DTC 5-4-2
5-4-2 MISFIRE MORE THAN 1 CYLINDERPreconditions for DTC
^ If the ECM registers more than approx. 6 - 50% misfiring during 1000 engine revolutions (2500 ignition sequences), the ECM will check if this misfiring comes from one specific cylinder or from different cylinders.
^ If only one cylinder exceeds the limit, DTC 5-4-3 is set first, followed by one of DTCs 4-5-1, 4-5-2, 4-5-3, 4-5-4 or 4-5-5 depending on the relevant cylinder.
^ If several cylinders exceed the limit, DTC 5-4-3 and 5-4-2 are set as well as a DTC for the relevant cylinder.
Substitute value
^ Fuel trim with rear Heated Oxygen Sensor (HO2S) shut off.
Fault sources:
^ Defective spark plugs, ignition cables, distributor cap/rotor, ignition coil or flywheel/tooth wheel.
^ Faulty spark plug.
^ Blocked/leaking injector.
^ Uneven compression.
^ Leakage between cooling system and cylinder.
^ Moisture, flashover in ignition system's high-tension section.
^ Intermittent break, intermittent short circuiting to ground, intermittent short circuiting to voltage supply, contact resistance or loose connection in ignition system's low-tension section, in injector circuit or fuel pump circuit.
^ Too much engine oil.
^ Air leakage.
^ Fuel pressure and residual pressure.
Fault sources not included in the fault tracing process, but which may still set a DTC:
^ Fuel stoppage.
^ Insufficient fuel level, resulting in fuel starvation.
^ Water in the spark plug recesses.
^ Incorrect fuel or dirty fuel.
^ Repeated cold starts whereby the engine is never given sufficient time to reach normal operating temperature between each start.
^ Puncture in a front tire.
Fault symptoms
^ Engine does not start, or is difficult to start.
^ Engine runs unevenly at idling speed, or jerks severely while driving.
^ Poorer performance.
^ Higher emissions.
TESTING PROCEDURE
Other DTCs
^ Read off other DTCs.
If any other DTC is stored (apart from the misfiring codes), it can be assumed that the DTC/DTCs for misfiring are set as a result of the other fault.
If any other DTC is stored:
- Fault tracing as per the relevant DTC.
If no other DTC is stored:
- Check the misfiring codes.
Checking Misfiring Codes
^ Read off the other misfiring codes.
If DTC 5-4-2 and/or DTC 5-4-4 is stored, this means that misfiring has occurred in more than one cylinder.
For, Misfiring in one cylinder:
- Proceed to: MISFIRING IN ONE CYLINDER section below.
For, Misfiring in several cylinders:
- Proceed to: MISFIRING IN SEVERAL CYLINDERS section below.
MISFIRING IN ONE CYLINDER
Checking the Spark Plugs
^ Remove all the spark plugs.
^ Check if the spark plug for the relevant cylinder is lighter in color than the other plugs.
If it is lighter in color than the other spark plugs:
- This means that the relevant cylinder is receiving too little fuel.
- Test with a new fuel injector.
- Then continue with: Checking of compression.
If the spark plug is the same color as all the others:
- Check the compression.
Checking the Compression
^ Carry out a compression test.
If the compression in the relevant cylinder is OK:
- Check the cooling system.
If the compression in the relevant cylinder is incorrect:
- Rectify as necessary, then replace all spark plugs.
NOTE: It is vital that the correct spark plugs are used. Check also the spark gap on the new plugs before fitting them. The gap should be 0.7 - 0.8 mm.
Checking the Cooling System
^ Connect pressure tester P/N 9985496 to the expansion tank.
^ Pump up a pressure of approx. 100 kPa (14.5 psi).
^ Shine a flashlight into the relevant cylinder and check that there is no leakage between the cooling system and the cylinder.
If there is no leakage:
- Check the ignition leads.
If there is leakage:
- Rectify as necessary, then replace all the spark plugs.
Checking the Ignition Leads
^ Remove all ignition leads.
^ Check the ignition leads for signs of damage, cracks and flashover.
^ Then measure the resistance in each ignition lead.
Resistance should be 1.5 - 4.5K ohms depending on length, at +20°C (68°F).
^ Replace those ignition leads which are damaged or have incorrect resistance.
