Ultragauge DFCO observations

[SilverCrown9701]

In my 2001 Toyota Camry, if I am in overdrive at any speed above 45 MPH, then DFCO will activate and show 999.9 MPG until it downshifts into 3rd gear and decreases below 1,400 RPMs. After that, it will read 75-100 MPG, depending on terrain and weather conditions.

[SilverCrown9701]

Also, I noticed that when using cruise control when the computer forces my car to downshift to maintain the constant speed, during the downshift, my UltraGauge will read 999.9 MPG and cause my Average MPG gauge to increase.

This goes against what I've learned about cruise control. Is this normal? Is it really saving fuel???

[California98Civic]

Once the ultragauge shows DFCO as 0.000 volts on the primary O2 sensor, the reading will stay zeroed-out in second gear until the car hits idle speed and needs gasoline to keep from stalling.

[firehawk618]

Could it be a leaky fuel injector? When you hit DFCO your injectors are at zero duty cycle and you should almost immediately see your AFR's peg out full lean.