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Idle hunting needs improving

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Old 06-03-2022, 12:40 PM
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Default Idle hunting needs improving

I have a 2001 Miata, FM Garret 2560 turbo kit, MS3PnP controller. Detschwerks 650 injectors (or so, forget exact part name).
I am having trouble with idle hunting, or oscillations. It does not always happen, and I can't sort out why it is happening when it does. It often occurs when getting out of the throttle, and seems to fail to see it should be going in to idle, so lets rpm drop too much.So looking for some guidance.
I increased the dash pot damping a bit, which helped in some cases, but these below are still occurring. I richened the idle a bit, but the amount it wants varies a lot with coolant temperature it appears, less so with intake air temp. I assume this may be temp sensitive coils inside the injectors.
Parts of the controls seem to be working against each other, but I am not sure which to adjust at this point.
Here is an example:
This is right after warm up, plateau around 185 deg. The Intake air control valve PWM, and PW on the fuel are working in unison, but out of phase with the idle rpm, always trying to catch up.



Here is another example, after driving normally around town:
In this case a lift off the throttle coming up to a stop sign, the tps dot triggers a brief decrease in fuel injected, and then returns to normal, but the AFR briefly goes way rich anyhow, the PWM rises but is fairly stable, while the PW oscillates, eventually inducing oscillation in the PWM as well.


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Old 06-06-2022, 08:35 PM
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Default

Below are a few things that I recommend. These are a start to get you closer. There are several recent threads on the idle. A little reading will help you a lot.

Why no ego correction?
Raise the target idle rpm to 900-950.
Change the cranking rpm to 300
Under the closed idle settings, switch the use last value to table and make the appropriate adjustments to the table.
Also decrease the dash pot adder and raise CLI PID gain to 500-700.
Turn off idle advance and keep idle rpm timing cor on. Make the timing correction more aggressive.
The timing table needs help. 10-12 is best for idle.





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