ATTappman

Here's some waveforms for the major sensors and an injector and coil on a 97 Maxima, measured using a Picoscope. All the sensors are good. In case you wonder what's going on under the hood. Sorry for the small size of the fonts used for the axis labels, Pico doesn't allow control over that.

Crankshaft position sensor (POS):
This is a 0-5 V square wave. ECM supplies 5 V, sensor pulls it to ground in between the teeth on the flexplate or flywheel.


Crankshaft position sensor (REF):
AC signal, with a doublet every time the crankshaft completes a revolution. Cylinders hitting TDC are numbered.


Camshaft position sensor:
AC signal, number of peaks indicates the cylinder at TDC. Signal pulse to coil #2 is shown in read. Cylinders are numbered.


Injector voltage and coil current:
Injector ground side voltage in blue, coil current in red. Injector is pulled to ground to open the pintle, then there's an "inductive kick" as the magnetic field across the solenoid collapses. You can see a small dip in the current ramp (in red) as the pintle opens, and the small hump in the voltage (in blue) as the pintle closes.


Front O2 sensors:
Idling at 2500 rpm, in closed loop. These sensors have 140,000 miles on them, so they might be a little slow.


TPS:
Throttle plate being opened manually, then closed, then opened again.


MAF sensor:
Snap throttle test. Voltage jumps up as air flows into the manifold, then decreases because the engine can't keep up, then comes back up until the throttle is finally released. Wiggles are the individual intake valves opening and closing. Voltage peaks around 3 V, the hot wire might be a little dirty.

DennisMik

iTrader: (2)

That is great stuff. There are times I wish I still had a scope when working on a car.