2007 ISUZU KB P190 check engine

Engine Mechanical – V6 Page 6A1–28

2 Diagnosis
2.1 Engine Diagnosis
Begin engine mechanical system diagnosis by reviewing the disassembled views provided in 1.2 Engine Components
and 1.4 Engine Construction. Reviewing the description and operation information provided will assist in determining
whether the condition described by the customer is a fault or normal engine operation.
2.2 Symptoms
Strategy Based Diagnosis
1 Review the system operations to familiarise yourself with the system functions, refer to 1 General Information and 6C1-1 Engine Management General Information.
2 Perform an engine management Diagnostic System Check, refer to 6C1-2 Engine Management – V6 – Diagnostics.
All diagnosis on a vehicle should follow a logical process. Strategy based diagnosis is a uniform approach for repairing
all vehicle systems. The strategy based diagnostic flow chart may always be used to resolve a system problem. The
diagnostic flow chart is the place to start when repairs are required. For a detailed explanation of strategy based
diagnosis and the flow chart, refer to 6C1-2 Engine Management – V6 – Diagnostics.
Visual / Physical Inspection
1 Inspect the vehicle for aftermarket accessories which may adversely affect engine operation.
2 Inspect the easily accessible or visible system components for obvious signs of damage or conditions that may cause the symptom.
3 Check the engine lubrication system for the following:
• correct oil level,
• correct lubricant viscosity,
• correct oil filter application, and
• contaminated or burnt oil.
4 Confirm the exact operating conditions under which the fault occurs. Note factors such as:
• engine speed (r.p.m.),
• ambient temperature,
• engine temperature,
• engine warm-up time, and
• vehicle road speed.
5 Compare the engine sounds, if applicable, to a known good engine, and ensure you are not trying to diagnose a normal operating condition.
Intermittent
For intermittent faults, test the vehicle under the same conditions the customer reported in order to confirm whether the
system is operating correctly.

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–29

2.3 Engine Misfire without Internal Engine
Noises
Cause Correction
Abnormalities, severe cracking, bumps or missing areas in
the accessory drive belt.
Abnormalities in the accessory drive system and/or
components may cause engine speed variations that result
in a misfire diagnostic trouble code (DTC). A misfire code
may be present without an actual misfire condition. Replace the accessory drive belt, refer to 3.5
Accessory
Drive Belt.
Refer to 6C1-2 Engine Management – V6 – Diagnostics to
check for DTCs.
W orn, damaged or misaligned accessory drive components
and excessive pulley run-out may lead to a misfire DTC.
A misfire code may be present without an actual misfire
condition. Inspect the components and repair or replace as required.
Refer to 6C1-2 Engine Management – V6 – Diagnostics to
check for DTCs.
Loose or incorrectly fitted flexplate or crankshaft balancer
assembly.
A misfire DTC may be present without an actual misfire
condition. Repair or replace the flexplate or crankshaft balancer as
required, refer to 3.13 Crankshaft Balancer Assembly
or 4.3 Flexplate Assembly.
Refer to 6C1-2 Engine Management – V6 – Diagnostics to
check for DTCs
Restricted exhaust system.
A severe restriction in the exhaust flow can cause
significant loss of engine performance and may set a DTC.
Possible causes of restrictions in the exhaust system
include collapsed/dented pipes and blocked mufflers and/or
catalytic converters. Repair or replace exhaust system components as required,
refer to 8B Exhaust System.
Refer to 6C1-2 Engine Management – V6 – Diagnostics to
check for DTCs
Incorrectly installed or damaged vacuum hoses. Repair or replace vacuum hoses as required.
Incorrect sealing between the intake manifold and cylinder
heads, upper intake manifold and lower intake manifold,
throttle body and intake manifold. Repair or replace the intake manifold, throttle body gaskets,
cylinder heads, throttle body as required.
Incorrectly installed or damaged barometric
pressure(BARO) sensor and/or seal. The seal should not
be torn or damaged. Repair or replace the BARO sensor and/or seal as
required, refer to 6C1-3 Engine Management – V6 –
Service Operations.
Incorrectly installed or damaged EVAP purge solenoid
and/or O-ring seal. Repair or replace the EVAP purge solenoid and/or seal as
required, refer to 6C1-3 Engine Management – V6 –
Service Operations
W orn or loose stationary hydraulic lash adjusters (SHLA)
and/or rocker arms.
The SHLAs, rocker arms and roller bearings should be
intact and in the correct position. Replace the SHLAs and/or rocker arms as required, refer to
3.21 Stationary Hydraulic Lash Adjuster or 3.20
Rocker Arm.
Stuck valves.
Carbon build up on the valve stems can result in the valves
not closing correctly. Repair or replace as required, refer to 3.22 Cylinder Head
Assembly.
Excessively worn or misaligned timing chain/s. Replace the timing chain/s and components as required,
refer to 3.16 Timing Chains, Tensioners, Shoes and
Guides.
W orn camshaft lobes. Replace the camshaft/s and SHLAs as required, refer to
3.19 Camshaft or 3.21 Stationary Hydraulic Lash
Adjuster.
Excessive oil pressure.
A lubrication system with excessive oil pressure may lead
to excessive lash adjuster pump-up and loss of
compression. 1 Perform an oil pressure test, refer to 3.1
Engine Oil.
2 Repair or replace the engine oil pump as required, refer to 3.17 Oil Pump Assembly.