^ Check also that there is no loose connection between the ignition leads and distributor cap and between the ignition leads and spark plugs.
- Rectify as necessary.
- Then continue with: Checking the distributor cap and rotor.
Checking the Distributor Cap and Rotor
^ Remove the distributor cap.
^ Check the distributor cap/rotor for signs of damage, cracks and flashover.
If you suspect a fault:
- Clean, if necessary replace those components which may be damaged.
- Then continue with: Checking the flywheel/tooth wheel.
Checking the Flywheel / Tooth Wheel
^ Fit new spark plugs.
NOTE: It is vital that the correct spark plugs are used. Check also the spark gap on the new plugs before they are fitted. The gap should be 0.7 - 0.8 mm.
^ Install the distributor cap and connect all ignition leads.
^ START the engine and let it run at idling speed.
^ Look up the DTC parameter list.
^ Read off the values on the flywheel adaption B, C, D and E.
The readings should be -97 to +97.
If readings are OK:
- Check the leads and connectors of the relevant injector.
If any of the readings are incorrect:
- Check the RPM sensor's tip and the hole down by the flywheel connecting flange for signs of damage, scratches and metal particles.
If the RPM sensor and hole are OK:
- Test with a new flywheel, reset the adaption.
Checking the Leads and Connectors of the Relevant Injector
^ Check the lead between the relevant injector and ECM for signs of an intermittent break, intermittent short circuiting to ground and intermittent short circuiting to voltage supply.
^ Check also the connector for the relevant injector and the ECM connector for signs of loose connection, contact resistance and oxidation.
- Rectify as necessary.
- Then continue with: Checking for air leakage.
Checking for Air Leakage
^ Check if there is any air leakage.
If there is no air leakage:
- Check the fuel and residual pressure.
If there is air leakage:
- Rectify as necessary.
- Then continue with: Checking of fuel and residual pressure.
Checking Fuel and Residual Pressure
^ Check fuel and residual pressure.
MISFIRING IN SEVERAL CYLINDERS
Checking the Compression
^ Remove all spark plugs.
^ Carry out a compression test.
If the compression is OK:
- Check the cooling system.
If the compression is uneven:
- Rectify as necessary, then replace all spark plugs.
Checking the Cooling System
^ Connect pressure tester P/N 9985496 to the expansion tank.
^ Pump up a pressure of approx. 100 kPa (14.5 psi).
^ Shine a flashlight into each cylinder and check that there is no leakage between the cooling system and cylinders.
If there is no leakage:
- Check the ignition leads.
If there is a leak:
- Rectify as necessary, then replace all the spark plugs.
Checking the Ignition Leads
^ Remove all the ignition leads.
^ Check the ignition leads for signs of damage, cracks and flashover.
^ Then measure the resistance in each ignition lead.
Resistance should be 1.5 - 4.5K ohms depending on length, at +2O°C (68°F).
^ Replace all ignition leads which are damaged or have incorrect resistance.
^ Check that there is no loose connection between the ignition leads and distributor cap, ignition leads and spark plugs and between the ignition lead and coil.
- Rectify as necessary.
- Then continue with: Checking the distributor cap and rotor.
Checking the Distributor Cap and Rotor
^ Remove the distributor cap.
^ Check the distributor cap/rotor for signs of damage, cracks and flashover.
If a fault is suspected:
- Clean, if necessary replace those parts which may be damaged.
- Then continue with: Checking the ignition coil's primary winding.
Checking the Ignition Coil's Primary Winding
^ Switch Ignition OFF.
^ Disconnect the cable terminal from ignition coil connector 15.
^ Connect an ohmmeter between the primary winding's two connectors (1 and 15).
The ohmmeter should show 0.5 - 1.5 ohms at +2O°C (68°F).
If reading is OK:
- Check the ignition coil's secondary winding.
If reading is incorrect:
- Test with a new ignition coil.
- Then continue with: Checking the voltage drop.
Checking the Ignition Coil's Secondary Winding
^ Switch Ignition OFF.
^ Disconnect the ignition coil's high-tension lead.
^ Connect an ohmmeter between connector 15 and the high-tension connector on the ignition coil.
The ohmmeter should show 8 - 9K ohms at +2O°C (68°F).
If reading is OK:
- Check the voltage drop.
