engine runs rough on 2003 Ford Focus

When the car is started and is still cold, the car sounds loud, its sounds like its running rough but it doesnt run rough just sounds louder than normal. It almost sounds like theres a hole in the exhaust or the muffler is bad. I cant tell

Asked by for the 2003 Ford Focus
Some cars have an electric air pump for the emissions system. This pump only runs when the engine is warming up, and the pump can be quite loud. You may also have an exhaust leak that get's quieter as the engine warms up.
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ok this is very simple, change the coil .remember the Ford Focus on 2001 doesnt have an ignition box, just a coil box that is located on the left side of the engine ( right if you standing in front of the car) close to the battery. the coil box goes bad after a lot of years of use, can be burned under or with black stains signal of malfuntion). pull it out ( only 4 screws) unplug the wire and replace for a new one (cost around 90 to 132 dollars) but for easy change... take the old coil and spark plugs wires out of the engine but never take off the ones in the old coil, that way you can follow the installation order in the new coil. what i always do after the coil is been replace and the connected, i change the spark plugs ( split fire or similar), new wires and clear the engine light .make sure the cables are well conected in the firing older (1324) in the engine ( Zetec)..... you will ride in a smooth ford focus no matter the year. i hope this info helps others with the same problem. *****by Freddie Rios.