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Old 05-21-2013, 11:12 PM   #1
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Default Closed loop idle help

I have played with closed loop idle but have not had success yet. On initial start up and small throttle inputs the pid seems to work as desired. If I rev to 3000 rpm the idle hangs around 1400-1600rpm. Sometimes it is able to drop enough to enter closed loop other times it will not. I am using standard activation for PID. I have tried playing with the three lockout settings but it does not improve. What would cause the IAC to stay open (34%) and hang above entering closed loop idle?

Also what is Idle Activation RPM adder? It seems that this should be set around my desired idle, not 200-300rpm??

If I read the manual it seems like it should be more than one number: "This setting controls the RPM below which the PID algorithm is engaged, and the RPM above which PID is disengaged, and the close taper (if a Close delay setting is used, detailed later) is started. This setting should be set in the 200-300 rpm range for best performance."

94 Miata with MS3x
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File Type: msl test.msl (350.5 KB, 55 views)
File Type: msq CurrentTune.msq (176.8 KB, 198 views)
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Old 05-22-2013, 11:03 AM   #2
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bad lockout settings
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Old 05-22-2013, 07:14 PM   #3
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Ok lets test my reading comprehension.

"PID lockout rpmDOT threshold - This is the first of the PID lockout detection settings. Use this setting so that the code can tell the difference between decelerating with closed throttle (engine braking) and sitting at one RPM. Set this as low as possible without being below what is normal rpmDOT jitter with the engine RPM not changing. Typical values will be between 50 and 75 RPM/sec."

rpmDOT values above this setting will lockout PID

"PID lockout max decel load - This is the second PID lockout detection setting. The code assumes that if MAP is lower than this setting, the driver must be decelerating, and not "locked out" of the PID loop. Set this to a value just under the load seen with an idle slightly higher than the current target RPM + the Idle Activation RPM Adder. This can be done by temporarily switching to warmup-only mode or idle test mode, and setting the valve position manually."

load values above this setting will lockout PID


"PID disable RPMdot - A good value for this setting will typically be in the 200-400 RPM/sec range. If the engine speed suddenly accelerates with no throttle input (like if the clutch is engaged while the car is rolling and in gear), it must accelerate at a rate greater than this setting before the PID code will be disengaged. Setting this value too high can lead to stalls after engaging the clutch in this manner."

rpmDOT values above this setting will disengage PID
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Old 05-22-2013, 07:54 PM   #4
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Current settings:

lockout rpmdpt threshold: 150 rpm/sec

lockout max decel load: 31

disable rpmdot: 1000

It will be in closed loop until I rev. I dont see which values are not getting met and keeping cl idle from engaging after a rev. What am I missing? Is there anyway to tell in the datalog when cl idle is on?
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Old 05-27-2013, 02:36 PM   #5
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Finally got a chance to play with this again. The damn idle screw was cranked way out. The car will now stall if I command 19% and cl idle is able to kick on around 1300-1400 rpm.
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