Just wondering if any of you smarter than me people would know the answer to my question. I have a '95 delville with the 4.9. It has great power and all but when i drive it away from a stop sign while pulling away it is nice and quite and all is well with the world until i let up on the gas just slightly to maintain say 30mph.. while holding this speed it sounds like spark knock.. I use only premium gas in it so i know it is not a octaine issue but what about timing? i just bought this car in st louis and drove it to tampa florida(1000 miles) and had no other problems except the low oil pressure warning ( which i knew about allready) and it only does that when the oil gets hot and you stop and idle.. if you give it any gas at all the warning does not come on.. I think it is a pressure switch and i have bought a new one (ac delco) and will put in on and change the oil and filter and see if i still have that problem.
thanks in advance
wolfy
aka Roy

Just wondering if any of you smarter than me people would know the answer to my question. I have a '95 delville with the 4.9. It has great power and all but when i drive it away from a stop sign while pulling away it is nice and quite and all is well with the world until i let up on the gas just slightly to maintain say 30mph.. while holding this speed it sounds like spark knock.. I use only premium gas in it so i know it is not a octaine issue but what about timing? i just bought this car in st louis and drove it to tampa florida(1000 miles) and had no other problems except the low oil pressure warning ( which i knew about allready) and it only does that when the oil gets hot and you stop and idle.. if you give it any gas at all the warning does not come on.. I think it is a pressure switch and i have bought a new one (ac delco) and will put in on and change the oil and filter and see if i still have that problem.
thanks in advance
wolfy
aka Roy



Take the air cleaner off and hold the throttle blades wide open. Look down the bores with a strong light. See the two tubes sticking up at you from the floor of the intake manifold beneatht the throttle plates..??? They should be clean and free of carbon...not full of crud and stopped up. Rod them out with a piece of stiff wire until they are clean. The part throttle detonation will stop. Those tubes are called the EGR tubes and there is lots on them and cleaning them in the archives if you search using "EGR tubes".

thank you so much will do as soon as i get home.
roy