Hey Guys,

I just experienced this last Sunday & early this morning. My RX300 has a subtle misfire early in the morning when the weather is cold (here in Southern CA it's been in the upper 40s/low 50s in the morning for the past couple days) and then it runs normally when the weather warms up mid-day when I leave for lunch.

Any of you experience that? Thanks in advance for your input.

 

My experience is I have never encountered a "subtle" misfire. Any misfire I've had has been far from subtle (for example, the whole car shakes like it's going to explode when a coil ceases functioning). Could it be a rich mixture (thermostat, sensor, etc not working properly causing the engine to run a little rough)?

 

I say subtle because the misfires are not as strong or pronounced as they were before I fixed my bad #4 plug. Just a little jerking when accelerating. I did not receive any codes.