Passenger side spark plugs are black

Hello,

Usually black sooty spark plugs is caused by an overly rich condition. This could be caused by a bad upstream O2 sensor. Can you double check and make sure the spark plugs from the other bank and this bank are exactly the same. Another cause could be a different heat range spark plug was used on this bank and not the other. Just a possibility. Is your Malfunction Indicator Lamp (MIL) or "check engine" light illuminated? In the diagrams down below I have included what the Original Equipment Manufacturer (OEM) recommends for spark plugs and what the gap should be. Please go through these guides and get back to us with the information we requested.

Thanks,
Alex
2CarPros

thank you. will check o2 sensor.

Hello again,

Also is you MIL illuminated? If it is, this would be a great place to start. If you could also check to see if it is, and if so could you please pull the code(s) for us. Here is a link below for you if you are unfamiliar with how to do this:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please go through this guide, if needed, and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

MIL is not illuminated still idling rough haven't gotten any codes yet still wondering why #2,4,6, and 8 were carbon coated and #1,3,5, and 7 were not.

Hello again,

Another thing to check would be a make sure you do not have an exhaust leak on that bank. If your exhaust manifold gasket has failed or where the midpipes bolt to the manifold has come loose, the extra air entering the exhaust would be interpreted by the O2 sensor as a lean condition and richen the mix on that bank of cylinders. If you have a scan tool that can read live data, that could let you know what the short term fuel trim is doing and also what the O2 sensors are doing when in closed loop. Please keep us informed.

Thanks,
Alex
2CarPros