oil OPEL FRONTERA 1998 Workshop Manual

5A–39 BRAKE CONTROL SYSTEM
Diagnostic Trouble Codes
Choose and trace an appropriate flowchart by the
numbers listed below to find fault and repair.
Code
ItemDiagnosisChart No.
12Start CodeNormal—
14EHCU FunctionAbnormality in input/output, operational and
control circuitsB-2
15Power Voltage DropB-3
16CLASS–2 Communication Line Ab-
normalityB-4
21G-sensorWiring disconnectionB-5
23Transmission InputInput abnormalityB-6
24Transfer MonitorB-7
32Motor & Motor RelayShorted or disconnected coilB-8
35Valve RelayShorted or disconnected coil/wiringB-9
41FL Holding Solenoid ValveShorted or disconnected coil/wiringB-10
42FL Decompression Solenoid ValveShorted or disconnected coil/wiringB-11
43FR Holding Solenoid ValveShorted or disconnected coil/wiringB-12
44FR Decompression Solenoid ValveShorted or disconnected coil/wiringB-13
45Rear Holding Solenoid ValveShorted or disconnected coil/wiringB-14
46Rear Decompression Solenoid ValveShorted or disconnected coil/wiringB-15
51FL Wheel Speed SensorDisconnected coil/wiringB-16
52FR Wheel Speed SensorDisconnected coil/wiringB-17
53RL Wheel Speed SensorDisconnected coil/wiringB-18
54RR Wheel Speed SensorDisconnected coil/wiringB-19
61FL Wheel Speed SensorShorted coil/wiringB-20
62FR Wheel Speed SensorShorted coil/wiringB-21
63RL Wheel Speed SensorShorted coil/wiringB-22
64RR Wheel Speed SensorShorted coil/wiringB-23
65Sensor Signal InputWrong number of teethB-24

6A–1
ENGINE MECHANICAL
ENGINE
CONTENTS
Engine Mechanical 6A. . . . . . . . . . . . . . . . . . . . . .
Engine Cooling 6B. . . . . . . . . . . . . . . . . . . . . . . . .
Engine Fuel 6C. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Electrical 6D1. . . . . . . . . . . . . . . . . . . . . . . .
Ignition System 6D2. . . . . . . . . . . . . . . . . . . . . . . . .
Starting and Charging System 6D3. . . . . . . . . . . . Driveability and Emissions 6E. . . . . . . . . . . . . . . .
Engine Exhaust 6F. . . . . . . . . . . . . . . . . . . . . . . . .
Engine Lubrication 6G. . . . . . . . . . . . . . . . . . . . . .
Engine Speed Control System 6H. . . . . . . . . . . .
Inducton 6J. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ENGINE MECHANICAL
CONTENTS
Service Precaution 6A–2. . . . . . . . . . . . . . . . . . . . . .
General Description 6A–3. . . . . . . . . . . . . . . . . . . . .
Engine Diagnosis 6A–4. . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head Cover LH 6A–18. . . . . . . . . . . . . . . . .
Removal 6A–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A–19. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head Cover RH 6A–21. . . . . . . . . . . . . . . . .
Removal 6A–21. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A–22. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Common Chamber 6A–24. . . . . . . . . . . . . . . . . . . . . .
Removal 6A–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A–24. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust Manifold LH 6A–26. . . . . . . . . . . . . . . . . . . . .
Removal 6A–26. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A–26. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust Manifold RH 6A–27. . . . . . . . . . . . . . . . . . . .
Removal 6A–27. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A–27. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft Pulley 6A–28. . . . . . . . . . . . . . . . . . . . . . .
Removal 6A–28. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A–28. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Timing Belt 6A–29. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 6A–29. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A–30. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Camshaft 6A–33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 6A–33. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A–33. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head 6A–37. . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 6A–37. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A–37. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Valve Stem Oil Controller , Valve Spring and
Valve Guide 6A–39. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 6A–39. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A–39. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Piston, Piston Ring and Connecting Rod 6A–40. . . Removal 6A–40. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A–41. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft and Main Bearings 6A–42. . . . . . . . . . . .
Removal 6A–42. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A–43. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Oil Seal 6A–47. . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 6A–47. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A–47. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Assembly 6A–48. . . . . . . . . . . . . . . . . . . . . . . .
Removal 6A–48. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A–48. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head 6A–52. . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head and Associated Parts 6A–52. . . . .
Disassembly 6A–52. . . . . . . . . . . . . . . . . . . . . . . . . .
Clean 6A–53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 6A–53
. . . . . . . . . . . . . . . . . .
Reassembly 6A–53. . . . . . . . . . . . . . . . . . . . . . . . . .
Valve Spring, Oil Controller, Valve,
Valve Guide 6A–56. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Valve Spring, Oil Controller, Valve,
Valve Guide and Associated Parts 6A–56. . . . . . .
Disassembly 6A–56. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 6A–57. . . . . . . . . . . . . . . . . .
Reassembly 6A–60. . . . . . . . . . . . . . . . . . . . . . . . . .
Valve Clearance Adjustments 6A–61. . . . . . . . . . . . .
Camshaft 6A–63. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Camshaft and Associated Parts 6A–63. . . . . . . . .
Disassembly 6A–63. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 6A–64. . . . . . . . . . . . . . . . . .
Reassembly 6A–66. . . . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft 6A–69. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft and Associated Parts 6A–69. . . . . . . .
Disassembly 6A–69. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 6A–70. . . . . . . . . . . . . . . . . .
Inspection and Repair 6A–71. . . . . . . . . . . . . . . . . .
Reassembly 6A–73. . . . . . . . . . . . . . . . . . . . . . . . . .

