[[Manual: Detailed.Control.Idle.Config]]
If the engine spins up too high RPM after cranking and takes too much time for iac-dc (check your logs in spreadsheet or logviewer!!!) to start to decrease, your iac_integral_inc_limit is too high.
If that does not lower the idling speed, then check that the 'TPS value for idle threshold (%)' -> (menu Extras -> Idle Settings General -> Idle Settings page in Megatune) has higher value than the actual Throttle Position value when throttle is closed.
Stalling engine
If the engine has tendency to stall, than maybe the iac_integral_dec_limit is too high. But remember there can be MANY other reasons for this to happen.
The MembersPage/MarcellGal/EngineSwap is a weak 1.6L engine. It often stalled with air-conditioner. The solution was to make the control authority as narrow as possible, with smallest iac_integral_dec_limit and iac_integral_inc_limit values.
Tuning warm engine first (the iac coolant dependent reference positions for lower coolant temp can only be tuned afterwards). This car has stepper iac, but same applies for PWM iac. Eg. the engine needed
- iac position=29 when AC and lights were off (without load)
- iac position=41 when AC and lights were on (max load)
- the AC is much more significant load, the lights is only 1 iac position or less
I set the iac reference position (at max coolant temp) to decimal 38.
- I decreased iac_integral_dec_limit until the engine cannot regulate without load, that is iac position=30 resulted in slightly raised idle (iac_integral_dec_limit was appr 24 decimal in my case, but this also depends on integral value)
- I decreased iac_integral_inc_limit until the engine cannot regulate at max load, => iac_position=40 cannot maintain the idle target (iac_integral_inc_limit was appr 6 decimal, but this also depends on integral value)
Obviously, I increased the limits slightly (from 24,6 in the example to 25,7 or maybe add some more margin and 27,8).
This
- narrow iac authority-range
- and setting the reference position a bit higher than the middle, as 38 is higher than (29+41)/2
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