does anyone know when an ecu switches from closed loop to open loop? oh yeah, i have a 98 base prelude.

 

I think when the engine is cold, it's running closed loop. I'm definately not sure about this though, i'm pretty sure there are many topics about this.

I belive the ecu switches upon throttle %....just do a search for closed loop and you should have many results returned.

 

closed: operating temp, idle or at partial to 3/4 throttle

open loop: decel in gear to approx 1500 rpm and WOT. also when cold.

 

thanks for the good info , this will help me out with tuning.

 

anyone else want to confirm this?

 

The ecu starts in Open loop- cold engine, this means its below normal operating temps and the ecu uses pre programed info like injector pulse width, ign timing, curb idle, fast idle, ect.

Then switches into Closed loop when the oxygen sensor reaches about 600 degrees F or the engine coolant temp reaches about 120 degrees F or a combination of the two. Also this can vary between manufacture.

This is from my notes from the local technical college. Hope this helps you tune.