I’m posting this again, and thanking those who’ve stuck with me since I feel bad, I didn’t give a lot of detail last time. I have a 1999 Ford Escort Zx2 2.0 Liter. It is not Leaking or burning oil, coolant level stays the same. I check the oil every few days, However, I will start it up in the AM and it sounds like a knocking or repeated whacking a dime or penny on a wooden table. The sound practically goes away within about 2 minutes after I drive or if I let the car warm up. I experimented with it tonight, by parking between two vans as it was warmed up and the sound is still very faintly there when it’s warmed up. The repetitions of the knockings do increase as I rev my engine I thought they stayed the same but I was wrong. I’m almost positive that it’s due for a tune up. And I am bringing her in for an oil change tomorrow. I also bought this detergent to clean the engine right before I get the oil changed. The car does run a little rough, but sometimes it surges up to 2k rpms right after I start it and sometimes it takes a few seconds for the car to turnover when I start it. Also, it’s kind of getting crappy gas mileage in accordance to what it should be gettiing. I guess my question is, what are your thoughts about what could be wrong with it? And is it time to get a home equity loan?
Also, High Octane Fuel will not in anyway quiet, kill, or muffle this noise.
Also, I used something called “Gunk Engine Flush” before today’s oil change, the engine is much, much quieter now, but I haven’t run it fully cold. Thoughts?
sounds like to me you have a fuel injector leaking when your car sits. the combustion chamber is fiiling up with fuel when it sits and running rich when you first start the car. cauing it to spark knock making that noise. this could cause worse fuel econemy and hard starts.
Well, I am getting tests done next week. I hope it’s something nice and cheap since I just bought this car. 
One thing NOT mentioned is a Exhaust manifold gasket leak. It sounds exactly like the sound you’re getting…and it usually goes away after a few minutes (or just gets a lot quieter).