Subaru Repair: 02 impreza engine knock, timing belt tensioner, engine knock

Question
I have an 02 impreza 2.5rs. I have put a cold air and cat back exhaust on it. For about five months the car ran great but lately I've been getting this wierd engine knock at idle. Also noticed that when at idle the engine is falling below 500 rpms. Don't know if its the vaulves or what. Tried changing oil running full synthetic and 93 octane but doesn't seem to do anything. Please help

Answer
Hey Brock,

It may be the timing belt , timing belt tensioner or the bracket, there is an updated bracket for the timing belt tensioner due to a knocking type noise, or it could also be one of may other things as well.

Its hard to correlate the knocking noise to the low RPM and running poorly though.

Justin

www.allwheeldriveauto.com