Can you get a scope trace for that expands the first part of the injector signal? Often the first pulse is longer then followed by a series of short pulses to hold the injector. Also play with the trigger level and slope to see if there is another part of the pulse you might be missing. It's interesting the way the trace curves up a bit at the far left of the trace. Looks like it might be coming off another part of the total injector signal rather then being steady at rest prior to the part of the trace shown.
In this thread posts 80 and 82 show some other scope readings for comparison.
http://ecomodder.com/forum/showthrea...rror-6841.html Later in the thread there are some scope traces showing an inverted but similar signal. In that case either the high side of the injector is being switched by the ECU or the person had the scope signal inverted somehow.
A re-triggering timer pulse is the way to condition this signal so your on the right track. I expect it could be done with a 555 timer but I prefer to work with one-shot timers such as CD14538 or 74HC123 for greater flexibility on selecting the trigger edge or inverting the output. There are many circuit options for the function, select the one you prefer to work with.
With a signal that is normally high and has the initial longer pulse I would set up to trigger on the rising edge and use a pulse width that is about the length of the initial longer pulse. The length of the timers pulse is not critical because you will be fine tuning the pulse length in software anyway. The limits are it must be longer then any gaps between the pulses and shorter then the shortest injector total pulse. When selecting components for the RC part of the timer circuit I would use 1% resistors and NPO or other temperature stable capacitor to have a timing pulse that is stable over a wide temperature range.
Mike