Discovery 2. Manual - part 76

 

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Discovery 2. Manual - part 76

 

 

ENGINE MANAGEMENT SYSTEM - V8

DESCRIPTION AND OPERATION 18-2-33

Fuel injectors

The fuel injectors are located beneath the air inlet manifold. They utilise an electrical solenoid to lift the injector needle 
off its seat to allow fuel injection to take place. The fuel injectors provide excellent fuel atomisation in the lower portion 
of the inlet manifold, the air/fuel mixture can then be drawn into the cylinders to give good combustion characteristics 
and therefore excellent driveability.

There are eight fuel injectors one per cylinder that the ECM operates sequentially. All the injectors are fed from a 
common fuel rail as part of the returnless fuel system. Fuel pressure is maintained at a constant 3.5 bar (52 lbf.in

2

) by 

a regulator that is integral with the fuel pump.
 

 + 

 FUEL DELIVERY SYSTEM - V8, DESCRIPTION AND OPERATION, Description.

Input/Output
All eight fuel injectors are supplied with battery voltage via fuse number 1 located in engine compartment fuse box. 
The ECM controls the individual earth path for each injector via its own pin at connector C0636 of the ECM multiplug. 
This facility allows the ECM to control the fuel injectors so that sequential fuel injection can take place. 

Typical hot engine injector pulse width values:

l

Idle = 2.5 ms.

l

Peak torque (3000 rev/min) = 7 ms The ECM controls injector earth as follows:

l

Cylinder No 1 - pin 41 of connector C0636 of the ECM multiplug.

l

Cylinder No 2 - pin 1 of connector C0636 of the ECM multiplug.

l

Cylinder No 3 - pin 27 of connector C0636 of the ECM multiplug.

l

Cylinder No 4 - pin 40 of connector C0636 of the ECM multiplug.

l

Cylinder No 5 - pin 2 of connector  C0636 of the ECM multiplug.

l

Cylinder No 6 - pin 15 of connector C0636 of the ECM multiplug.

l

Cylinder No 7 - pin 14 of connector C0636 of the ECM multiplug.

l

Cylinder No 8 - pin 28 of connector C0636 of the ECM multiplug.

Individual injectors can be measured for resistance using a multimeter. An acceptable injector resistance is as follows:

l

14.5  

±

 0.7 ohms at 20 

°

C (68 

°

F).

The fuel injectors can fail in the following ways or supply incorrect signal:

l

Injector actuator open circuit.

l

Short circuit to vehicle supply.

l

Short circuit to vehicle earth.

l

Blocked injector.

l

Restricted injector.

l

Low fuel pressure.

ENGINE MANAGEMENT SYSTEM - V8

18-2-34 DESCRIPTION AND OPERATION

In the event of fuel injector signal failure any of the following symptoms may be observed:

l

Rough running.

l

Difficult starting.

l

Engine misfire.

l

Possible catalyst damage.

l

High emissions.

l

Adaptive fuelling disabled.

l

Adaptive idle speed control disabled.

The ECM performs three types of fuel injector diagnostic check:

l

Output short circuit to earth

l

Output short circuit to battery voltage

l

Output open circuit

Should a malfunction of the component occur the following fault codes may be evident and can be retrieved by 
TestBook:

