2006 Infiniti G35 came in with a rough idle. Car had 200,000km so we replaced spark plugs. Still had slight rough idle. Not quite a dead misfire and sometimes worse than others. Seemed to drive pretty well.
These cars don't have misfire counters so not the nicest to track down. Found bank1 fuel trims to be pretty normal. Bank2 were +15% to +25% total trims. Didn't seem to change much with revving the engine. Didn't suspect vacuum leak and nothing found on smoke test. Clear flood crank sounded pretty even.
Checked secondary ignition waveforms with an inductive probe and all looked good. No dropouts seen even though engine was misfiring.
Next easiest step was to check fuel injector current ramp patterns through the fuse. This lead us to the problem. One was very bad, one was partially lower than the "good" ones and one was slightly lower.
Removed the intake manifold and confirmed two bad injectors and one partially bad injector via testing resistance.
After repair the car felt like it had an extra 100 horse power!
