Need to actually remove the sensor from the pipe. If your cat's clogged or on it's way out removing the sensor will help relieve some of the pressure...

 

Alright i was just out there trying to unscrew the O2 sensor and it stuck in there really effing tight. i sprayed some PB on it and im gonna try again in a little bit.

Does taking the sensor out really free up that much room to relieve pressure??

 

It helps. It won't be 100% but, if that's the problem you'll see an improvement.

 

Need to physically remove the sensor from the exhaust. If it doesn't reset the misfire code, the cat is on its way out. Cylinder 8 is the 'indicator' cylinder for bad cat. It usually starts misbehaving first when the cat starts plugging up.

 

This is a good indicator. The cat was replaced 3 years ago, but the plenum was just replaced. This tells us that the plenum crated the cat (3 years ago) and the symptom (caat) was replaced, but the problem (plenum) was ont corrected....until now. This pretty much gaurantees that the cat has succumbed to the plenum issue. The good nees, this should be the last cat failure. bad news - cats are not cheap. But I bet this will solve your problem.

 

just something else to check but I had a misfire on #1 caused by a cracked header.. Also, Did you change the cap , rotor and wires?

 

Cap rotor and wires were all changed last summer and should be in good shape. Today I'm gonna try and get the O2 sensor out and see if that resets the cylinder 8 misfire code. I'm really hoping it'll do the job cause I'm not looking toward to a possibly cracked head.

 

Having a really tough time here. Tried to get the O2 sensor out but that thing is crazy stuck and the bolt is starting to round. not sure its gonna come out.

 

go buy a o2 socket.. <$10... worth it's weight in gold when you need it..

that plug looks rich to me.. put a screwdriver on your injector, the other end to your ear.. listen for poppitypoppops.. compare it to other injectors.. see if they are similar..

 

The o2 socket it was rounded it. I rented one from autozone. The deep socket with the slit in the side for the wire. The thing wouldn't budge at all