P Code

J2012 Description

Land Rover Description

P0201

Injection circuit malfunction - cylinder 1

Injector 1 open circuit

P0261

Cylinder 1 injector circuit low

Injector 1 short circuit to earth

P0262

Cylinder 1 injector circuit high

Injector 1 short circuit to battery supply

P0301

Cylinder 1 misfire detected

Injector 1 excess emissions/catalyst damaging level of 
misfire 

P0202

Injection circuit malfunction - cylinder 2

Injector 2 open circuit

P0264

Cylinder 2 injector circuit low

Injector 2 short circuit to earth

P0265

Cylinder 2 injector circuit high

Injector 2 short circuit to battery supply

P0302

Cylinder 2 misfire detected

Injector 2 excess emissions/catalyst damaging level of 
misfire

P0203

Injection circuit malfunction - cylinder 3

Injector 3 open circuit

P0267

Cylinder 3 injector circuit low

Injector 3 short circuit to earth

P0268

Cylinder 3 injector circuit high

Injector 3 short circuit to battery supply

P0303

Cylinder 3 misfire detected

Injector 3 excess emissions/catalyst damaging level of 
misfire

P0204

Injection circuit malfunction - cylinder 4

Injector 4 open circuit

P0270

Cylinder 4 injector circuit low

Injector 4 short circuit to earth

P0271

Cylinder 4 injector circuit high

Injector 4 short circuit to battery supply

P0304

Cylinder 4 misfire detected

Injector 4 excess emissions/catalyst damaging level of 
misfire 

P0205

Injection circuit malfunction - cylinder 5

Injector 5 open circuit

P0273

Cylinder 5 injector circuit low

Injector 5 short circuit to earth

P0274

Cylinder 5 injector circuit high

Injector 5 short circuit to battery supply

P0305

Cylinder 5 misfire detected

Injector 5 excess emissions/catalyst damaging level of 
misfire 

P0206

Injection circuit malfunction - cylinder 6

Injector 6 open circuit

P0276

Cylinder 6 injector circuit low

Injector 6 short circuit to earth

P0277

Cylinder 6 injector circuit high

Injector 6 short circuit to battery supply

P0306

Cylinder 6 misfire detected

Injector 6 excess emissions/catalyst damaging level of 
misfire

P0207

Injection circuit malfunction - cylinder 7

Injector 7 open circuit

P0279

Cylinder 7 injector circuit low

Injector 7 short circuit to earth

P0280

Cylinder 7 injector circuit high

Injector 7 short circuit to battery supply

P0307

Cylinder 7 misfire detected

Injector 7 excess emissions/catalyst damaging level of 
misfire

P0208

Injection circuit malfunction - cylinder 8

Injector 8 open circuit

P0282

Cylinder 8 injector circuit low

Injector 8 short circuit to earth

P0283

Cylinder 8 injector circuit high

Injector 8 short circuit to battery supply

ENGINE MANAGEMENT SYSTEM - V8

DESCRIPTION AND OPERATION 18-2-35

P0308

Cylinder 8 misfire detected

Injector 8 excess emissions/catalyst damaging level of 
misfire

P0171

System too lean (bank 1)

Multiplication injector adaptive fuelling - lean limit 
exceeded LH bank

P0172

System too rich (bank 1)

Multiplication injector adaptive fuelling - rich limit 
exceeded LH bank

P0174

System too lean (bank 2)

Multiplication injector adaptive fuelling - lean limit 
exceeded RH bank

P0175

System too rich (bank 2)

Multiplication injector adaptive fuelling - rich limit 
exceeded RH bank

P1171

System too lean (bank 1)

Additive injector adaptive fuelling - lean limit exceeded 
LH bank

P1172

System too rich (bank1)

Additive injector adaptive fuelling - rich limit exceeded 
LH bank

P1174

System too lean (bank 2)

Additive injector adaptive fuelling - lean limit exceeded 
RH bank

P1175

System too rich (bank 2)

Additive injector adaptive fuelling - rich limit exceeded 
RH bank

P0300

Random/multiple cylinder excess emissions 
detected

Excess emissions detected on more than one cylinder

P1300

Random/multiple cylinder misfire detected

Catalyst damaging level of misfire on more than one 
cylinder

P1319

Misfire detected with low fuel level

P Code

J2012 Description

Land Rover Description

ENGINE MANAGEMENT SYSTEM - V8

18-2-36 DESCRIPTION AND OPERATION

Idle Air Control Valve (IACV) (C0641)

The IACV is located on the side of the air inlet pipe on top of the engine. The IACV is used to maintain good quality 
idle speed under all operating conditions.

When an engine is running at idle it is subject to a combination of internal and external loads that can affect idle speed. 
These loads include engine friction, water pump, alternator operation, and air conditioning.

The IACV acts as an air bypass valve. The ECM uses the IACV to enable the closed loop idle speed calculation to be 
made by the ECM. This calculation regulates the amount of air flow into the engine at idle, therefore compensating 
for any internal or external loads that may affect idle speed.

The IACV utilises two coils that use opposing PWM signals to control the position of opening/closing of a rotary valve. 
If one of the circuits that supply the PWM signal fails, the ECM closes down the remaining signal preventing the IACV 
from working at its maximum/ minimum setting. If this should occur, the IACV automatically resumes a default idle 
position. In this condition, the engine idle speed is raised and maintained at 1200 rev/min with no load placed on the 
engine.

The idle speed in cold start condition is held at 1200 rev/min in neutral for 20 seconds and ignition timing is retarded 
as a catalyst heating strategy. The cold start idle speed and the default idle position give the same engine speed 1200 
rev/min, and although they are the same figure they must not be confused with each other as they are set separately 
by the ECM.

Note that the rotary valve must not be forced to move by mechanical means. The actuator can not be 
serviced; if defective, the entire IACV must be replaced.

Input/Output
The input to the IACV is a 12 volt signal from fuse 2 located in the engine compartment fuse box. The output earth 
signal to open and close the actuator is controlled by the ECM as follows:

l

IACV (open signal) - via pin 42 of connector C0636 of the ECM

l

IACV (closed signal) - via pin 43 of connector C0636 of the ECM

The IACV can fail the following ways or supply incorrect signal: 

l

Actuator faulty.

l

Rotary valve seized.

l

Wiring loom fault.

l

Connector fault.

l

Intake system air leak.

l

Blocked actuator port or hoses.

l

Restricted or crimped actuator port or hoses.

In the event of an IACV signal failure any of the following symptoms may be observed:

l

Either low or high idle speed.

l

Engine stalls.

l

Difficult starting.

l

Idle speed in default condition.

 

 

 

 

 

 

 

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