Misfire In One Cylinder
Checking The Spark Plugs
- Remove all the spark plugs.
- Is the spark plug for the relevant cylinder lighter in color than the other plugs?
Yes:
^ Proceed to test step below.
No:
^ Proceed to Checking Compression section below.
Replacing Component
- This indicates that the cylinder is receiving too little fuel.
- Try a new fuel injector.
Then proceed to test step below
Checking Compression
- Carry out a compression test.
- Is compression correct?
Yes:
^ Proceed to test step below.
No:
^ Remedy as necessary,then replace all spark plugs. It is very important that the correct spark plugs are used, see replacement part catalogues for P/N. Check the spark gap on the new spark plugs before installing them. The spark gap should be 0.7 - 0.8mm.
^ Then proceed to Verification section below.
Checking Cooling System
- Connect pressure tester 998 5496 to the expansion tank. Pump up a pressure of approx. 100 kPa. Shine a flashlight into the relevant cylinder and check that there is no leakage between the cooling system and the cylinder.
If reading is OK:
^ Proceed to test step below.
If reading is incorrect:
^ Remedy as necessary, then replace all spark plugs. It is very important that the correct spark plugs are used, see replacement part catalogues for P/N. Check the spark gap on the new spark plugs before installing them. The spark gap should be 0.7 - 0.8mm.
^ Then proceed to Verification section below.
Checking Ignition Cables
- Remove all ignition cables Check ignition cables for damage, cracking and flashover.
- Then measure the resistance in each ignition cable. Resistance should be 1.5 - 4.5K ohms depending on their length, at +20°C.
- Replace ignition cables that are damaged or have an in correct resistance.
- Check between ignition cables and the distributor cap and sparkplugs for loose connections.
- Remedy if necessary.
Then proceed to test step below.
Checking Distributor Cap And Rotor
- Remove distributor cap.
- Check distributor cap/rotor for damage, cracking and flashover.
- If faults are suspected clean and replace damaged components as necessary.
Then proceed to test step below.
Checking Flywheel/Pulse Wheel
- Install new spark plugs.
NOTE: It is very important that the correct spark plugs are used, see replacement part catalogues for P/N. Check the spark gap on the new spark plugs before installing them. The spark gap should be 0.7 - 0.8mm.
- Install distributor cap and connect all ignition cables.
- Start the engine and idle it.
- Go into diagnostic trouble code (DTC) parameter list.
- Read off flywheel adaption values B, C, D and E.
- Values should be between -0.391 and +0.387.
If reading is OK:
^ Proceed to test step below.
If reading is incorrect:
^ Check engine speed (RPM) sensor probe and the hole to the flywheel/carrier plate for damage, scratches and warp. If the engine speed sensor and hole are OK: Try a new flywheel, reset adaption.
^ Then proceed to Verification section below.
Checking Injector Cables And Terminals
- Check the cable between the injector and engine control module (ECM) for an intermittent open-circuit, intermittent short-circuit to ground and an intermittent short-circuit to supply voltage.
- Check injector and engine control module connectors for loose connections, contact resistance and oxidation.
Then proceed to test step below.
Checking For Air Leakage
- Check for air leakage.
- If air leakage occurs remedy as necessary.
Then proceed to test step below.
Checking Fuel And Residual Pressure
- Check fuel and residual pressure.
Then proceed to test step below.
Verification
- After carrying out the repair, check that the fault has been remedied as follows.
- Ignition off.
- Ignition cables and connectors connected. Fuel line connected.
- Write down frozen values for all misfire codes if this has not been done.
- Erase diagnostic trouble codes.
- Go into the scrolling values list and check that the flywheel has been adapted. If the flywheel has not been adapted this must be carried out by engine braking in a low gear so that the fuel shut-off system operates. Do this a few times so that flywheel adaptation switches to completed.
- Test drive the car. Use the frozen values to attempt to recreate the driving conditions when the diagnostic trouble code was stored. This applies to engine speed engine coolant temperature (ECT) and load especially. Use the scrolling values list.
- There should not be any codes.
If reading is OK:
^ Fault corrected
If reading is incorrect:
^ Proceed to test step below.
Fault-tracing Information
- The verification result shows that the fault persists.
- Do you want to exit fault-tracing?
Yes:
^ Fault not corrected
No:
^ Return to Checking The Spark Plugs section above.