[mwebb]

blue is injector signal
in the image above
in the upper left is the screen this image was culled from , note the gap in the blue trace .
that gap is DFCO , there was no injector signal from the ECM during the gap .

i captured this by snapping the throttle to WOT then releasing it , allowing the engine to slow down from the speed it reached during the WOT snap , as soon as the TPS shows closed throttle and rpm is hi
the ECM shuts off fuel , the ECM starts fuel back up when it sees rpm falling below the value it was programmed to restart fuel at .

all newer cars have DFCO .

if your car does not Have functioning DFCO , the first thing to check is the TPS or closed throttle switch , because if the ECM does not know the throttle is closed , it will not activate DFCO