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How To Tune Closed-Loop Idle 
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Joined: Tue Jan 15, 2008 2:31 pm
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This brief guide describes something that isn't yet possible with FreeEMS, but will be soon. It's very easy, but the first premise of any closed-loop
system is a stable and fairly accurate open-loop calibration. Without this the control strategy CAN NOT WORK effectively or even at all.

Note: Closed-loop refers to ANY type of control strategy with feedback. Idle means the speed at which the engine sits during its rest
state. Closed-loop idle means controlling that speed using a control strategy with feedback.


Perform all of the below without headlights, aircon, large stereos, etc active. Such devices can be used to evaluate the PID setup afterward.

  1. Give your engine just enough air-flow to survive a cold start at slightly too low an RPM and hold at slightly too high of an RPM once warm
  2. Tune your engine temperature enrichment curve(s) to facilitate acceptable running during the cold start period
  3. Close off the fixed airflow such that the idle valve will do all of the work, especially important with big Bosch valves
  4. Setup open-loop idle control, and set a curve of duty/steps vs. engine temperature that provides a pleasant RPM at all temperatures (eg 1500 cold, 800 warm)
  5. Setup a target RPM vs. engine temperature curve that matches your unloaded reality as provided by the open-loop curve
  6. ONLY now should you engage closed-loop PID engine speed control and tune the PID parameters in the normal fashion


I'll put another post in with respect the extra settings, etc. I'll edit this one to update anything. A questions/comments thread is available: viewtopic.php?f=54&t=2238


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Fri Aug 09, 2013 2:30 pm
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