Is there a for sure way to tell if the ECM is in Open or closed loop?

[MustangLX-5.0]

Thread title says it all. And what types of codes WONT set it into Open Loop? Is there a way to tell with one of those plugin actron scanners? ECU junkies get in here..

 

[SpartaPerformance]

Outside of the check engine light being on the ECU will be in open loop during cold start, once everything warms up it will go into closed loop and begin taking readings from sensors.

 

[HISSIN50]

It should take 30-120 seconds to achieve CL if the heaters are functioning on the O2's.

If you watch your O2 readings with a DMM, you can see when they start switching properly (when cold they have very little amplitude and almost no frequency).

 

[MustangLX-5.0]

So during the first few minutes, the O2 sensors are non-functional? I just want to make sure the engine is going into CL. Just trying to figure out what would be making it surge, eating gas, and backfiring at random intervals. Even when it's not doing most of this, it seems I have lost power. I'm running out of ideas on this.

As for the CE light, these cars are notorious for not setting a CE light even when there are problems. For example, it WILL set a CE light if I unplug the TPS sensor, but all those KOER codes I constantly get, it NEVER sets the light off. I know it's not those "newer" cars with the OBDII and CAN PCM's ,but it seems the newer the computer type, the more the CE light will go off for even the littlest things. EEC IV however, it takes unplugging a sensor to trigger that.

 

[HISSIN50]

The O2's are ignored while they warm up. Data from them is used during other OL conditions however (i.e., WOT on a warm engine).