Thump sound from engine while driving

Ive been driving my car. A 2000 Ford Contour and I was getting low on oil so I threw a quart in to tide me over to payday so I can get the oil changed. Now as Im driving I have times where I get little to no power followed by a loud single thump from my engine. It also sputters if I don’t put the gas down. Today after getting home I had to floor it to get up a hill and when I got to my house i saw a little bit of smoke or steam coming from the engine. What can this be?

I’m just going to say.

Look for replacement vehicle.


How low was the oil level?
After you added that quart, was the level on the dipstick at the “full” mark?
If not, how much lower was it?
And, how long was it been–in terms of both odometer mileage and elapsed time–since the last oil change?

Is the Check Engine light lit up?

Or–much worse, is the CEL flashing/blinking?

Is this car up-to-date with ALL of the vehicle mfr’s maintenance items?
I ask because I suspect that it has been…too long…between maintenance procedures, such as changing the spark plugs.

Was it actually smoke, or was it steam?
This does make a difference.
Have you checked the level of coolant in the radiator, after the engine was totally cooled-down?


Low power often means a fuel system, ignition system, or compression problem. No idea what the thump sound is tho. It could be a backfire sound effect from the engine missing and raw gasoline going into the exhaust system and igniting there I suppose. If I had this problem first thing I’d do is bring all the routine engine maintenance up to date, then check for a good healthy blue-white spark at the spark plugs during cranking. Compression check after that probably.