So my engine began to knock and it's starting to concern me. My car has a few other issues ( I think optispark being one of them), but now it's knocking, bogging, sputting, and running rough. When I rev the engine I can hear the knock under the hood on the driver's side bank (I can even hear it during accelerating when I'm driving!) I ran the car when I took it in for an oil change and it pulled O2 sensor and knock sensor codes. Would the knock sensor cause the engine to make as much noise as it does or could it be worse??? Also since I've owned the car I've only put 91+ octain in it to prevent try and prevent this. If anyone has experiance with LT1 problems please send me some suggestions.

 

knocking is from either a spun main bearing or spun rod bearing. Here is what I suggest to do. Perform what is called a "Power Balance test". you say it is from the left bank or drivers side bank so start by pulling off the plug on one cylinder, then ground that plug and start the car and see if the knocking goes away. continue this until the knocking can no longer be heard. When you can no longer hear the knock that is what cylinder has the spun bearing. give this a try

 

Are you sure that this is an engine knock or detonation? If it is indeed engine/mechanical related motox^^ has some good advice on diagnosing the issue.

 

could be the opti is throwing the timeing off causing pre detonation or pinging. if its pinging then the knock sensors will kick in and retard the timing more making the motor lose power and run crappier. if it is a rod knocking u got a major repair coming up.