SECTION 6F1 - ENGINE TUNE – V6 ENGINE
IMPORTANT
Before perfo rming any Service Operation or other procedu re described in this Section , refer to Section 00
CAUTIONS AND NOTES for correct workshop practices with regard to safety and/or property damage.
CONTENTS
1. GENERAL INFORMATION
1.1 VEHICLE EMISSION CONTROL INFORMATION
2. ENGINE TUNE RECOMMENDATIONS
3. ENGINE TUNING DATA
3.1 TUNING SERVICE NOTES
3.2 CYLINDER BALANCE CHECK
IGNITION
FUEL
MECHANICAL
4. SPECIAL TOOLS
1. GENERAL INFORMATION
Engine tuning, although simplified by electronic control of the air/fuel mixture and ignition timing, is of great
importance due to the susceptibility of the catalytic converter to damage caused by rich air/fuel mixture. The
Powertrain Control Module (PCM) controls the air/fuel ratio to near optimum condition. A rich mixture can be
induced by faulty spark plugs or leads or a fault in the engine management system, refer to
Section 6C1, POWERTRAIN MANAGEMENT – V6 ENGINE.
The PCM will set a Diagnostic Trouble Code (DTC) and the words “Check Engine” together with an icon will be
displayed in the instrument cluster multi-function display, in the event of the mixture continuing to operate outside
the specified limits. Prolonged operation with a rich mixture may damage the catalytic converter, refer to
Section 6E1, 1.6 THREE-WAY CATALYTIC CONVERTER.
1.1 VEHICLE EMISSION CONTROL INFORMATION
Engine tune specifications necessary to achieve
the correct emission levels are located on the
Vehicle Emission Control Information Label,
located in the engine compartment. Refer to the
label before adjusting the engine.
To maintain the performance and emission control
levels specified for the vehicle, it is necessary for
regular maintenance to be performed in
accordance with the schedule set out in the VY
Series Owner's Handbook.
Figure 6F1-1
Figure 6F1-2
The following engine tune recommendation chart lists the items that require attention when tuning the engine.
Cross-references to the appropriate section in the VY service manual are also provided.
There is no provis ion for ignition tim ing, idle s peed and idle m ixture adj ustm ents on the VY Series Models with a V6
engine, refer to Section 6C1, POWERTRAIN MANAGEMENT – V6 ENGINE.
The Engine Tune Data Chart provides condensed engine tuning data.
NOTE: The use of unleaded petrol will result in black tail pipe deposits rather than the familiar grey colour.
Therefore, the black colour does not indicate a poor state of engine tune.
2. ENGINE TUNE RECOMM E NDATIONS
ENGINE TUNE RECOMMENDATI ONS VY SERVICE MANUAL
REFERENCE SECTI ON
ENGINE COMPRESSION TEST SECTION 6A 1, 2.6 COMPRESSI ON
CHECK, ALSO REFER TO 3.1 TUNI NG
SERVICE NOTES.
ENGINE DRIVE BELT CHECK SECTION 6A1, 2.7 DRIVE BELT.
COOLING SYST E M CHECK FOR LEAKS SECTION 6B 1, 3.3 CHECKI NG A ND
FILLING COOLING SYSTEM.
VALVE LASH ADJUSTMENT NON-ADJUSTABLE HYDRAULIC
LIFTERS
IDLE SPEED NON-ADJUSTABLE
IDLE MIXTURE NON-ADJUSTABLE
AIR CLEANER CHECK OR REPLACE, TEST FOR LEAKS SECTION 6C1-3, 3.5 AIR CLEA NE R
ASSEMBLY.
FUEL FILTER CHECK AND REP LACE SECTION 6C1-3 9 FUEL FILTER.
SPARK PLUGS CLEAN, ADJUST OR REPLACE SECTION 6C1-3, 4.7 SPARK PLUGS.
SPARK PLUG LEADS T EST FOR CONT INUITY SECTION 6C1-3, 4.6 SPARK PLUG
LEADS.
IGNITION TIMING NON-ADJUSTABLE
EXHAUST SYSTEM CHECK FO R EXCESSIVE BACK
PRESS URE, GENERAL CONDITION A ND
OXYGEN SENSOR OPERATION
SECTION 8B, EXHAUST SYSTEM,
SECTION 6C1-3, 2.6 OXYGEN SENSOR
ENGINE VENTILA T ION CHECK SECTION 6E1, 1.3 ENGINE
VENTILATION.
EVAPORATIVE EMISSION CONTROL CHECK LI NE S, HOSES AND CANISTER SECTION 6E1, 1.4 EVAPORATIVE
EMISSION CONTROL.
BATT ERY AND CAB L E S CHECK SECTION 12A , BATT E RY AND CABLES.
