Electronic Engine Control System: Other Ford Focus I facelift

Electronic Engine Controls

The electronic engine controls consist of the

1. powertrain control module (PCM).
2. throttle position (TP) sensor.
3. idle air control (IAC) valve.
4. cylinder head temperature (CHT) sensor.
5. camshaft position (CMP) sensor.
6. crankshaft position (CKP) sensor.
7. power steering pressure (PSP) switch.
8. mass air flow (MAF) sensor.
9. heated oxygen sensor (HO2S).
10. catalyst monitor sensor(s).
11. knock sensor (KS).
12. fuel rail pressure and temperature sensor.

The PCM

1. accepts input from various engine sensors to compute the fuel flow rate and spark timing necessary to maintain a prescribed air/fuel ratio throughout the entire engine operating range.
2. outputs a command to the fuel injectors to meter the appropriate quantity of fuel.

The TP sensor

1. sends the PCM a signal indicating the throttle plate angle.
2. is the main input to the PCM from the driver.

The IAC valve

1. controls bypass air around the throttle plate at low engine speeds.
2. accommodates for small changes in engine load.
3. is controlled by the PCM.

The CHT sensor

1. sends the PCM a signal indicating cylinder head temperature.
2. resistance decreases as coolant temperature increases.

The CMP sensor

1. provides camshaft position information which is used by the PCM for fuel synchronization.

The CKP sensor

1. sends the PCM a signal indicating crankshaft position.
2. is essential for calculating spark timing.

The PSP switch

1. is a normally closed switch that opens as pressure increases.
2. is used to send a signal to the PCM to adjust idle speed. This compensates for additional load on the engine from the power steering pump.

The MAF sensor

1. uses a hot wire sensing element to measure the amount of air entering the engine.
2. uses a second hot wire to measure intake air temperature.
3. sends signals to the PCM. The PCM will then calculate the required fuel injector pulse width in order to provide the desired air/fuel ratio.

The HO2S

1. has the ability to create a voltage signal dependent on exhaust oxygen content.
2. provides feedback information to the PCM used to calculate fuel delivery.

The catalyst monitor sensor(s)

1. has the ability to create a voltage signal dependent on exhaust oxygen content.
2. provides feedback information to the PCM used to calculate catalyst efficiency.

The KS

1. sends a signal to the PCM indicating engine detonation, which retards the ignition timing as necessary.

The fuel rail pressure and temperature sensor

1. measures the pressure and temperature of the fuel rail and sends these signals to the PCM.
2. uses intake manifold vacuum as a pressure reference.

Refer to the Introduction - Gasoline Engines article.

Camshaft Position (CMP) Sensor

Material

Scheme 11

1. Disconnect the battery ground cable. For additional information, refer to «BATTERY, MOUNTING AND CABLES»(ref-278287) article.
2. Disconnect the camshaft position (CMP) sensor electrical connector.
3. Remove the bolt and the CMP sensor. To install, tighten to 20 Nm (15 lb-ft).
4. To install, reverse the removal procedure.

Crankshaft Position (CKP) Sensor

Special Tools Illustration Tool Name Tool Number Timing Peg, Crankshaft 303-507

Scheme 12

Scheme 13

1. With the vehicle in NEUTRAL, position it on a hoist. For additional information, refer to «JACKING AND LIFTING»(ref-278237) article.
2. Disconnect the battery ground cable. For additional information, refer to «BATTERY, MOUNTING AND CABLES»(ref-278287) article.
3. Remove the 2 retaining screws and the crankshaft pulley shield.
4. Disconnect the crankshaft position (CKP) sensor electrical connector.
5. Remove the engine front plug.
6. Turn the crankshaft pulley bolt to position the No. 1 cylinder at top dead center and install the special tool.
7. Remove the CKP sensor retaining bolts and the sensor.
8. Install a 6 mm x 18 mm standard bolt.

Heated Oxygen Sensor (HO2S)

Material

Catalyst Monitor Sensor

Material