I have a very noticable ticking sound coming from the passenger side of my engine that sounds like it's coming somewhere around the injectors or valve cover area. It is noticable at startup for a bit and then goes away until the car is under acceleration and it becomes very noticable again and increases with rpm's. When in park reving the engine does not produce this sound, however, putting it in drive and keeping the brake on to keep it from moving but then revving the engine it will begin to tick. So it seems to only occur when the cars is revved in gear for some reason. It's not an exhaust leak as I have checked the system over numerous times. Just replaced fuel injectors which help a bit and just replaced fuel pump.