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–30

Cause Correction
Faulty cylinder head gasket and/or cracking or other
damage to the cylinder head and cylinder block coolant
passages.
Coolant consumption may or may not cause the engine to
overheat. 1 Inspect the spark plugs for coolant saturation, refer to
6C1-3 Engine Management – V6 – Service
Operations.
2 Inspect the cylinder heads, cylinder block and/or head gaskets, refer to 3.22 Cylinder Head Assembly and/or
4.7 Cylinder Block.
3 Repair or replace components as required.
W orn piston rings.
Oil consumption may or may not cause the engine to
misfire. 1 Inspect the spark plugs for oil deposits, refer to 6C1-3
Engine Management – V6 – Service Operations.
2 Check the cylinders for a loss of compression, refer to 2.15 Engine Compression Test.
3 Perform compression testing to identify the cause of low compression.
4 Repair or replace components as required.
A damaged crankshaft reluctor wheel.
A damaged crankshaft reluctor wheel can result in different
symptoms depending on the severity and location of the
damage.
Systems with severe reluctor ring damage may exhibit
periodic loss of crankshaft position, stop delivering a signal,
and then re-sync the crankshaft position.
Systems with slight reluctor ring damage may exhibit no
loss of crankshaft position and no misfire may occur,
however, a DTC may set. Replace the crankshaft as required, refer to 4.6
Crankshaft and Main Bearings.
Refer to 6C1-2 Engine Management – V6 – Diagnostics to
check for DTCs
2.4 Engine Misfire with Abnormal Internal Lower Engine Noises
Cause Correction
Abnormalities, severe cracking, bumps or missing areas in
the accessory drive belt.
Abnormalities in the accessory drive system and/or
components may cause engine speed variations that result
in a misfire diagnostic trouble code (DTC). A misfire code
may be present without an actual misfire condition. Replace the accessory drive belt, refer to 3.5
Accessory
Drive Belt.
Refer to 6C1-2 Engine Management – V6 – Diagnostics to
check for DTCs
W orn, damaged or misaligned accessory drive components
and excessive pulley run-out may lead to a misfire DTC.
A misfire code may be present without an actual misfire
condition. Inspect the components and repair or replace as required.
Refer to 6C1-2 Engine Management – V6 – Diagnostics to
check for DTCs
Loose or Incorrectly fitted flexplate or crankshaft balancer
assembly.
A misfire code may be present without an actual misfire
condition. Repair or replace the flexplate or crankshaft balancer as
required, refer to 3.13 Crankshaft Balancer Assembly
or 4.3 Flexplate Assembly.
W orn or broken piston rings.
Oil consumption may or may not cause an actual misfire. 1 Inspect the spark plugs for oil deposits, refer to 6C1-3
Engine Management – V6 – Service Operations.
2 Check the cylinders for a loss of compression, refer to 2.15 Engine Compression Test.
3 Perform compression testing to identify the cause of low compression.
4 Repair or replace components as required.
W orn crankshaft thrust bearing.
Severely worn thrust surfaces on the crankshaft and/or
thrust bearing may permit fore and aft movement of the
crankshaft and create a DTC without an actual misfire
condition being present. Replace the crankshaft and/or bearings as required, refer to
4.6 Crankshaft and Main Bearings.
Refer to 6C1-2 Engine Management – V6 – Diagnostics to
check for DTCs

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Engine Mechanical – V6 Page 6A1–31

