warning JAGUAR XF 2009 1.G AJ133 5.0L Engine Manual

Technical Training
NP10-V8JLR: AJ133 5.0-Liter DFI V8 Engine 04/14/2009
3-7
Engine Management System

Overview

WARNINGS:
• Direct injection injectors require high booster voltages (65V); special care must be
taken to guarantee proper electrical isola-
tion of the cable harness and all connectors.
The ECM outputs for the injectors are pro-
tected in case of open and short circuit.
• Due to the high currents in the injectors, strong magnetic fields are created. An influ-
ence within a distance of up to 0.2m from
the wiring harness or control unit is to be
expected. Each vehicle type must therefore
be checked to ensure that this distance is
maintained. In particular, the interference-
free function of pacemakers cannot be
guaranteed.
CAUTIONS:
• DO NOT connect test probes connected to battery positive supply to any ground pins,
as this will DESTROY the ECM.
• Use care when probing connectors for wir- ing checks. The gold plating used on low
current signal connector terminals is easy
to damage by inserting a probe.
• Do not use probes that pierce wiring insula- tion since they damage/sever wiring, leav-
ing it vulnerable to corrosion.

Technical TrainingNP10-V8JLR: AJ133 5.0-Liter DFI V8 Engine04/14/20093-25
Engine Management SystemHeated Oxygen Sensors
Safety Precautions
WARNINGS:
• Anti-seize compound used on service sensor threads may be a health hazard. Avoid skin
contact.
• Exhaust system components, catalysts in particular, operate at high temperatures and
remain hot for a long time after operation.
CAUTIONS:
• Oxygen sensors must be treated with the utmost care before and during the fitting
process. The sensors have ceramic material
within them that can easily crack if
dropped or over-torqued. They must be
tightened to the specified torque figure with
a calibrated torque wrench. Care should be
taken not to contaminate the sensor tip
when the anti-seize compound is used on
the thread.
• To prevent damage to the sensors, a special tool (box spanner) should be used when
removing.
• If the sensor sticks in the exhaust, apply de- seize product and use a repeating tighten
and loosen strategy.
• Ensure that the sensor harness is robustly secured away from moving or hot parts. Failure Modes
• Mechanical fitting and integrity of the sensor (i.e.
cracked)
• Sensor open circuit/disconnected
• Short circuit to battery voltage or ground.
• Lambda ratio outside operating band
• Crossed sensors (RH bank fitted to LH bank and vice-versa)
• Contamination from leaded fuel or other sources
• Harness damage
• Air leak into exhaust system (cracked pipe/weld or loose fixings)
Failure Symptoms
• Default to open loop fuel metering
• High CO reading
• Strong smell of sulfur (rotten eggs) until default condition
• Excess emissions
• Unstable operation
• Reduced performance

Technical TrainingNP10-V8JLR: AJ133 5.0-Liter DFI V8 Engine04/14/20093-27
Engine Management SystemIgnition Coils
IGNITION COILS
The ignition coil operates according to the laws of induc-
tion. The unit consists of two magnetically-coupled cop-
per coils (primary and secondary windings).The coil has
a 3-pin connector and incorporates an internal switching
module.
Energy is stored in the primary winding’s magnetic field
by allowing a current to flow through the primary circuit
switched by the switching module.
At the firing point the current flow is interrupted by the
ECM, which induces secondary voltage in the coil’s sec-
ondary winding.
The secondary circuit has a diode on the ground side in
order to reduce any undesired switch-on voltage, which
could lead to misfiring into the intake manifold to an
uncritical value.
The switching module will limit the primary current to a
maximum value. It also limits the maximum primary
voltage by voltage clamping. This protects the switching
module and (along with other parameters) determines
the maximum possible secondary voltage. Safety Precautions
WARNING:
• Ignition coils generate high voltages that can cause personal injury. Appropriate
safety instructions on handling high volt-
ages must be observed.
CAUTIONS:
• The spark plugs fitted are critical to the performance of the ignition and misfire
detection systems. No attempt should be
made to ‘clean’ or ‘gap’ these spark plugs.
They are very reliable and unlikely to cause
problems. If a faulty spark plug is sus-
pected, try substituting it before condemn-
ing it. It is essential that only factory-
approved spark plugs be used in service.
DO NOT attempt to use ‘equivalent’ spark
plugs, even if they are of a similar design.
Use of unapproved spark plugs will cause
the misfire detection system to malfunction
and erroneously store misfire faults.
• To avoid damage to the insulator, always use the correct specified spark plugs and correct
plug removal/refit plug socket.
NOTE: A single capacitor is used in the engine harness to
suppress interference from the ignition coil power supply.
Radio Frequency Interference Suppressor
The radio frequency interference (RFI) suppressor is
mounted on the harness carrier bracket on at the upper
rear of the engine.
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