1999 LAND ROVER DISCOVERY air filter

EMISSION CONTROL - V8
DESCRIPTION AND OPERATION 17-2-27
The ECM connector and pins pertinent for secondary air injection are listed in the following table:
Secondary Air Injection System Components
The secondary air injection (SAI) system components (where fitted) are described below:
Secondary Air Injection (SAI) Pump
1SAI pump cover
2Foam filter3SAI pump
4Pressurised air to exhaust manifolds
The SAI pump is attached to a bracket at the rear RH side of the engine compartment and is fixed to the bracket by
three studs and nuts. The pump is electrically powered from a 12V battery supply via a dedicated relay and supplies
approximately 35kg/hr of air when the vehicle is at idle in Neutral/Park on a start from 20°C (68°F).
Air is drawn into the pump through vents in its front cover and is then passed through a foam filter to remove
particulates before air injection. The air is delivered to the exhaust manifold on each side of the engine through a
combination of plastic and metal pipes.
Connector / Pin No. Description Signal type Control
C0635-23 Main relay output Output drive Switch to ground
C0636-4 Secondary air injection vacuum solenoid
valve controlOutput, drive Switch to ground
C0636-16 Secondary air injection pump relay control Output drive Switch to ground
C0636-21 Coolant temperature (ECT) sensor Ground 0V
C0636-22 Coolant temperature (ECT) sensor Input signal Analogue 0 - 5V
C0637-20 MIL "ON" Output drive Switch to ground
M17 0204
1
4
2
3

EMISSION CONTROL - V8
17-2-28 DESCRIPTION AND OPERATION
The air delivery pipe is a flexible plastic type, and is connected to the air pump outlet via a plastic quick-fit connector.
The other end of the flexible plastic pipe connects to the fixed metal pipework via a short rubber hose. The part of the
flexible plastic pipe which is most vulnerable to engine generated heat is protected by heat reflective sleeving. The
metal delivery pipe has a fabricated T-piece included where the pressurised air is split for delivery to each exhaust
manifold via the SAI control valves.
The pipes from the T-piece to each of the SAI control valves are approximately the same length, so that the pressure
and mass of the air delivered to each bank will be equal. The ends of the pipes are connected to the inlet port of each
SAI control valve through short rubber hose connections.
The T-piece is mounted at the rear of the engine (by the ignition coils) and features a welded mounting bracket which
is fixed to the engine by two studs and nuts.
The foam filter in the air intake of the SAI pump provides noise reduction and protects the pump from damage due to
particulate contamination. In addition, the pump is fitted on rubber mountings to help prevent noise which is generated
by pump operation from being transmitted through the vehicle body into the passenger compartment.
If the secondary air injection (SAI) pump is found to be malfunctioning, the following fault codes may be stored in the
ECM diagnostic memory, which can be retrieved using Testbook/T4:
NOTE: Refer to 'SAI System Fault Finding' and 'Checking Malfunctions on SAI System' at the end of this section to
determine root cause of fault codes.
NOTE: The electrical test of the SAI pump powerstage only indicates that there is a problem with the relay or the
power supply to the relay. It does not indicate the state of the SAI pump itself (i.e. broken or not connected).
As a result of a SAI pump powerstage malfunction, other fault codes may also become stored in the ECM memory.
These may include the following P codes.
NOTE: A malfunction of the SAI pump powerstage is logically expected to result in both engine banks reporting the
same fault.
NOTE: Refer to 'SAI System Fault Finding' and 'Checking Malfunctions on SAI System' at the end of this section to
determine root cause of fault codes.
Secondary Air Injection (SAI) Pump Relay
The secondary air injection pump relay is located in the engine compartment fusebox. The engine control module
(ECM) is used to control the operation of the SAI pump via the SAI pump relay. Power to the coil of the relay is supplied
from the vehicle battery via the main relay and the ground connection to the coil is via the ECM.
Power to the SAI pump relay contacts is via fusible link FL2 which is located in the engine compartment fusebox.
P-code Description
P0418Secondary Air Injection System – Relay 'A' circuit malfunction (SAI pump
powerstage fault, e.g. - SAI pump relay fault or relay not connected / open circuit /
harness damage).
P-code Description
P1412Secondary Air Injection System – Malfunction Bank 1 LH (Insufficient SAI flow
during passive test)
P1414Secondary Air Injection System – Low air flow Bank 1 LH (Insufficient SAI flow
during active test)
P1415Secondary Air Injection System – Malfunction Bank 2 RH (Insufficient SAI flow
during passive test)
P1417Secondary Air Injection System – Low air flow Bank 2 RH (Insufficient SAI flow
during active test)

