Everymorning when I start up my car, i hear what sounds like a slight tapping sound from the drivers side engine. Its pretty loud, but when i start to accelerate, or im driving i don't hear it, only at low RPMS.. BUt another thing, is the sound seems to go away once the engine is warmed up, Its not nearly as loud, thats IF i can hear it at all.. The only exception to this, is when i seem to ride the car really hard. I went to Texas Motor Speedway this weekend, and went around the track 3 times.. running the car pretty hard trying to get over the 120 MPH mark before catching up to the pacecar. did this three times around the track and left, (out of money) and when i drove away, i could hear the tapping sound again, and it eventualy got quieter.. I am wondiner if maybe it is either a rocker\valve, or maybe the check valve for the A.I.R tubes.. any suggestions or tips??

 

Could be a few things. Most likely, its a lifter. Bad lifters make noise until they start building up pressure (like a bit after you start it) and then the noise goes away completely, unless you run the car hard in which case it'll lose the pressure it built up and starts tapping again. Other likely suspect is an exhaust leak. When the engine warms up it will be less noisy, but usually once the engine is hot it doesnt get worse and then go away by itself. An exhaust leak you will always hear, it will just get quieter once the engine is warm.