Removal & Installation - Ford Ranger Maintaince And Repair Manual

REMOVAL & INSTALLATION
Ford recommends replacing standard spark plugs every 30,000 miles (48,000km) and platinum plugs
every 60,000 miles (96,000km).
A set of spark plugs usually requires replacement after about 20,000−30,000 miles (32,000−48,000km),
depending on your style of driving. In normal operation plug gap increases about 0.001 in. (0.025mm) for
every 2500 miles (4000km). As the gap increases, the plug's voltage requirement also increases. It requires a
greater voltage to jump the wider gap and about two to three times as much voltage to fire the plug at high
speeds than at idle. The improved air/fuel ratio control of modern fuel injection combined with the higher
voltage output of modern ignition systems will often allow an engine to run significantly longer on a set of
standard spark plugs, but keep in mind that efficiency will drop as the gap widens (along with fuel economy
and power).
When you're removing spark plugs, work on one at a time. Don't start by removing the plug wires all at once,
because, unless you number them, they may become mixed up. Take a minute before you begin and number
the wires with tape. Also, an anti−seize compound should be used before installing the plugs into the cylinder
head.
1. Disconnect the negative battery cable, and if the vehicle has been run recently, allow the engine to
thoroughly cool.
2. Carefully twist the spark plug wire boot to loosen it, then pull upward and remove the boot from the
plug. Be sure to pull on the boot and not on the wire, otherwise the connector located inside the boot
may become separated.
80
HOW TO USE THIS BOOK
Always twist and pull on the spark plug boot, never on the wire
REMOVAL & INSTALLATION