Powertrain

Engine Ignition

~1min read

The Electronic Ignition (EI) system is a coil-on-plug ignition system. The coil-on-plug ignition system consists of the:

  • Camshaft Position (CMP) sensor.
  • Crankshaft Position (CKP) sensor.
  • coil on plug.
  • spark plugs.

The CMP sensor:

  • is a Hall-effect sensor.
  • is mounted in the valve cover.
  • provides camshaft rotational location information to the PCM.

The CKP sensor:

  • is a variable reluctance sensor.
  • is mounted on the engine front cover.
  • is triggered by a 36-minus-1 tooth trigger wheel located on the crankshaft pulley and damper.
  • provides ignition timing and crankshaft speed (rpm) to the PCM.

The coil-on-plugs:

  • change low voltage signals from the PCM to high voltage pulses.
  • produce the high voltage pulses to the spark plugs.
  • are connected directly to each spark plug.
  • have replaceable coil boots.

The spark plug:

  • ignites the fuel and air mixture.

Test yourself

A quick Ford Focus quiz: every answer comes with an explanation and a link to the manual page.