cold-, warm- & hot-idle control

[dark_knight]

can anyone confirm whether the stock ECU uses just the coolant temp to regulate idling or if it checks both coolant temp and oil pressure. i'm starting to suspect that it uses both -- ever since i got my gauges, i've noticed that at times i can be at 90 deg C coolant temp but oil is still in the low 50s and idling will remain at about 13 hundred until the oil warms up to 65+ then it starts to drop..

 

[Texx]

The stock ECU has not input sensors for either oil pressure or oil temperature. It compares the readings between the inlet air temperature and coolant temperature to identify the need for cold start fuel enrichment, cold start fast idle is determined by the coolant temperature reading alone.

 

[dark_knight]

faster IATS perhaps?

thanks Texx. so the stock oil pressure 'switch' is just hard-wired to the dash-light and doesn't go via the ECU..?
perhaps my engine's different behavior is down to my recently installed quick-acting IATS..

 

[weeJohn]

Oil pressure switch just goes to the dash, there is also the wax stat on the throttle body that controls the amount of air that goes past the throttle plate on idle.

 

[dark_knight]

thanks weeJohn. i've bypassed my throttle coolant line so the wax stat is disengaged on mine, unless the inlet mani soaks up enough heat from the block to melt it..

 

[weeJohn]

Thats why its high idling then, the wax is not heating up and closing off that bypass I would say.