https://youtu.be/0vqWyramGy8>) perfectly explains PID controllers in basic terms.
 
 ### Closed Loop Timing
 
@@ -55,7 +54,7 @@ The first step of tuning the idle RPM is to set up the open loop idle airflow. S
 
 ### Closed Loop Idle Air
 
-  Closed loop idle air control is a powerful tool, but one that requires extreme caution as it can dramatically impact the engine RPM. Even small changes in airflow can have a significant impact, and this is compounded because the speed which an electronic throttle body or idle valves operate is much slower than spark control. To effectively use closed loop air control, a deadband of about 50-100RPM must be established around the target to allow for minor corrections to work. 
+  Closed loop idle air control is a powerful tool, but one that requires extreme caution as it can dramatically impact the engine RPM. Even small changes in airflow can have a significant impact, and this is compounded because the speed which an electronic throttle body or idle valves operate is much slower than spark control. To effectively use closed loop air control, a deadband of about 50-100RPM must be established around the target to allow for minor corrections to work.
 
   In the _Closed Loop Idle_ box in the idle settings, the controller should be set up with a very small proportional gain and a sufficiently larger integral gain. This ensures that the idle air controller reacts slowly and only to relatively large disturbances which the closed loop timing cannot compensate for itself. You may need a very small derivative gain however the controller should react slowly enough that it might not be necessary.
 
@@ -63,4 +62,4 @@ The first step of tuning the idle RPM is to set up the open loop idle airflow. S
 
   To assist in the overall effectiveness of the controller, the minimum and maximum duty cycle variation of the entire idle air controller can be clamped. This effectively limits how fast and with how much force the idle controller is allowed to increase or decrease the RPM. A safe range for the _Min_ and _Max_ is -10 and 20 respectively however these values can be changes around if the controller is responding more or less than you desire. For example, sometimes it is worth putting the maximum to a value such as 50 so that the controller has the authority to bring up the RPM if it gets sufficiently low.
 
-  Another setting of interest that should be used sparingly is the _PID Extra for low RPM(%)_. This effectively gives the controller a kick if the RPM gets too low and needs to take dramatic action. This parameter can be used to compensate for the recommended small proportional gain which is usually responsible for kicking the RPM up if it deviates too far from target. Realistically a well tuned idle controller shouldn't need this but the world isn't perfect so this serves as a band-aid for scenarios where the controller is struggling to increase RPM and is at risk of stalling. Normally, set this to 0% but if you absolutely can't fix an idle drooping problem, experiment with values up to 100% gradually increasing the percentage until the idle is kicked up to around target. Be sparing with this as a high percentage can kick the RPM way above target causing an unstable idle.
+  Another setting of interest that should be used sparingly is the _PID Extra for low RPM(%)_. This effectively gives the controller a kick if the RPM gets too low and needs to take dramatic action. This parameter can be used to compensate for the recommended small proportional gain which is usually responsible for kicking the RPM up if it deviates too far from target. Realistically a well tuned idle controller shouldn't need this but the world isn't perfect so this serves as a band-aid for scenarios where the controller is struggling to increase RPM and is at risk of stalling. Normally, set this to 0% but if you absolutely can't fix an idle drooping problem, experiment with values up to 100% gradually increasing the percentage until the idle is kicked up to around target. Be sparing with this as a high percentage can kick the RPM way above target causing an unstable idle.