6A–3
ENGINE MECHANICAL
General Description
Engine Cleanliness And Care
An automobile engine is a combination of many
machined, honed, polished and lapped surfaces with
tolerances that are measured in the thousandths of a
millimeter (ten thousandths of an inch). Accordingly,
when any internal engine parts are serviced, care and
cleanliness are important. Throughout this section, it
should be understood that proper cleaning and protection
of machined surfaces and friction areas is part of the
repair procedure. This is considered standard shop
practice even if not specifically stated.
A liberal coating of engine oil should be applied to all
friction areas during assembly to protect and lubricate
the surfaces on initial operation.
Whenever valve train components, pistons, piston
rings, connecting rods, rod bearings, and crankshaft
journal bearings are removed for service, they should
be retained in order.
At the time of installation, they should be installed in
the same locations and with the same mating
surfaces as when removed.
Battery cables should be disconnected before any
major work is performed on the engine. Failure to
disconnect cables may result in damage to wire
harness or other electrical parts.
The six cylinders of this engine are identified by
numbers; Right side cylinders 1, 3 and 5, Left side
cylinders 2, 4 and 6, as counted from crankshaft
pulley side to flywheel side.
General Information on Engine Service
The following information on engine service should be
noted carefully, as it is important in preventing damage
and contributing to reliable engine performance:
When raising or supporting the engine for any reason,
do not use a jack under the oil pan. Due to the small
clearance between the oil pan and the oil pump
strainer, jacking against the oil pan may cause
damage to the oil pick–up unit.
The 12–volt electrical system is capable of damaging
circuits. When performing any work where electrical
terminals could possibly be grounded, the ground
cable of the battery should be disconnected at the
battery.
Any time the intake air duct or air cleaner is removed,
the intake opening should be covered. This will
protect against accidental entrance of foreign
material into the cylinder which could cause extensive
damage when the engine is started.
Cylinder Block
The cylinder block is made of aluminum die–cast casting
for 75
V–type six cylinders. It has a rear plate integrated
structure and employs a deep skint. The cylinder liner is
cast and the liner inner diameter and crankshaft journal
diameter are classified into grades. The crankshaft is
supported by four bearings of which width of No.3 bearing
on the body side is different in order to support the thrust
bearing. The bearing cap is made of nodular cast iron and
each bearing cap uses four bolts and two side bolts.
Cylinder Head
The cylinder head, made of aluminum alloy casting
employs a pent–roof type combustion chamber with a
spark plug in the center. The intake and exhaust valves
are placed in V–type design. The ports are cross–flow
type.
Va l v e Tr a i n
Intake and exhaust camshaft on the both side of banks
are driven through an camshaft drive gear by timing belt.
The valves are operated by the camshaft and the valve
clearance is adjusted to select suitable thickness shim.
Intake Manifold
The intake manifold system is composed of the aluminum
cast common chamber and intake manifold attached with
six fuel injectors.
Exhaust Manifold
The exhaust manifold is made of nodular cast iron.
Pistons and Connecting Rods
Aluminum pistons are used after selecting the grade that
meets the cylinder bore diameter. Each piston has two
compression rings and one oil ring. The piston pin is made
of chromium steel is offset 1mm toward the thrust side,
and the thrust pressure of piston to the cylinder wall varies
gradually as the piston travels. The connecting rods are
made of forged steel. The connecting rod bearings are
graded for correct seze selection.
Crankshaft and Bearings
The crankshaft is made of Ductile cast–iron. Pins and
journals are graded for correct size selection for their
bearing.
Engine Lubrication
The oil discharged by a trochoid–type oil pump driven by
the crankshaft is fed through full–flow oil filter and to the oil
gallery provided under the crankshaft bearing cap. The oil
is then led to the crankshaft journals and cylinder head.
The crank pins are lubricated with oil from crankshaft
journals through oil holes. Also, an oil jet is fed to each
cylinder from crankshaft juornals on the connecting rod
for piston cleaning. The oil pan flange is dealed with liquid
packing only; do not deform or damage the flange surface
during removal or installation.

