Thread: megasquirt idle
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Old 09-04-2020, 02:11 PM   #11
142 guy
Board Member
Join Date: May 2014
Location: Saskatchewan, Canada

The idle / ignition advance control in MSExtra is meant to help stabilize idle speed for small idle speed variations. Not really an idle speed control mechanism. The idle advance is normally only activated when the TPS shows closed, the RPM is less than around 1000 RPM and the engine is up to operating temperature. You can fiddle those settings; but, you are trying to get the idle advance system to do something it was never intended to do. The advance curve that you program in would normally raise advance when idle speed drops below your target idle speed and reduce advance when the idle speed rises above your target idle speed.

You could set the idle advance to control around your normal target idle speed (800 - 900 RPM?). You would normally have it deactivated during warm up or doing a hot start so it will have no benefit during those operating conditions. The idle advance system is not designed to make big changes in idle speed control, that is what the idle air valve is for. If you try to bodge it by opening up the parameters and allowing huge amounts of advance or retard from base setting you are likely going to create transition issues going from idle to driving or find that the system is fighting you during the warm up period.
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