'02 sensor stuck rich, bank 1' CEL. Car is running rich on ONE cylinder. weird prob.

[nimski62]

Ive always suspected the car to be running rich, but finally got a code for it. I pulled the spark plugs on that bank and found only the #1 plug to be EXTREMELY black and carbony and gunky. The rest of the 3 were perfect.

I thought it was a faulty injector, so i swapped it with another one.. no change, still running rich on cylinder 1. I can tell its running rich bc that banks exhaust tips are super sooty black. Car has no performance decrease, and im guessing if this problem persits, the cat and 02 sensors are going to go out.

Most problems (such as bad fuel pressure regulator) would cause the whole bank to run rich, correct? what would only cause one cylinder to run rich? very puzzled, have been for quite a while now. helP!

[Justincredible]

Check the coil pack move that around there might be a weak pack then tend to go bad. I had a #5 cylinder issue such as what you are talking about. turned out to be the coil pack. IF you change one you might want to look into changing them all. But swap coil packs and then see in about 50 miles. It will take some time to clean the plug and cylinder out.

You also might want to look into new 02's once they get coated they tend to start reading bad

[nimski62]

Check the coil pack move that around there might be a weak pack then tend to go bad. I had a #5 cylinder issue such as what you are talking about. turned out to be the coil pack. IF you change one you might want to look into changing them all. But swap coil packs and then see in about 50 miles. It will take some time to clean the plug and cylinder out.

You also might want to look into new 02's once they get coated they tend to start reading bad

Bought a new one and installed it already. No change.

Now, to your knowledge, do you know if the 'coated' o2 sensors would make only ONE cylinder run rich? wouldnt it be the whole bank that the o2 sensor controls?