2.5 Engine Misfire with Abnormal Valve
Train Noise
Cause Correction
W orn or loose stationary hydraulic lash adjusters (SHLA)
and/or valve rocker arms.
The SHLAs, rocker arm and roller bearings should be intact
and in the correct position. Replace the SHLAs and/or rocker arms as required, refer to
3.21 Stationary Hydraulic Lash Adjuster or 3.20
Rocker Arm.
Stuck valves.
Carbon build up on the valve stems can result in the valves
not closing correctly. Repair or replace as required, refer to 3.22 Cylinder Head
Assembly.
Excessively worn or misaligned timing chain/s. Replace the timing chain/s and components as required,
refer to 3.16 Timing Chains, Tensioners, Shoes and
Guides.
W orn camshaft lobes. Replace the camshaft/s and SHLAs as required, refer to
3.19 Camshaft or 3.21 Stationary Hydraulic Lash
Adjuster.
Sticking camshaft lash adjusters. Replace the lash adjusters as required, refer to 3.21
Stationary Hydraulic Lash Adjuster.
2.6 Engine Misfire with Coolant
Consumption
Cause Correction
Faulty cylinder head gasket and/or cracking or other
damage to the cylinder heads and cylinder block coolant
passages.
Coolant consumption may or may not cause the engine to
overheat. 1 Inspect the spark plugs for coolant saturation, refer to
6C1-3 Engine Management – V6 – Service
Operations.
2 Inspect the cylinder heads, cylinder block and/or head gaskets, refer to 3.22 Cylinder Head Assembly and/or
4.7 Cylinder Block.
3 Repair or replace components as required.
2.7 Engine Misfire with Excessive Oil Consumption
Cause Correction
W orn valves, valve guides and/or valve stem oil seals. 1 Inspect the spark plugs for coolant saturation, refer to 6C1-3 Engine Management – V6 – Service
Operations.
2 Repair or replace components as required, refer to 3.22 Cylinder Head Assembly.
W orn or broken piston rings.
Oil consumption may or may not cause an actual misfire. 1 Inspect the spark plugs for oil deposits, refer to 6C1-3
Engine Management – V6 – Service Operations.
2 Check the cylinders for a loss of compression, refer to 2.15 Engine Compression Test.
3 Perform compression testing to identify the cause of low compression.
4 Repair or replace components as required.
2.8 Engine Noise on Start-up, but only Lasting a Few Seconds
NOTE
A cold piston knock, which disappears in
approximately 1.5 minutes from start up, should
be considered acceptable. A cold engine knock
usually disappears when the specific cylinder’s

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–35

2.11 Engine Noise Under Load
NOTE
A cold piston knock which disappears in
approximately 1.5 minutes from start up, should
be considered acceptable. A cold engine knock
usually disappears when the specific cylinder’s
secondary ignition circuit is grounded out during
diagnosis.
A light rattle/tapping noise may indicate a valve train/upper engine concern, while a low rumble/knocking may indicate a
crankshaft, piston or lower engine concern.
Cause Correction
Low oil pressure. 1 Perform an oil pressure test, refer to 2.19
Engine Oil Pressure Diagnosis.
2 Repair or replace the engine oil pump as required, refer to 3.17 Oil Pump Assembly.
Detonation or spark knock. Confirm the correct operation of the ignition system, refer to
6C1-2 Engine Management – V6 – Diagnostics.
Loose torque converter bolts. Inspect and tighten the torque converter bolts to the correct
torque specification, refer to 7C1 Automatic – 4L60E –
General Information – 4L60E – General Information.
Cracked flexplate. Replace the flywheel/flex-plate as required, refer to 4.3
Flexplate Assembly.
Excessive connecting rod bearing clearance. Inspect the connecting rod, crankshaft and bearings and
repair/replace components as required, refer to 4.5
Pistons, Pins, Rings, Connecting Rods and Big-
end Bearings and 4.6 Crankshaft and Main Bearings.
Excessive crankshaft bearing clearance Inspect the crankshaft, cylinder block journals, main
bearings and main bearing caps and repair/replace
components as required, refer to 4.6 Crankshaft
and Main Bearings and 4.7Cylinder Block.
2.12 Engine Will Not Crank – Crankshaft Will Not Rotate
Cause Correction
Seized accessory drive system component. 1 Remove the accessory drive belt, refer to 3.5
Accessory Drive Belt.
2 Rotate the crankshaft by hand at the balancer pulley or flywheel.
3 Repair or replace accessory drive system components as required.
Hydraulically locked cylinder caused by:
• coolant in cylinder,
• oil in cylinder, or
• fuel in cylinder. 1 Remove the spark plugs and check for fluid, refer to
6C1-3 Engine Management – V6 – Service
Operations.
2 Inspect for broken head gasket/s.
3 Inspect for cracked engine block or cylinder head.
4 Inspect for sticking fuel injector.
5 Repair or replace components as required.
Seized torque converter. 1 Remove the torque converter bolts, refer to 7C1
Automatic – 4L60E – General Information – 4L60E –
General Information.
2 Rotate the crankshaft by hand at the balancer pulley or flywheel.
3 Repair or replace torque converter as required.

