DTC 4201 - Intermittent, and rough running, but NO OTHER CODES!

[packetfire]

Injectors? Wouldn't leaky injectors smell like unburnt fuel?

Cat cleaner... OK, that sounds like something that at least "Can't Hurt". (But I am skeptical of anything other than gas and the fluids that are supposed to be in my car, even if it has also been suggested that I run half a quart of TRANSMISSION FLUID into a full gas tank to "clean the injectors".

[jonesg]

i would remove the plastic engine cover to get access to the coil plugs and wait until it acts up, then you can start unplugging coil connectors and trace which cyl is acting up or whether its systemic.

if systemic , read fuel pressure and trims at the same time when its running rough.

[jonesg]

if you have torque PRO on a smartphone ($5) with a $12 ELM 327 from amazon,
you can set it up to detect misfires that don't register with the ecm.
Its less cumbersome than vida on a laptop with cables.
I leave the ELM 327 plugged in , it doesn't affect the car battery.