6A–4
ENGINE MECHANICAL
Engine Diagnosis
Hard Starting
1. Starting Motor Does Not Turn Over
Troubleshooting Procedure
Turn on headlights and starter switch.
Condition
Possible causeCorrection
Headlights go out or dim
considerably
Battery run down or under chargedRecharge or replace battery
considerablyTerminals poorly connectedClean battery posts and terminals
and connect properly
Starting motor coil circuit shortedOverhaul or replace
Starting motor defectiveOverhaul or replace
2. Ignition Trouble — Starting Motor Turns Over But Engine Does Not Start
Spark Test
Disconnect an igniton coil from any spark plug. Connect
the spark plug tester 5–8840–0607–0, start the engine,
a n d c h e c k i f a s p a r k i s g e n e r a t e d in t h e s p a r k p l u g t e s t e r.
Before starting the engine, make sure that the spark plugtester is properly grounded. To avoid electrical shock, do
not touch the part where insulation of the igniton coil is
broken while the engine is running.
Condition
Possible causeCorrection
Spark jumps across gapSpark plug defectiveClean, adjust spark gap or replace
Ignition timing incorrectRefer to Ignition System
Fuel not reaching fuel injector(s) or
engineRefer to item 3 (Trouble in fuel
system)
Valve timing incorrectAdjust
Engine lacks compressionRefer to item 4 (Engine lacks
compression)
No sparking takes placeIgnition coil disconnected or brokenConnect properly or replace
Electronic Ignition System with
moduleReplace
Poor connections in engine harnessCorrect
Powertrain Control Module cable
disconnected or defectiveCorrect or replace
3. Trouble In Fuel System
Condition
Possible causeCorrection
Starting motor turns over and spark
occurs but engine does not start
Fuel tank emptyFill
occurs but engine does not start.Water in fuel systemClean
Fuel filter cloggedReplace filter
Fuel pipe cloggedClean or replace
Fuel pump defectiveReplace
Fuel pump circuit openCorrect or replace
Evaporative Emission Control
System circuit cloggedCorrect or replace
Multiport Fuel Injection System faultyRefer to “Electronic Fuel Injection”
section

6A–5
ENGINE MECHANICAL
4. Engine Lacks Compression
Condition
Possible causeCorrection
Engine lacks compressionSpark plug loosely fitted or spark
plug gasket defectiveTighten to specified torque or replace
gasket
Valve timing incorrectAdjust
Cylinder head gasket defectiveReplace gasket
Valve incorrectly seatedLap valve
Valve stem seizedReplace valve and valve guide
Valve spring weakened or brokenReplace
Cylinder or piston rings wornOverhaul engine
Piston ring seizedOverhaul engine.
Engine Compression Test Procedure
1. Start and run the engine until the engine reaches
normal operating temperature.
2. Turn the engine off.
3. Remove all the spark plugs.
4. Remove ignition coil fuse (15A) and disable the
ignition system.
5. Remove the fuel pump relay from the relay and fuse
box.
6. Engage the starter and check that the cranking speed
is approximately 300 rpm.7. Install cylinder compression gauge into spark plug
hole.
8. With the throttle valve opened fully, keep the starter
engaged until the compression gage needle reaches
the maximum level. Note the reading.
9. Repeat the test with each cylinder.
If the compression pressure obtained falls below the
limit, engine overhaul is necessary.
Limit; 1000 kPa (145 psi)

