2003 g35 idle problem

[amedina90]

Hey guys new her to no I club the names Alex.
So I have a really big problem with my 03 g35 haven't been able to figure this out been a real headache wanted to see if anyone could help.
My g35 has a problem when it is started from a cold start it dies out but after 2 or 3 starts it will start to idle better and as soon as the motor is fully warm it runs as if nothing is wrong. The SES light is on it says p0031 which is the o2 sensor bank 1 sensor 1. I replaced it with a brand new one and still throws out the same code. Took it to a mechanic and he couldn't figure it out. And one more thing it also starts to misfire when I'm on the freeway then idles rough again but after a few minutes it goes away and I have one bad cat on drivers side.
I have changed the the o2 senso, thermostat, mass airflow sensor, both can sensors, and one ignition cool that was bad but no progress stays the same as always.

Anyone got any ideas???

[joe603]

Have you cleaned the battery terminals? Not sure if it will help with the code, but the problem idling could be caused by a weak battery and/or bad connections.

[amedina90]

Yea they are cleaned even put a brand new throttle body

[joe603]

Did you try cleaning the throttle body? ...you have to be SUPER careful because the butterfly valves are electronically controlled and will be damaged if you try to move them. That could be some of your problem...

[amedina90]

Yea I did clean the old did idle relearn but I talked to a mechanic he said it might be one of my cats

[RED_DET]

If you don't replace the bad cat, you problems will never be solved.

[amedina90]

Yea that's what I'm waiting on now

[Wil from VA]

I have a 2009 G35. It does something similiar. Every so often, it starts and then immediately dies. This pattern repeats itself. Then magically it starts and stays started. The local dealership says it has to replace the ICC but I am hesitant and its alot.