My car is making this loud clicking noise when running and the power has been very sluggish. I know i have an exhaust leak, but it makes a different noise (an air sucking noise). I was wondering if you think this is the knock sensor i keep reading about. I fixing to have the exhaust leak fixed (pretty sure a bad manifold stud and was wondering if you guys think i need to replace the knock sensor also. The car has had no major problems in the three years i have had it and its got 208k on it. Thanks for all the help.

pull codes off the ecu first..my car also has this weird ticking noise..could be a valve..ill drive it till it dies..although when i changed from reg to synthetic the noise is lower

So what does the knock sensor do? Is there a performance increase by changing it out??