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Idle Advance / Load oscillation mystery (Datalog and Tune Attached)

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Old 08-12-2020, 03:26 PM
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Default Idle Advance / Load oscillation mystery (Datalog and Tune Attached)

If anyone is bored today, I would appreciate a second set of eyes on this datalog. There is a very clear oscillation in timing/load that leads to a stall during idle (starts at 400 sec). In this log it appears that the timing is acting as it is being commanded. I cannot account for the specific event of the Load that starts the timing oscillation and subsequent RPM changes. It appears to happen as the CLT crests 199F, so maybe the FAN trigger? But the fan isn't set to come on until 205F... Is there anything obvious that is "switching on" to account for the change in load, and therefore the idle starting to hunt around?

I know that the settings around idle are not ideal, I just plugged in my MS3x for the first time in 5 years and updated the firmware. This is the first startup and up to temp datalog, but just looking around in the tune- there are now engine states and they are on by default in the idle settings. I never had a great idle before, but now the settings are a bit jumbled.

Anything that I am missing?
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2020-08-12_11.30.08.msq (288.6 KB, 26 views)
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Old 08-12-2020, 08:19 PM
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Your idle advance correction is too aggressive. Your target idle is set to 970rpm, and when your car's idle dips around 850-870 your correction tells it to add ~10 degrees of timing causing the rpm to go up. Try this map, only made the correction milder and target rpm to 850.
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Old 08-12-2020, 10:05 PM
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Thanks! I'll take a look. I think this setting is new and the values in the table are the ones that are automatically generated when importing an old tune. I think I also may have an issue of moving off the idle VE table (which has all changed) during wild rpm swings. I may also be triggering an engine state change.

Also I figured out what was happening in this particular log, the thermostat opened at 199, which caused the temp to drop. There may also have been a fan on event, based on an old output based on CLT.

In the process I also discovered advanced fan control ( which is awesome ) I still had a hard coded fan on at 200f in tunerstudio, from before the update, and in the update tunerstudio created duplicate settings for another fan output. It's also great that fan control will turn on the fan with the AC.
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