I have pinging noise coming from my motor after it has warmed up it sounds just like when you run cheap gas and it knocks and pings it does not do it when the motor is cold only after warm up and the motor is up to temp i have replaced spark plugs wires ,cap rotor coolant temp sensor and am getting ready to change the knock sensor by the way it has not thrown a check engine light and still has plenty of power even though it pings if someone knows whats up with this please let me know its a 1991 rs tbi 305 w/ 5 speed thanks oh yeah i have ben running high test gas and have changed stations thinking it was the brand

 

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Sounds like an EGR valve problem. Either the valve isn't opening when it should, or the exhaust passages feeding the valve are plugged up (very common). Opening up the passages typically requires removing the intake to get it properly cleaned up.