I've read that the EVO ECU runs in either closed loop mode or open loop mode. Can someone tell me what causes the transition from closed loop to open loop. I've read it runs open loop at WOT so is it based on throttle position? I've also read it will run open loop above 3000 rpms? Is this correct as well? Any other info about closed/open loop is appreciated. Thanks in advance!

 

Anybody?
Bueller?

 

Closed loop is basically (with a few minor exceptions) your idle and part throttle cruising when load is very low, and throttle positions are below 30% (approx)

Open loop Fueling is using fuel and timing maps.. It makes assumptions at a desired volumetric efficiency so the ECU can make fuel/timing decisions much quicker, this is done at higher loads and RPM's

Open loop occurs when the car is cold, and the O2 sensor has not had time to warm up, after 30 seconds to 3 minutes, it switches to closed loop...

Open loop also occurs when there is trouble with the ECU or O2 sensor preventing closed loop operation to maintain an optimum air fuel ratio.

Finally

Open loop occurs at throttle positions above 30%, most performance driving you will do will occur in open loop.. Cruising on the highway, or idling in your driveway is typically the job of closed loop where it will have the best fuel economy.

That work for you?

 

Thanks MalibuJack, that was what I was looking for.