EMISSION CONTROL - V8
17-2-34 DESCRIPTION AND OPERATION
Crankcase Emission Control Operation
Oil laden noxious gas in the engine crankcase is drawn through a spiral oil separator located in the stub pipe to the
ventilation hose on the right hand cylinder head rocker cover, where oil is separated and returned to the cylinder head.
The rubber ventilation hose from the right hand rocker cover is routed to a port on the right hand side of the inlet
manifold plenum chamber, where the returned gases mix with the fresh inlet air passing through the throttle butterfly
valve. The stub pipe on the left hand rocker cover does not contain an oil separator, and the ventilation hose is routed
to the throttle body housing at the air inlet side of the butterfly valve. The mass of fresh air which is drawn in from the
atmospheric side of the throttle butterfly to mix with the returned crankcase gas depends on the throttle position and
the engine speed.
1Hose – RH rocker cover to inlet manifold
2Inlet manifold
3Throttle body
4Air intake
5Hose – LH rocker cover to inlet manifold
6LH rocker cover breather tube
(without oil separator)7LH rocker cover baffle
8RH rocker cover baffle
9RH rocker cover breather tube
10Oil separator (integral with breather tube)
When the engine is running in cruise conditions or at idle, manifold pressure is low and the majority of gases are drawn
into the inlet manifold through the oil / vapour separator in the RH rocker cover stub pipe. At the same time, filtered
air is drawn from the throttle body into the engine via the LH rocker cover.
During periods of driving at Wide Open Throttle (WOT), pressure at either side of the throttle disc equalizes (manifold
depression collapses). The larger ventilation opening at the throttle housing positioned in the fast moving stream of
intake air, now offers more 'pull' than the small opening in the RH rocker cover and the flow of ventilation reverses,
drawing gases from the LH rocker cover into the throttle body for subsequent burning in the combustion chambers.

EMISSION CONTROL - V8
17-2-38 DESCRIPTION AND OPERATION
Mass Air Flow (MAF) Sensor and Air Temperature Sensor
The engine management ECM uses the mass air flow sensor to measure the mass of air entering the intake and
interprets the data to determine the precise fuel quantity which needs to be injected to maintain the stoichiometric
air:fuel ratio for the exhaust catalysts. If the mass air flow sensor fails, lambda control and idle speed control will be
affected and the emission levels will not be maintained at the optimum level. If the device should fail and the ECM
detects a fault, it invokes a software backup strategy.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
The air temperature sensor is used by the engine management ECM to monitor the temperature of the inlet air. If the
device fails, catalyst monitoring will be affected. The air temperature sensor in integral to the mass air flow sensor.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
Throttle Position Sensor
If the engine management ECM detects a throttle position sensor failure, it may indicate a blocked or restricted air
intake filter. Failure symptoms may include:
lPoor engine running and throttle response
lEmission control failure
lNo closed loop idle speed control
lAltitude adaption is incorrect
If a signal failure should occur, a default value is derived using data from the engine load and speed.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
Atmospheric pressure will vary with altitude and have a resulting influence on the calculations performed by the ECM
in determining the optimum engine operating conditions to minimise emissions. The following are approximate
atmospheric pressures for the corresponding altitudes:
l0.96 bar at sea level
l0.70 bar at 2,750 m (9,000 ft.)

EMISSION CONTROL - V8
17-2-42 DESCRIPTION AND OPERATION
If the piping is broken forward of the purge valve or is not connected, the engine may run rough and fuelling adaptions
will drift. The fault will not be detected by the leak detection diagnostic, but it will be determined by the engine
management ECM through the fuelling adaption diagnostics.
The evaluation of leakage is dependent on the differential pressure between the fuel tank and ambient atmospheric
pressure, the diagnostic is disabled above altitudes of 9500 ft. (2800 m) to avoid false detection of fuel leaks due to
the change in atmospheric pressure at altitude.
Fuel Leak Detection System Operation (positive pressure leak detection type) – NAS only
The EVAP system with positive pressure leak detection capability used on NAS vehicles is similar to the standard
system, but also includes a fuel evaporation leak detection pump with integral solenoid valve. It is capable of detecting
holes in the EVAP system down to 0.5 mm (0.02 in.). The test is carried out at the end of a drive cycle, when the
vehicle is stationary and the ignition switch has been turned off. The ECM maintains an earth supply to the Main relay
to hold it on, so that power can be supplied to the leak detection pump.
First a reference measurement is established by passing the pressurised air through a by-pass circuit containing a
fixed sized restriction. The restriction assimilates a 0.5 mm (0.02 in) hole and the current drawn by the pump motor
during this procedure is recorded for comparison against the value to be obtained in the system test. The purge valve
is held closed, and the reversing valve in the leak detection pump module is not energised while the leak detection
pump is switched on. The pressurised air from the leak detection pump is forced through an orifice while the current
drawn by the pump motor is monitored.
Next the EVAP system diagnostic is performed; the solenoid valve is energised so that it closes off the EVAP system's
vent line to atmosphere, and opens a path for the pressurised air from the leak detection pump to be applied to the
closed EVAP system.
The current drawn by the leak detection pump is monitored and checked against that obtained during the reference
measurement. If the current is less than the reference value, this infers there is a hole in the EVAP system greater
than 0.5 mm (0.02 in) which is allowing the positive air pressure to leak out. If the current drawn by the pump motor
is greater than the value obtained during the reference check, the system is sealed and free from leaks. If an EVAP
system leak is detected, the ECM stores the fault in diagnostic memory and the MIL light on the instrument pack is
illuminated.
On NAS vehicles, the ECM works on a 2 trip cycle before illuminating the MIL. On EU-3 vehicles, the ECM works on
a 3 trip cycle before illuminating the MIL.
Following the test, the solenoid valve is opened to normalise the EVAP system pressure and the system returns to
normal purge operation at the start of the next drive cycle. Possible reasons for an EVAP system leak test failure are
listed below:
lFuel filler not tightened or cap missing.
lSensor or actuator open circuit.
lShort circuit to vehicle supply or ground.
lEither purge or solenoid valve stuck open.
lEither purge or solenoid valve stuck shut.
lBlocked pipe or air filter.
lPiping broken or not connected.
lLoose or leaking connection.
If the piping is broken forward of the purge valve or is not connected, the engine may run rough and fuelling adaptions
will drift. The fault will not be detected by the leak detection test, but will be determined by the engine management
ECM through the fuelling adaption diagnostics. This test can be run from TestBook/T4.

