One Bank of Carbon-fouled Plugs

[ffoote]

My 96GTS was running rough. Pulled the plugs to change them (needed) and the right (passenger) side was clean, looked normal. However, the left (driver) side plugs (all five) were totally black with carbon deposits.
Anyone ever have this happen? Could be PCM, catalytic converter, what?

/f2

 

[GTS Dean]

O2 sensors or plugged cat.

 

[Dom426h]

ffoote, some more details might help

Miles?, Modifications?, Maintenance?

 

[Jack B]

See what a code reader says, also use the reader to look at the LTFT's.

 

[Viper Specialty]

99% says O2 or Plugged Cat as said above. Ignition issues, fuel issues, or PCM would not cause a bank to bank difference, it would affect pairs of cylinders [ignition] single cylinders [injector drivers/wiring] or all cylinders [filter/pump/etc]

 

[Tom Sessions]

How many miles are on the car? Were the plugs just black or did they have a large build up of carbon maybe to the point of closing up the gap? Does the car use oil? Have seen in the past where the valve seals were left off of the cylinder heads and over time would cause the plugs to build up a large amount of oil deposits on the plugs