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ISUZU KB P190 2007

Engine Mechanical – V6 Page 6A1–39

2.16 Cylinder Leakage Test
A leakage test may be performed to measure cylinder/combustion chamber leakage. High cylinder leakage may indicate
one or more of the following:
• worn or burnt valves,
• broken valve springs,
• stuck valve lifters,
• incorrect valve lash/adjustment,
• damaged piston,
• worn piston rings,
• worn or scored cylinder bore,
• damaged cylinder head gasket,
• cracked or damaged cylinder head, or
• cracked or damaged engine block.

1 Disconnect the battery ground negative cable.
2 Remove the spark plugs from all cylinders, refer to 6C1-3 Engine Management – V6 – Service Operations.
3 Rotate the crankshaft to place the piston in the cylinder being tested at top dead centre (TDC) of the compression stroke.
4 Install a commercially available cylinder head leak down tester into the spark plug hole.
NOTE
If required, hold the crankshaft balancer bolt to
prevent the engine from rotating.
5 Apply shop air pressure to the cylinder head leak down tester and adjust according to the manufacturers instructions.
6 Record the cylinder leakage value. Cylinder leakage that exceeds 25 percent is considered excessive and may require component service. In excessive leakage situations, inspect for the following conditions:
• air leakage sounds at the throttle body or air inlet duct that may indicate a worn or burnt intake valve or a
broken valve spring,
• air leakage sounds at the exhaust system tailpipe that may indicate a worn or burnt exhaust valve or a broken
valve spring,
• air leakage sounds from the crankcase, oil level indicator tube, or oil fill tube that may indicate worn piston
rings, a damaged piston, a worn or scored cylinder bore, a damaged engine block or a damaged cylinder
head, or
• air bubbles in the cooling system may indicate a damaged cylinder head or a damaged cylinder head gasket.
7 Perform the leakage test on the remaining cylinders and record the values.
2.17 Engine Oil Consumption Diagnosis
Definition
Excessive oil consumption (not due to leaks) is the use of 3 litres or more of engine oil within 10,000 kilometres. Prior to
performing oil pressure testing, a preliminary inspection of the vehicle should be performed. During the preliminary visual
inspection, the following likely causes of excessive oil usage should be investigated.
Cause Correction
External oil leaks. Refer to 2.18 Engine Oil Leak Diagnosis.
Incorrect oil level or reading of the oil level indicator. Check for the correct oil level, refer to 3.1 Engine Oil.
Incorrect oil viscosity. Replace the engine oil, using the recommended SAE grade
of engine oil, refer to 3.1 Engine Oil.
Continuous high-speed driving or severe usage. Service vehicle more frequently, refer to 0B Lubrication and
Service.
Crankcase ventilation system restricted or malfunctioning. Repair or replace crankcase ventilation system components as required, refer to 6C1-3 Engine Management – V6 –
Service Operations.

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Engine Mechanical – V6 Page 6A1–40

