It's really quite simple, let's not over think it.

Fuel cutoff occurs under three stated conditions.

1) During deceleration with the throttle valve closed,
current to the injectors is cut off to improve fuel
economy at engine speeds over 850 rpm (A/T)
(M/T: 907 rpm).

2) Fuel cutoff also occurs when the engine speed
exceeds 7,000 rpm, regardless of the position of the
throttle valve, to protect the engine from over-revving.

3) When the vehicle is stopped, the ECM/PCM cuts the fuel
at engine speeds over 5,000 rpm (A/T) (M/T: 4,800 rpm).

On a cold engine, fuel cut occurs at a lower engine
speed.

Your reference to "The ECU adds fuel under slight loads..." might very well be true, however, it is not part of the fuel cutoff scenario.
If so, w/ lights or A/C on there would be no over-rev protection. Hardly the case.

Deceleration is qualified by needing to have the throttle valve closed.

Again:
The only conclusion I can draw, and the reason I originally posted, is to show that coasting out of gear [essentially in idle mode] is not a way to conserve fuel, as some have falsely assumed.
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The UltraGauge has no ability to see tranny temp, but will see oil temp if vehicle has an oil temp sender.
The FIT does not.
On some diesel engines the coolant temp could possibly be the oil temp.

I do not own a scan gauge.

K_C_

 

There is a lot more to this. But in general your right with the list 1-3. Throttle parameters,Fuel parameters
Then there is temp corrections too. Lambda changes when the weather is cold and that is why mpg falls in the winter.



I understand that there is no flash pro yet but there has been some success with it over seas. The principles are the same.