I have a 2004 5.3l runs really roughat an idle mostly. 40,000 miles check eng light came on and codes po131,171,300 came up.
Checked spark plugs and all 4 on drivers side were black other side was fine.
Any ideas?
Thanks

 

Here's a few links that may help a little:

http://www.obd-codes.com/p0131

http://www.obd-codes.com/p0171

http://www.obd-codes.com/p0300

Probably all three are related to one problem. Your plugs are fouled because the PCM thinks Bank 1 is too lean so it's throwing more fuel to that side. The random misfire code may be related to the plugs being fouled.

I would suspect the problem might be the O2 sensor on the driver's side between the exhaust manifold and the catalytic converter. The P0131 code indicates that sensor has a low voltage (if any) which the PCM interprets as a lean condition. Check the wiring to the O2 sensor for a broken wire or short to ground. You could replace the sensor but that's throwing parts at the problem. You may get lucky if that's the problem but you might not either. A technician can check the sensor for you. I'd start with that and clean the MAF as well.

 

http://www.obd-codes.com/trouble_codes/ this should give you the full list of dtc's and a brief explination... this should at least get you on the right path

 

Thanks guys I will check the O2 and clean the MAP today ...I will let you know.
Thanks again.

 

It was the O2 sensor...Thanks again.

 

I'm happy to see you got it fixed.