M900ie coughing through intake

[sdl2112]

14.58 is high, how accurate is the meter you are using?  Maybe I am not understanding something, but the voltage going to the coil is voltage amplified by the module when the engine is running, no?  Is the oscilloscope an automotive type?  If so, you can measure available voltage to the plugs by pulling the connector away from the spark plug and watching the voltage increase.  Do not increase the gap enough to cause misfire, since you can damage the expen$ive ignition module.  You should get over 18K volts.

The meter is accurate, it's a nice Fluke meter.

I'm just measuring the supply voltage that goes to the primary side of the coil.  It's just the battery voltage that first passes through fuses and a relay.  The ECU charges the coil by completing the the circuit to ground, then releasing the the energy as a high voltage arc.

I'm using a lab type o-scope, good for up to 1kv.

[Howie]

You would check them while adjusting the valves.  While the keepers are off to change shims wiggle the valves in the same plane as the rocker arms.  The clearance is half the play.  Not the most accurate, but, IMO goodnuff.