If reading is incorrect:
- Test with a new ignition coil.
- Then continue with: Checking the voltage drop.
Checking the Voltage Drop
^ Fit new spark plugs.
^ Install the distributor cap and connect all ignition leads.
^ Connect the cable terminal to the ignition coil.
^ START the engine and let it run at idling speed.
^ Connect a voltmeter between ignition coil connector 15 and ground.
The voltmeter should show battery voltage.
If reading is OK:
- Check the power stage ground connector.
If reading is incorrect:
- Check the voltage supply connectors at the junction box, relay 2/31 and battery positive terminal for signs of loose connection, contact resistance and oxidation.
- Then continue with: Checking the power stage ground connector.
Checking the Power Stage Ground Connector
^ Switch Ignition OFF.
^ Wait for about 150 seconds.
^ Disconnect the power stage.
^ Connect an ohmmeter between power stage connector 1 and ground.
The ohmmeter should show approx. 0 ohms.
If reading is OK:
- Check the power stage leads and connectors.
If reading is incorrect:
- Check the power stage ground connector 31/52 for signs of contact resistance and oxidation.
- Then continue with: Checking the power stage leads and connectors.
Checking the Power Stage Leads and Connectors
^ Check the leads between the following components for signs of an intermittent break, intermittent short circuiting to ground and intermittent short circuiting to voltage supply:
- Power stage connector 4 and ECM B11.
- Power stage connector 1 and ground connection 31/52.
- Power stage connector 3 and battery positive terminal.
^ Check also the following connectors for signs of loose connection, contact resistance and oxidation:
- Power stage.
- ECM.
- Electrical distribution unit.
- Relay 2/31.
- Battery positive terminal.
- Ground connection 31/52.
- Rectify as necessary.
- Then continue with: Checking the flywheel/tooth wheel.
Checking the Flywheel / Tooth Wheel
^ START the engine and let it run at idling speed.
^ Look up the DTC parameter list.
^ Read off the values on flywheel adaption B, C, D and E.
The readings should be -97 to +97.
If readings are OK:
- Check the injectors' current supply.
If any of the readings are incorrect:
- Check the RPM sensor's tip and hole down by the flywheel/connecting flange for signs of damage, scratches and metal shavings.
If the RPM sensor and hole are OK:
- Test with a new flywheel, reset the adaption.
Checking the Injectors' Current Supply
^ Check the leads between the injectors' connector 1 and the main relay (2/32) connector 3, as well as ECM A41 and main relay (2/32) connector 1 for signs of an intermittent break.
^ Check also the connectors at the injectors, main relay (2/32) and ECM for signs of loose connection, contact resistance and oxidation.
- Rectify as necessary.
- Then continue with: Checking the fuel pump's leads and connectors.
Checking the Fuel Pump Leads and Connectors
^ Check the leads between the following components for signs of an intermittent break, intermittent short circuiting to ground and intermittent short circuiting to voltage supply:
- ECM B27 and fuel pump relay connector 4.
- Fuel pump relay connector 2 and ground connection 31/51.
- Battery positive terminal and fuel pump connector 1.
- Fuel pump relay connector 3 and fuel pump connector 1.
- Fuel pump connector 2 and ground connection 31/48.
^ Check also the connectors at the following components for signs of loose connection, contact resistance and oxidation:
- ECM.
- Fuel pump relay.
- Ground connection 31/51.
- Electrical distribution unit.
- Relay 2/31.
- Battery positive terminal.
- Connectors 24/2 and 24/4.
- Fuel pump connector C/BA and ground connection 31/48.
- Rectify as necessary.
- Then continue with: Checking air leakage.
Checking the Air Leakage
^ Check if there is any air leakage.
If there is no air leakage:
- Check the engine oil level.
If there is air leakage:
- Rectify as necessary.
- Then continue with: Checking the engine oil level.
Checking the Engine Oil Level
^ Switch Ignition OFF.
^ Check the engine oil level.
The oil level should be between the min. and max. markings.
If the oil level is OK:
- Check the fuel and residual pressure.
If the oil level is incorrect:
- Top up to correct oil level.
- Then continue with: Checking the fuel and residual pressure.
Checking the Fuel and Residual Pressure
^ Check the fuel and residual pressure.