6A–7
ENGINE MECHANICAL
Condition CorrectionPossible cause
OthersEngine lacks compressionRefer to “Hard Start”
Valve incorrectly seatedLap valve
Air Cleaner Filter cloggedReplace filter element
Valve timing incorrectReadjust
Idle air control valve brokenReplace
Fast idle solenoid defectiveReplace
Positive Crankcase Ventilation valve
defective or cloggedReplace
Rough Engine Running
ConditionPossible causeCorrection
Engine misfires periodicallyIgnition coil layer shortedReplace
Spark plugs foulingClean or install hotter type plug
Spark plug(s) insulator nose leakingReplace
Fuel injector(s) defectiveReplace
Powertrain control module faultyReplace
Engine knocks periodicallySpark plugs running too hotInstall colder type spark plugs
Powertrain control module faultyReplace
Engine lacks powerSpark plugs fouledClean
Fuel injectors defectiveReplace
Mass Airflow Sensor or Intake
Airflow Sensor circuit defectiveCorrect or replace
Manifold Absolute Pressure (MAP)
Sensor or Manifold Absolute
Pressure Sensor circuit defectiveCorrect or replace
Engine Coolant Temperature Sensor
or Engine Coolant Temperature
Sensor circuit defectiveCorrect or replace
Powertrain Control Module faultyReplace
Intake Air Temperature Sensor or
Intake Air Temperature Sensor
circuit defectiveCorrect or replace
Throttle Position Sensor or Throttle
Position Sensor circuit defectiveCorrect or replace
Knock Sensor or Knock Sensor
circuits defectiveCorrect or replace
Knock Sensor Module or Knock
Sensor Module circuits defectiveCorrect or replace

6A–10
ENGINE MECHANICAL
Engine Lacks Power
ConditionPossible causeCorrection
Trouble in fuel systemFuel Pressure Control Valve not
working normallyReplace
Fuel injector cloggedClean or replace
Fuel pipe cloggedClean
Fuel filter clogged or fouledReplace
Fuel pump drive circuit not working
normallyCorrect or replace
Fuel tank not sufficiently breathing
due to clogged Evaporative
Emission Control System circuitClean or replace
Water in fuel systemClean
Inferior quality fuel in fuel systemUse fuel of specified octane rating
Powertrain Control Module supplied
poor voltageCorrect circuit
Throttle Position Sensor cable
broken or poor connectionsCorrect or replace
Throttle Position Sensor defectiveReplace
Mass Airflow Sensor not working
normallyReplace
Manifold Absolute Pressure Sensor
not working normallyReplace
Intake Air Temperature Sensor not
working normallyReplace
Engine Coolant Temperature Sensor
circuit open or shortedCorrect or replace
Engine Coolant Temperature Sensor
defectiveReplace
Powertrain Control Module defectiveReplace
Trouble in intake or exhaust systemAir Cleaner Filter cloggedReplace filter element
Air duct kinked or flattenedCorrect or replace
Ignition failure————Refer to Hard Start Troubleshooting
Guide
Heat range of spark plug inadequateInstall spark plugs of adequate heat
range
Ignition coil defectiveReplace

6A–11
ENGINE MECHANICAL
Condition CorrectionPossible cause
Engine overheatingLevel of Engine Coolant too lowReplenish
Fan clutch defectiveReplace
Incorrect fan installedReplace
Thermostat defectiveReplace
Engine Coolant pump defectiveCorrect or replace
Radiator cloggedClean or replace
Radiator filler cap defectiveReplace
Level of oil in engine crankcase too
low or wrong engine oilChange or replenish
Resistance in exhaust system
increasedClean exhaust system or replace
defective parts
Throttle Position Sensor adjustment
incorrectReplace with Throttle Valve ASM
Throttle Position Sensor circuit open
or shortedCorrect or replace
Cylinder head gasket damagedReplace
Engine overcoolingThermostat defectiveReplace (Use a thermostat set to
open at 82
C (180F))
Engine lacks compression————Refer to Hard Start
OthersTire inflation pressure abnormalAdjust to recommended pressures
Brake dragAdjust
Clutch slippingAdjust or replace
Level of oil in engine crankcase too
highCorrect level of engine oil
Exhaust Gas Recirculation Valve
defectiveReplace
Engine Noisy
Abnormal engine noise often consists of various noises
originating in rotating parts, sliding parts and othermoving parts of the engine. It is, therefore, advisable to
locate the source of noise systematically.
Condition
Possible causeCorrection
Noise from crank journals or from
crank bearings
(Faulty crank journals and crankOil clearance increased due to worn
crank journals or crank bearingsReplace crank bearings and
crankshaft or regrind crankshaft and
install the undersize bearing
yj
bearings usually make dull noise that
becomes more evident when
accelerating)Crankshaft out of roundReplace crank bearings and
crankshaft or regrind crankshaft and
install the undersize bearing
Crank bearing seizedCrank bearing seized. Replace crank
bearings and crankshaft or regrind
crankshaft and install the undersize
bearing
Troubleshooting Procedure
Short out each spark plug in sequence using insulated
spark plug wire removers. Locate cylinder with defectivebearing by listening for abnormal noise that stops when
spark plug is shorted out.

