[help needed] wild (?) idle oscillation

[AndreyB]

That's http://rusefi.com/forum/viewtopic.php?f=3&t=699 idling with some autotune VE map and some ignition map from the internet.

What is the root cause of the RPM oscillation? What is the right way to tune idle fuel?

All files are at https://svn.code.sf.net/p/rusefi/code/trunk/misc/logs/1996_Passat/2016-06-19_idle_osc/

[Dial0]

I can't offer much help with tuning the idle fuel.

I think the oscillations are very likely caused by the wandering ignition timing.
On a 4age, the tps has a fully closed switch, when that switch is closed at idle, the ignition timing is fixed at something like 8 degrees.
Often times people mess with the TPS to fix other issues and end up with the switch not closing when the throttle is fully closing.
This means the ecu never goes into the 8 degree static timing idle mode. Which causes the idle to hunt up and down, and sometimes stall when you quickly push in the clutch and let off the throttle.

The only advice I can offer is to set the ignition table to a more static ignition timing in all the cells you are currently idling in, then you can focus on the fueling side without worrying about the ignition.
Then when the fueling is looking better you can go back and adjust the timing?

[AndreyB]

delta(timing) is (just?) 1.5 degree on this log, but I like this idea!