I just inherited my grandmothers 1993 Cavalier 2.2L Sedan, and it hadn't been driven in some time. So I changed the oil in and got it started up without much trouble, and noticed all the way home it was rattling or pinging under load. I thought it was valves or rod knock at first.

When I got home and was messing around with it, I unplugged the spark plug wires one at a time while it was running and revved it to see if the noise was gone, and on cylinder number 4 (closest to the EGR valve) the noise is gone completey when the fuel injector or plug wire disconnected.

How can only one cylinder be pinging. The car drives great with execellent power, any ideas?

 

Am I going in the right direction thinking this could possibly be a clogged EGR valve, would it affect the cylinder closest to it? I haven't pulled it off yet to check, but the cylinder right there is the one that pings. Going to take it off when I get home today.