My 05 Monte SS is having some fairly substantial knock when slowly accelerating in high gear and low RPMs. I'm seeing as high as 4-5 degrees. If I push the pedal down farther and let it downshift to accelerate faster the knock disappears. The knock only appears during this time. I've noticed its the worst when cruising and going up a hill. I have a 180 tstat, 2 steps colder plugs, CAI, and headers on the car. I am running 91 octane. It has not been tuned recently.

 

Is your car bogging as well? I'm having similar issues same year and model

 

Not really, I talked with a family friend who has a non SC SS and his does the same thing

 

This is a long shot but be sure its not an exhaust manifold leak causing false knock..

Wouldnt it be great if it was that simple??

 

Well I definitely had a manifold leak when this was occurring. It has died down however and hardly does it. I have fixed the leak as well as ran some seafoam through the car so I can't said which fixed it