EMISSION CONTROL - V8
REPAIRS 17-2-53
Canister - EVAP - Models with Fuel Leak
Detection Pump - from 03MY
$% 17.15.13
Remove
1.Raise the vehicle on lift.
2.Disconnect multiplug from the fuel leak
detection pump.
3.Disconnect the fuel leak detection filter pipe
from the fuel leak detection pump.
4.Release clips and disconnect 2 vent pipes from
the EVAP canister.
CAUTION: Always fit plugs to open
connections to prevent contamination.5.Remove and discard 4 bolts securing EVAP
canister mounting bracket to the chassis and
remove the EVAP canister assembly.
NOTE: Do not carry out further dismantling if
component is removed for access only.
6.Remove bolt securing EVAP canister retaining
clamp to the mounting bracket and collect the
clamp.
7.Remove nut and bolt securing EVAP canister to
the mounting bracket.

EMISSION CONTROL - V8
17-2-54 REPAIRS
8.Remove and discard clip securing fuel leak
detection pump fuel pipe to the EVAP canister
and disconnect the fuel pipe.
9.Remove the EVAP canister.
Refit
1.Position EVAP canister to the mounting
bracket.
2.Connect fuel leak detection pump fuel pipe to
the EVAP canister and secure with a new clip.
3.Fit nut and bolt securing EVAP canister to the
mounting bracket and tighten to 10 Nm (7 lbf.ft).
4.Position EVAP canister retaining clamp to the
mounting bracket, fit bolt and tighten to 10 Nm
(7 lbf.ft).
5.Position EVAP canister mounting bracket to the
chassis, fit new bolts and tighten to 25 Nm (18
lbf.ft).
6.Connect vent pipes to the EVAP canister.
7.Connect multiplug to the fuel leak detection
pump.
8.Connect the fuel leak detection filter pipe to the
fuel leak detection pump.
9.Lower the vehicle lift.
Valve - purge control
$% 17.15.39
Remove
1.Disconnect multiplug from purge control valve.
2.Release clips securing hoses to purge control
valve.
3.Disconnect hoses from purge control valve and
remove valve.
CAUTION: Always fit plugs to open
connections to prevent contamination.
Refit
1.Position purge control valve and connect
hoses.
2.Fit clips to secure hoses to purge control valve.
3.Connect multiplug to purge control valve.

EMISSION CONTROL - V8
17-2-64 REPAIRS
Pump - Fuel Leak Detection - up to 03MY
$% 17.45.41
Remove
1.Raise the vehicle on lift.
2.Disconnect multiplug from fuel leak detection
pump.
3.Release leak detection air filter hose from top of
pump.
4.Remove 3 Torx screws securing pump to
mounting bracket.
5.Remove clip securing EVAP canister hose to
pump.
6.Release EVAP canister hose from pump.
7.Remove pump.
Refit
1.Connect EVAP canister hose to pump and
secure with clip.
2.Position pump to mounting bracket and secure
with Torx screws.
3.Connect leak detection air filter hose to top of
leak detection pump.
4.Connect multiplug to pump.
5.Lower vehicle.
Pump - fuel leak detection - from 03MY
$% 17.45.41
Remove
1.Raise the vehicle on lift.
2.Disconnect multiplug from the fuel leak
detection pump.
3.Remove 3 screws securing the fuel leak
detection pump to the chassis mounting
bracket.
4.Position absorbent cloth around fuel hoses to
collect any fuel spillage.
5.Disconnect the fuel leak detection filter pipe
from the fuel leak detection pump.
CAUTION: Always fit plugs to open
connections to prevent contamination.
6.Remove and discard clip securing EVAP pipe
to the fuel leak detection pump and disconnect
the pipe.
7.Remove the fuel leak detection pump.
Refit
1.Connect the EVAP pipe to the fuel leak
detection pump and secure with a new clip.
2.Connect the fuel leak detection filter pipe to the
fuel leak detection pump.
3.Remove absorbent cloth.
4.Fit and tighten 3 screws securing the fuel leak
detection pump to the chassis mounting
bracket.
5.Connect multiplug to the fuel leak detection
pump.
6.Lower the vehicle lift.
M17 0235
2
3
4
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