Electronic Engine Control System: Other Mercury Montego III

Electronic Engine Controls

The electronic engine controls consist of the following

1. Power control module (PCM)
2. Engine coolant temperature (ECT) sensor
3. Camshaft position (CMP) sensor
4. Fuel rail pressure and temperature sensor
5. Crankshaft position (CKP) sensor
6. Mass air flow (MAF) sensor
7. Heated oxygen sensor (HO2S)
8. Catalyst monitor sensor
9. Knock sensor (KS)

The PCM

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

The ECT sensor

1. sends the PCM a signal indicating engine 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 fuel rail pressure and temperature sensor

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

The CKP sensor

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

The MAF sensor

1. uses a hot wire sensing element to measure the amount of air entering the engine. Air passing over the hot wire causes it to cool.

The HO2S

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

The catalyst monitor sensor

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

The KS

1. is used to detect engine detonation (spark knock).
2. sends a voltage signal to the PCM which retards the ignition timing as necessary.

Refer to the INTRODUCTION - GASOLINE article .

Scheme 9

Material

MATERIAL CHART

Scheme 10

1. Release the fuel system pressure. For additional information, refer to «FUEL SYSTEM-GENERAL INFORMATION»(ref-233044) .
2. Disconnect the battery ground cable. For additional information, refer to «BATTERY, MOUNTING AND CABLES»(ref-233036) .
3. Disconnect the fuel rail pressure and temperature sensor electrical connector.
4. Disconnect the fuel rail pressure and temperature sensor vacuum connector.
5. Remove the 2 bolts and the fuel rail pressure and temperature sensor. To install, tighten to 3 Nm (27 lb-in).
6. To install, reverse the removal procedure. Lubricate the O-ring seal with clean engine oil.

MATERIAL CHART

Scheme 11

1. Drain the engine cooling system. For additional information, refer to «ENGINE COOLING»(ref-233003) .
2. Disconnect the positive crankcase ventilation (PCV) and brake aspirator tubes from the air cleaner outlet pipe.
3. Disconnect the mass air flow (MAF) sensor electrical connector.
4. Loosen the air cleaner outlet tube clamp at the electronic throttle body. To install, tighten to 5 Nm (44 lb-in).
5. Remove the air cleaner housing cover and outlet tube assembly.
6. Disconnect the engine coolant temperature (ECT) sensor electrical connector.
7. Remove the hairpin clip and the ECT sensor.
8. To install, reverse the removal procedure. Use the alignment notches to correctly align the air cleaner housing cover to the air cleaner tray. Lubricate the O-ring seal with clean engine coolant.

Scheme 12

MATERIAL CHART

Scheme 13

1. With vehicle in NEUTRAL, position it on a hoist. For additional information, refer to «JACKING & LIFTING»(ref-232992) .
2. Disconnect the battery ground cable. For additional information, refer to «BATTERY, MOUNTING AND CABLES»(ref-233036) .
3. Disconnect the heated oxygen sensor (HO2S) electrical connector.
4. Remove the HO2S from the exhaust manifold using the special tool and discard. To install, tighten to 48 Nm (35 lb-ft).
5. To install, reverse the removal procedure. Apply a light coat of anti-seize lubricant to the threads of the HO2S.

MATERIAL CHART