Rough Idle Changed O2 Sensor

[frat guy]

Well I did my board searching and came up with nothing really conclusive. For the past week I have had a rough idle. It went from every so often to now all the time. Ran the codes, got a P0304 misfire and a bad 02 sensor. Changed the 02 sensor, I think it helped a little. I'm also getting that sulfur smell, and I can hear the poor idle in the exhaust. My searches came up possible IAC and MAF cleanings for the idle. But I am just wondering since I got the P0304, does anyone know what is most likely to cause that? Right now I can only think plugs and wires as my next step to take. I also sent some PM's to a few I saw in the older threads. I got no reply yet.

Thanks all.

 

[frat guy]

just talked to someone else, they said intake gasket leak?????

 

[marragtop]

Did you reset the codes, and if so is the 304 still coming up? Depending on how old they are, I'd consider wires and plugs before doing the intake. Keep in mind the cat converter if you are getting a sulphur smell. Did you by any chance just start using ethanol in the gas?

 

[frat guy]

i did reset the code. the 304 still came up it said cylinder 4. I guess it would be a good idea to check the plug for that. How do I know which is cylinder 4? And no I have not started using ethanol. But im in colorado, and i understand that 10% of all fuel here has ethanol in it. I just got back from Chicago, I dont think it's like that out there.