decel idle controle (holds 1100rpm until fully stoped) idle question

[90gst_sean]

I've noticed this feature seem a little sporadic. 80% of the time it will hold my rpms just above 1k until I stop, but sometimes it seems to not work correctly.

When the feature stops holding idle, I'll have issues with low idle at low peed; around 500rpms.

I'd like to know if our car are even meant to have this idle hold feature and what could be causing the random malfunction of it? A sensor going bad?

Its been hard to narrow down, but seems to happen more often after a fully warmed car is turned off, sits a short time, them started up. Shortly after leaving, maybe the next stop, I'll notice the problem occurring.

This doest always happen though, and has not been a big problem. I've become a costume to blipping the throttle when coasting in neutral at low speed; but would like to fix it just the same.

 

[absolute_DSM]

Thats a interesting question, Im anxious to know how that works also.

In theory, the speed sensor may tell the ECU the car is still moving so it keeps the throttle up until you stop moving.

 

[turboglenn]

My car has a stand alone where there's no speed sensor fed to it, and the ECU does the same thing to me at idle when coasting. I've come up with a ton of theories, but nothing solid. I have a feeling it has to do with the air fuel ratio fluctuating lean at idle decel.

 

[90gst_sean]

http://www.dsmtuners.com/forums/articles-engine-fuel/54439-idle-control-theory-operation.html

I found this, but it didn't confirm or deny anything really.