Lvangundy

When I start my car in the morning (about 50F outside) I let it idle for about 30-60secs and then slightly rev the engine up and keep it there for another 30-60 secs. Around the 1400-1600RPM range the engine makes a loud cracking noise like if someone was hitting the engine with a hammer really fast.

Any clues on that?

Another thing - What is the idle speed when dead cold and when warmed up idle? Arent't these 1200 and 600RPM repspectively?

Mine idles about 100RPM off from each of these. Could this be the idle/throttle screw or the idle sensor like David had a problem with?

JBrady

Lee, this could be anything from a cold exhaust leak (one that stops as the metal heats and expands) to a rod knock. If it is rod knock (bearing damage on the connecting rod allowing it to hammer back and forth) you are in a bad place. Hopefully it is something else. You should have it inspected by someone knowledgeable. Diagnosing "noises" remotely is very hard.