Cause Correction
W orn valve guides and or valve stems. Inspect and repair valves and valve guides as required,
refer to 3.22 Cylinder Head Assembly.
W orn or damaged valve stem oil seal. Replace valve stem oil seals as required, refer to 3.22
Cylinder Head Assembly.
Piston rings broken, worn or not seated correctly. Allowing adequate time for the piston rings to seat correctly,
replace piston rings as required, refer to 4.5 Pistons, Pins,
Rings, Connecting Rods and Big-end Bearings.
Piston rings incorrectly installed or not matched to cylinder
bore oversize. Replace piston rings as required, refer to 4.5 Pistons, Pins,
Rings, Connecting Rods and Big-end Bearings.
2.18 Engine Oil Leak Diagnosis
Introduction
It is important to correctly identify the source of an engine oil leak. For example, a power steering fluid leak or spillage
during servicing can travel across the valley area of the engine and run-out the weep hole, which is located at the back of
the cylinder block. Failure to correctly identify the source of an engine oil leak can lead to unnecessary replacement of
engine components.
Most fluid leaks can be repaired by repairing or replacing the faulty component or resealing the gasket surface. However,
once a leak is identified it is important to determine and repair the cause as well as the leak itself.
Locating and Identifying the Leak
Inspect the leaking fluid and determine whether it is engine oil, transmission fluid, power steering fluid, brake fluid or
some other fluid. If unsure of the source of the leaking lubricant, a quick check of fluid levels should indicate where the
fluid is coming from, as one or more fluid level should be low.
Visual Inspection
Once the type of leaking fluid has been determined, a visual inspection of the affected system should be performed.
W hen performing the visual inspection:
1 Bring the vehicle to the normal operating temperature.
2 Park the vehicle over a large sheet of paper or other clean surface.
3 Leave the vehicle idling for 2-3 minutes, then check for dripping fluid.
4 If required, identify the type of fluid leaking and the approximate location of the leak.
5 Visually inspect the suspected area. A small mirror may assist viewing areas that are difficult to see normally.
6 Check for leaks at all sealing surfaces and fittings.
7 Check for any cracked or damaged components.
8 If the leak cannot be located, completely clean the entire engine and surrounding components, drive the vehicle at normal operating temperature for several kilometres and then repeat Steps 3 to 8.
9 If the leak still cannot be located, proceed with either the Powder Method or Black Light and Dye Method as outlined below.
Powder Method
1 Completely clean the entire engine and surrounding components.
2 Apply an aerosol type powder (e.g. foot powder) to the suspected area.
3 Operate the vehicle at normal operating temperature and at varying speeds for several kilometres.
4 Identify the source of the leak from the discoloration of the powder around the suspect components.
5 If required, use a small mirror to assist in viewing areas that are difficult to see normally.
6 Refer to Possible Causes for Engine Oil Leaks in this Section, and repair or replace components as required.
Black Light and Dye Method
A black light and die kit Tool No. J28428-E or a commercially available equivalent is available to technicians to aid in
engine oil leak diagnosis. W hen using a black light and die kit for the first time, it is recommended the technician read the
manufacturers instructions prior to using the kit.
1 Add the specified amount of dye, as per manufacturers instructions, into the engine or suspected source of the oil leak.
2 Operate the vehicle at normal operating temperature and at varying speeds for several kilometres.

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Engine Mechanical – V6 Page 6A1–42

2.19 Engine Oil Pressure Diagnosis
If the engine oil pressure is below the specified value, inspect the engine and components for the following:
• loose oil filter adaptor bolts,
• faulty oil filter adaptor seals,
• worn or faulty oil pump,
• loose oil pump bolts,
• loose, blocked or damaged oil pump suction pipe,
• faulty oil pump suction pipe seal,
• faulty oil pump pressure relief valve,
• faulty or incorrectly installed oil gallery plugs,
• excessive bearing clearance in one of the following:
• connecting rods big end/s,
• crankshaft main journal/s,
• camshaft/s,
• camshaft sprocket/s, and
• cracked, porous or restricted oil galleries, or broken lash adjuster/s.
2.20 Accessory Drive Belt Diagnosis
Tension Check
NOTE
An accessory drive belt that squeaks when the
engine is started or stopped is considered normal
and has no effect on drive belt durability.
1 Start the engine and switch off the air-conditioning system. Allow engine to run until normal operating temperature has been reached.
2 Turn the engine off and inspect the markings on the drive belt tensioner to confirm the drive belt tension is
within the operating limits.

3 If the markings on the drive belt tensioner were outside the acceptable operating limits, replace the
accessory drive belt, refer to 3.5 Accessory
Drive Belt.

NOTE
The operating limits for acceptable drive belt
tension are when the drive belt tensioner pointer
(1) is aligned between the outer edge of the
minimum and maximum tension marks (2).
Figure 6A1 – 21
Inspect
Figure 6A1 – 22 illustrates the various stages of belt wear to aid in belt replacement decisions. Condition of the belt ribs
is best judged where the belt is bent over one of the larger accessory drive system pulleys.

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