6A–14
ENGINE MECHANICAL
Condition CorrectionPossible cause
Trouble in emission control systemHeated Oxygen Sensor circuit openCorrect or replace
Heated Oxygen Sensor defectiveReplace
Signal vacuum hose loosely fitted or
defectiveCorrect or replace
EGR Valve circuit open or shortedCorrect or replace
Exhaust Gas Recirculation Valve
defectiveReplace
ECT Sensor circuit open or shortedCorrect or replace
Canister Purge Valve circuit open or
shortedCorrect or replace
Canister Purge Valve defectiveReplace
ECT Sensor defectiveReplace
Positive Crankcase Ventilation
(PCV) valve and hose cloggedCorrect or replace
Evaporator systemRefer to Section 6E
Trouble in ignition system————Refer to “Engine Lacks Power”
Trouble in cylinder head partsCarbon deposits in combustion
chamberRemove carbon
Carbon deposit on valve, valve seat
and valve guideRemove carbon
Engine Oil Consumption Excessive
ConditionPossible causeCorrection
Oil leakingOil pan drain plug looseRetighten or replace gasket
Crankcase fixing bolts loosenedRetighten
Oil pan setting bolts loosenedRetighten
Oil pan gasket brokenReplace gasket
Front cover retaining bolts loose or
gasket brokenRetighten or replace gasket
Head cover fixing bolts loose or
gasket brokenRetighten or replace gasket
Oil cooler adapter crackedReplace
Oil cooler center bolt looseRetighten
Oil cooler O–ring brokenReplace
Oil cooler piping loose or brokenRetighten or replace
Oil filter adapter crackedReplace
Oil filter attaching bolt loose or rubber
gasket brokenRetighten or replace oil filter
Oil cooler brokenReplace
Crankshaft front or rear oil seal
defectiveReplace oil seal
Oil pressure unit loose or brokenRetighten or replace
Blow–by gas hose brokenReplace hose
Positive Crankcase Ventilation Valve
cloggedClean
Engine/Transmission coupling failedReplace oil seal

6A–15
ENGINE MECHANICAL
Condition CorrectionPossible cause
Oil leaking into combustion
chambers due topoor seal in valve
Valve stem oil seal defectiveReplace
chambers due to oor seal in valve
systemValve stem or valve guide wornReplace valve and valve guide
Oil leaking into combustion
chambers due to poor seal in cylinder
t
Cylinders and pistons worn
excessivelyReplace cylinder body assembly and
pistons
partsPiston ring gaps incorrectly
positionedCorrect
Piston rings set with wrong side upCorrect
Piston ring stickingReplace cylinder body assembly and
pistons
Piston ring and ring groove wornReplace pistons and others
Return ports in oil rings cloggedClean piston and replace rings
Positive Crankcase Ventilation
System malfunctioningPositive Crankcase Ventilation Valve
cloggedClean
OthersImproper oil viscosityUse oil of recommended S.A.E.
viscosity
Continuous high speed driving
and/or severe usage such as trailer
towingContinuous high speed operation
and/or severe usage will normally
cause increased oil consumption
Fuel Consumption Excessive
ConditionPossible causeCorrection
Trouble in fuel systemMixture too rich or too lean due to
trouble in fuel injection systemRefer to “Abnormal Combustion”
Fuel cut function does not workRefer to “Abnormal Combustion”
Trouble in ignition systemMisfiring or abnormal combustion
due to trouble in ignition systemRefer to “Hard Start” or “Abnormal
Combustion”
OthersEngine idle speed too highReset Idle Air Control Valve
Returning of accelerator control
sluggishCorrect
Fuel system leakageCorrect or replace
Clutch slippingCorrect
Brake dragCorrect
Selection of transmission gear
incorrectCaution operator of incorrect gear
selection
Excessive Exhaust Gas
Recirculation flow due to trouble in
Exhaust Gas Recirculation systemRefer to “Abnormal Combustion”