Inconsistencies with Deceleration Fuel Cut Off

[YHWilliam09]

I'd like to get other people's input on some inconsistencies I've been having with the Deceleration Fuel Cut Off (DFCO). I drive an '09 Liftback Automatic 1.5L.

I have a ScanGaugeII, and I know when my MPG is displayed as 9999 it's in DFCO mode. I've read that it only goes into DFCO mode when the vehicle is engine braking and over a certain RPM.

My issue is that it seems to have a mind of its own when deciding when to switch to DFCO. For instance, when the engine is cold and still heating up, no DFCO. Once the engine is warm, it still won't always go into DFCO even when the RPM is above 1500. Sometimes I can tap the brake pedal, and then it will kick in. Sometimes I can tap the accelerator, and then it will kick in. Sometimes I can downshift to 3rd gear, and then it will kick in. Sometimes it won't kick in to DFCO no matter what I do even though my foot is off the accelerator, and it's engine braking over 1500 RPM.

Does anybody else notice these inconsistencies, or is it just me? I strive to increase my average MPG as much as possible, so it's been a little frustrating trying to figure out this DFCO and when it's supposed to kick in and when it doesn't.