I'm not challenging the rationale, just trying to understand/learn. If the Mode $06 data confirms a misfire on cylinder #2, wouldn't running a cylinder balance test just confirm that the remaining 5 cylinders are contributing relatively equally, but not really confirm whether or not there's an issue with cylinder #2? Maybe that was the intent - to confirm there's not a more serious issue with the rest of the engine besides just cylinder 2.
Ah that’s actually a really good question, and you’re not missing much. You’re right that a traditional cylinder balance test (as done by FORScan) just proves that each other cylinder contributes roughly equally. It doesn’t “wake up” a dead cylinder it just shows what happens when you purposely cut fuel/spark to the good ones.
Mode $06 reports misfire counts per cylinder. If #2 shows a high count while the others are near zero, that already confirms:
The PCM’s based misfire monitor
sees #2 slow the crank more than expected.
The miss is repeatable and not random across multiple cylinders.
So Mode $06 is your
first proof of yes, it really is cylinder 2.
I would think of it like layers:
Mode $06: Shows which cylinder is counting misfires.
Power Balance: Shows how much each cylinder contributes, relative to its neighbors.
Contribution Cut-Out (Balance): Confirms that killing a good cylinder drops RPM, but killing the dead cylinder has no effect or proof that #2 was already dead.
So yes, your understanding is right, it’s not magic that diagnoses the cause of #2’s issue, but it does validate that #2 is the only real problem and the rest of the motor is happy.
