I have a 99 Chevrolet k1500 PU that has a 5.7L vortec motor and it has a engine ping at higher rpm's and it feels like it has lost a little power. I noticed it cranking just a little longer than usual during this very cold spell we have had. I have replaced the fuel pump and filter and the fuel pressure regulator and the fuel pressure is not bleeding down and when the key it turned on it has pressure of 59lbs and drops by 2lbs after about 4 hours. I had the entire upper end of the engine rebuilt just 3 months ago by a garage because it was leaking antifreeze out of a head gasket externally. I replaced the spark plugs and distributor cap and rotor button 8 months ago before I had the engine rebuilt. I have had the timing checked and its within 1 degree of specs, I have put it on a reader and it shows the temperature control sensor to read almost perfect of what the ambient air temp at the air induction within 10 degrees.
Does anyone have any other suggestions?

Thank you
Gregory Agee

 

The knock sensor might be bad.

 

Well I replaced the knock sensor and it made no difference. I did take the truck back to the mechanic and they had to rebuild the upper end again because of the same head was leaking and in the same place and they magna fluxed the heads and found no cracks and they checked the block for any humps or cracks and found everything to be ok. I told them about the ping noise and they said I was missing one nut on the collector at the doughnut gasket and they said that could have been it, but it has been 3 days and the motor is starting to ping again at high rpm's when going into 2nd gear. The timing was dead on and the cam shaft positioning sensor was working good. I am going to try a higher octane in it next time I fill up. Anyone else have any other ideas?