Sorry if I was vague, was posting in a rush.
Yeah the RL box splices in series with the VEMS injector outputs. It doesn't actually open or close the injectors, it simply breaks the given circuit when it wants to misfire a cylinder during a loss of traction situation. So when idling, the RL box isn't doing anything actively.
The way these boxes are wired into the injectors is that you add a male and female connector inline, and the RL harness has a matching set for each end. So it's easy to eliminate the RL box from the circuit to see the effect. With the RL box plugged in but not doing anything, the car idles much leaner.
I think I follow your logic about this meaning that the injectors open/close slower but then I don't understand how the calculation works then, why would it go leaner if the injectors are slower, and then richen with a higher deadtime? As I understand it, the deadtime is basically like an extra area under the pulsewidth curve, sloped sides instead of a square pulse. To get the amount of fuel right, the shallower the slope, the more the ecu will reduce the pulsewidth, to keep the area as desired. So if the slope becomes shallower than what the ecu thinks, wouldn't that result in too much fuel?
Purely symptom wise, it seems to indicate that the injectors open and close faster - leaner = less fuel going in. So with the pulsewidth being the same in both cases, the only factor is the deadtime being lower. But instead, INCREASING the deadtime made the engine run right.
Maybe the lean values were actually incomplete/failed combustions from too much fuel
