Land Rover Bosch 5 2 1 Engine Management Systems Rover Manual

BOSCH 5.2.1 ENGINE MANAGEMENT SYSTEM
Bosch 5.2.1 Engine Management System 157 Idle speed actuator
The idle speed control actuator is located behind the throttle body on the intake manifold. It is 
connected to the intake manifold by two hoses. One hose connects upstream and the other 
connects downstream of the throttle valve. Therefore, the idle speed actuator effect provides an 
air bypass for the throttle valve.
The ECM controls the engine idle speed via the idle speed actuator. It does this by...

BOSCH 5.2.1 ENGINE MANAGEMENT SYSTEM
158 For 20 seconds immediately following cold start, the idle speed will be raised to 1200 rpm. At 
the same time the ECM will retard the ignition timing. These actions ensure the engine and the 
catalysts reach their operating temperatures as quickly as possible.
The ECM can identify faults with the circuitry used to control the position of the idle speed 
actuator. In circumstances where it detects a fault with one coil it will de-energise the other coil. 
This...

BOSCH 5.2.1 ENGINE MANAGEMENT SYSTEM
Bosch 5.2.1 Engine Management System 159 The ECM controls its own power supply, via the main relay. When the ignition is turned to 
position II, the ECM provides a ground to the relay coil winding. This, in turn, connects the main 
power feed to the ECM. The ECM controls the main relay and therefore its own power, so that 
when the ignition is turned off it can follow the previously described power-down sequence, 
during which it records values from various sensors...

BOSCH 5.2.1 ENGINE MANAGEMENT SYSTEM
160brake drum
•  The fuel tank pressure sensor, located in the fuel sender unit
•  The intake manifold
The ECM controls the amount of vapor drawn from the charcoal canister by controlling the 
length of time the purge valve is open. It controls the length of time it is open by supplying the 
purge valve with a PWM voltage. Control is used to maintain the required level of emissions, as 
a hydrocarbon vapor level of 1% can affect the air/fuel ratio by as much as 20%....

BOSCH 5.2.1 ENGINE MANAGEMENT SYSTEM
Bosch 5.2.1 Engine Management System 161 ECM Adaptations
The ECM, as previously mentioned, has the ability to adapt the values it uses to control certain 
outputs. This capability ensures the EMS can meet emissions legislation and improve the 
refinement of the engine throughout its operating range.
The components which have adaptations associated with them are:
•  The idle speed control (ISC) valve 
•  The throttle position sensor (TPS)
•  The Heated Oxygen sensors...

BOSCH 5.2.1 ENGINE MANAGEMENT SYSTEM
162 The ECM will store a fault code in circumstances where an adaptation is forced to exceed its 
operating parameters. At the same time, the ECM will record the engine speed, engine load and 
intake air temperature.
Crankshaft position sensor
The characteristics of the signal supplied by the crankshaft position sensor are learned by the 
ECM. This enables the ECM to set an adaptation and support the engine misfire detection 
function. Due to the small variation...

BOSCH 5.2.1 ENGINE MANAGEMENT SYSTEM
Bosch 5.2.1 Engine Management System 163 Misfire detection
Legislation requires that the ECM must be able to detect the presence of an engine misfire. It 
must be able to detect misfires at two separate levels. The first level is a misfire that could lead 
to the vehicle emissions exceeding 1.5 times the allowable levels for this engine. The second 
level is a misfire that may cause catalyst damage.
The ECM monitors the number of misfire occurrences within two engine...

BOSCH 5.2.1 ENGINE MANAGEMENT SYSTEM
164 TestBook Diagnostics
The ECM will, as explained earlier, store fault codes and environmental data. The ECM also 
records additional data in connection with each fault. The additional data recorded is as follows:
1  The number of occurrences
2  If the fault is currently present
3  If the fault is historic, the number of ‘journeys’ that have elapsed since the fault last 
occurred.
4  The ‘current time’ stored when the fault occurred. (The time is incremented in...

BOSCH 5.2.1 ENGINE MANAGEMENT SYSTEM
Bosch 5.2.1 Engine Management System 165 Connector Pinouts
Bosch 5.2.1
Connector 1
C0634 (9-way, Black)
PIN Wire
ColorDescription Voltage Reading
1 W Ignition sense (position II) 12 V
2-
3-
4 B Chassis Earth 0V
5 B Fuel Injectors Earth 0V
6 B Power stage Earth 0V
7 PY Permanent Battery supply 12 V
8 NO Switched Relay positive 0-12V
9- 

BOSCH 5.2.1 ENGINE MANAGEMENT SYSTEM
166 Connector 2
C0635 (24-way, Black)
PIN Wire
ColorDescription Signal
RangePIN Wire
ColorDescription Signal
Range
1 WU HO2S Heater Bank B -
downstream12-0V 13 WO HO2S Heater Bank B -up-
stream12-0V  
2 - 14 G HO2S signal Bank B-down-
stream0-1V  
3 - 15 O HO2S signal Bank A -up-
stream0-1V  
4 - 16 U HO2S signal Bank B -up-
stream0-1V  
5 Thermostat Monitoring
Thermistor Ground 0V 17 Y HO2S signal Bank A -
downstream0-1V  
6 - 18 UP Fuel pump relay [PWM] 12-0V
7 WU...