Current Ramping Quick Quiz

Clue: You can’t “ramp” current without a picture, therefore a DSO is required.
“System Knowledge” is a wiring diagram. Choose your own test points, but know what to expect at same.
On the Fourth Question, using your DSO, observe the quality of the current-draw waveform. Commutator dropouts will inhibit fuel delivery, with multiple effects.
As for “directional”, you DO KNOW that you are dealing with Direct Current in most current automotive electrical systems? Personally, I have forgotten the “closed fingers- thumb rules”, but get by OK.
But, on Question Number Two: Let us not become involved in over-intricate technicalities when attempting to diagnose the problem at hand. A) Ignition Misfires often can be identified on Scan Data or Mode 6. B) Fuel pumps are usually pressure and/or volume. Yes, marginal pumps can be suspected, but until they FAIL in front of you, it will always be a roll-of-the-dice. C) The TYPE of injector system is an important factor. SEFI or MPI ? As always, when suspected, access to individual injectors is often difficult. Here a shorted injector in an MPI system will skew injection control. In an SEFI system it should throw-off an individual injector failure OBDII code. But, maybe not. Elevated STFT/LTFT values may help, but injector failures are rare in my experience.