Electronic Engine Control System: Other Mercury Monterey VIII

Electronic Engine Controls

The electronic engine controls consist of the following

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. mass air flow (MAF) sensor
8. heated oxygen sensor (HO2S)
9. catalyst monitor sensor
10. vehicle speed sensor (VSS)
11. intake manifold runner control (IMRC)

The PCM needs the following inputs to calibrate the engine correctly

1. crankshaft position
2. intake air temperature
3. engine load (manifold pressure)
4. engine RPM
5. engine coolant temperature
6. camshaft position

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.
2. 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. sends the PCM a signal indicating camshaft position used for fuel synchronization.

The CKP sensor

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

The MAF sensor

1. sends the PCM a signal indicating the rate of mass air flow into the engine.

The IAT sensor

1. sends the PCM a signal indicating the temperature of the air entering the engine.
2. resistance decreases as temperature increases.

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 sensors

1. monitor oxygen content after it flows through the catalytic converter.
2. provides a voltage to the PCM used to calculate catalytic converter integrity.

The VSS

1. sends a signal to the PCM indicating wheel speed. For additional information, refer to «AUTOMATIC TRANSAXLE/TRANSMISSION»(ref-234499) .

The air induction system improves engine performance by using the IMRC assemblies as follows

1. The lower intake manifold has 2 runners per cylinder, feeding each of the intake ports in the cylinder heads.
2. The IMRC assemblies are located between the upper intake manifold and cylinder heads, providing 2 air passages for each cylinder.
3. One air passage is always open and the other passage switches from closed to open by means of a valve plate. Below 1,500 RPM, this valve plate is closed to improve fuel economy and emissions. Above 1,500 RPM, this valve plate opens to improve high speed engine performance.

The valve plates are opened and closed by the IMRC electric actuator, which is controlled by the PCM.

See INTRODUCTION - GASOLINE article.

Scheme 14

For additional information, refer to the component removal and installation procedures.

Material

MATERIAL SPECIFICATION

Scheme 15

1. Disconnect the battery ground cable. For additional information, refer to «BATTERY, MOUNTING AND CABLES»(ref-234519) .
2. Drain the cooling system. For additional information, refer to «ENGINE COOLING»(ref-234494) .
3. Disconnect the camshaft position sensor (CMP) electrical connector.
4. Remove the CMP sensor bolts and the CMP sensor.
5. Disconnect the coolant bypass hose from the coolant pump outlet tube.
6. Remove the 2 coolant pump outlet tube bolts and position aside the coolant outlet tube.
7. Remove the accessory drive belt. Rotate the accessory drive belt tensioner counterclockwise. Push the spring clip toward the belt tensioner to lock the accessory drive belt tensioner in place.
8. Remove the 4 power steering pump bolts and position aside the power steering pump.
9. Rotate the crankshaft until the No. 1 cylinder is at top dead center (TDC) of the compression stroke.
10. Remove the camshaft synchronizer-to-engine front cover bolt.
11. Remove the camshaft synchronizer. The oil pump driveshaft might not come out with the camshaft synchronizer. If so, retrieve the oil pump driveshaft before proceeding.

MATERIAL SPECIFICATION

Scheme 16

1. With the vehicle in NEUTRAL, position it on a hoist. For additional information, refer to «JACKING & LIFTING»(ref-234483) .
2. Disconnect the battery ground cable. For additional information, refer to «BATTERY, MOUNTING AND CABLES»(ref-234519) .
3. Disconnect the heated oxygen sensor (HO2S) electrical connector.
4. Using the special tool, remove the HO2S sensor. To install, tighten to 46 Nm (34 lb-ft).
5. To install, reverse the removal procedure.

MATERIAL SPECIFICATION

MATERIAL SPECIFICATION

Scheme 17