How often do you need to tune up a 2002 Ford Focus se?

Answer 1

The US Model Ford Focus, 2000 through 2004 models, with a Z-Tech DOHC engine, uses a solid state ignition source so there are no points, rotors or distributor cap to wear out or replace. Ford recommends replacing the plugs at 100k miles. I would replace the plug wires then as well.

If your '00 through '04 Focus has less miles than that but you have experienced engine missing or backfiring, particularly after going to a car wash or a rainy day then I would recommend replacing the plug wires, and even the ignition coil unit. That is the unit that the plug wires connect to on one end; the other end being the spark plug. For those of us old guys it looks like an old distributor cap.

The ignition unit is sealed with the solid state components epoxied inside, but the epoxy can crack with age, so when the car goes through the car wash moisture can enter the coil and the result is an engine missing badly with a major power loss. Cracked wires can show similar symptoms.

At some point after 2004, I believe Ford changed to individual coils for the Focus. This means there are no plug wires at all, only each spark plug with an individual coil snapped right on top of it.