3. ENGINE TUNI NG DATA
SPARK PLUGS
ENGINE TRANSMISSION IDLE SPEED (RPM) IGNITI ON TIMING TYPE GAP (mm)
MANUAL 775 ± 50
725 ± 50
(IN NEUTRAL)
3.8 LITRE P.F.I. V6
NORMALLY
ASPIRATED
AUTOMATIC 650 ± 50
(IN DRIV E)
PCM
CONTROLLED
(NON-
ADJUSTABLE)
NGK
BPR6EFS-15
OR
DENSO
T20EPRU-15
1.5 + 0.0
- 0.1
775 ± 50
(IN NEUTRAL)
3.8 LITRE P.F.I. V6
NORMALLY
ASPIRATED
(BRAZIL)
AUTOMATIC 700 ± 50
(IN DRIV E)
PCM
CONTROLLED
(NON-
ADJUSTABLE)
NGK
BPR6EFS-15
OR
DENSO
T20EPRU-15
1.5 + 0.0
- 0.1
NOTE: Idle speed is controlled by the P CM and varies with: – Battery vol tage
– Engine temperature
– Air conditioning usage
3.1 TUNING SERVI CE NOTES
CAUTION: To prevent fuel being injected into
the cylinders and the ignition during cranking,
remove the EFI relay (1) when performing a
compression test. This will avoid damaging the
catalytic converter with unburned fuel.
For compression testing procedure and
specifications, refer to Section 6A1, 2.6
COMPRESSION CHECK.
1. Do not oper ate the engine with any spark plugs
or spark plug leads disconnected as:
a. The ignition system or PCM may be damaged.
b. The resultant mixture could damage the
catalytic converter.
2. Make all engine checks with engine coolant
and oil at normal operating temperatures,
preferably those temperatures reached while
driving.
3. Ensure the air conditioning, where fitted, is
switched OFF.
4. Verify that the words “Check Engine” and
accompanying icon are not displayed in the
instrument cluster multi-function display when
the engine is running.
Figure 6F1-3
3.2 CYLINDER BALANCE CHECK
1. Connect the Tech 2 (4) to the Data Link
Connector (DLC) (1) via the DLC Adaptor (2)
and DLC Cable (3).
2. Select VY Commodore / Engine / Functional
Tests / Power Balance.
3. Perform Power Balance as directed by the
Diagnostic Scan Tool.
NOTE 1: RPM readings displayed on the
Diagnostic Scan Tool should be within 50 RPM of
the idle engine speed for all cylinders
NOTE 2: Any cylinder that does not caus e a drop in
engine idle speed is misfiring.
NOTE 3: For further information on the usage of
Tech 2, refer to Section 0C, TECH 2.
Once the problematic cylinder has been identified,
the cause of the problem will still need to be
determined. Reasons for the fault include fuel,
spark or engine mechanical problems.
The following checks are to assist in isolating
the cause of the engine misfire. For
additional diagnostic information, refer to
Section 6C1, POWERTRAIN MANAGEMENT –
V6 ENGINE.
Figure 6F1-4
IGNITION
1. Remove the spark plug lead from the plug and
the engine harness connector from the injector
of the misfiring cylinder.
2. Install the Test Plug, Tool No. 7230 (1) and
connect it to an engine earth point.
NOTE 1: Failure to properly earth the Test Plug
may result in damage to the ignition system
components due to excessive secondary voltages
required to fire it.
NOTE 2: Avoid placing the test plug near sensors,
modules or other electronic equipment that m ay be
affected by electromagnetic interference.
3. Disconnect the spark plug wire and the engine
wiring harness from the injector of the
corres ponding cylinder. Connect the spark plug
lead directly to the engine earth.
4. Start and run the engine. If the tester shows a
good spark, check for faulty spark plug.
5. If there is a weak spark or no spark at all,
check the spark plug lead for a short circuit to
the earth, or open or very high resistance
NOTE: If any lead is open circuited, recheck coil
secondary resistance, it may have been damaged
by high voltage produced by open circuit.
Figure 6F1-5
FUEL
1. Disconnect the engine harness connector from
the injector of cylinder that is misfiring.
2. Install injector node light tester (1), Tool No.
J34730-2C into connector (2) and start engine.
3. Check the tester for a light flashing.
a. If the injector node light does not flash or
flashes erratically, check engine harness
between connector and PCM.
b. If the injec tor node light test er flashes regularly,
check for blocked or faulty injector, refer to
Section 6C1, POWERTRAIN MANAGEMENT
– V6 ENGINE.
Figure 6F1-6
MECHANICAL
Perform a compression test, refer to Section 6A1,
2.6 COMPRESSION CHECK.
4. SPECIAL TOOLS
TOOL NUMBER ILLUSTRATION DESCRIPTION TOOL
CLASSIFICATION
7000086I
TECH 2
DIAGNOSTIC SCAN TOOL
Used for diagnosis of vehicle
electrical system.
Previously released.
Mandatory
7230
(ST-125)
HEI TESTER
(TEST PLUG)
Used in diagnostic checks with
engine management system.
Previously released.
Mandatory
J34730-2C
(BT-8329)
INJECTOR NODE LIGHT
TESTER
Used when carrying out engine
management electrical
diagnostic checks.
Previously released.
Mandatory