Misfire isolated to cylinder 4. On the 981 flat-six, cylinders 4-6 form Bank 2.
SYMPTOMS
- Flashing or steady check-engine light
- Rough idle
- Hesitation
- Vibration
LIKELY CAUSES
- Faulty coil or plug on cylinder 4
- Failed injector
- Low compression
- Local intake leak
DIAGNOSIS STEPS
- Swap coil and plug to an adjacent cylinder; see if misfire follows
- Test injector
- Compression/leak-down test
RELATED PARTS
- Ignition coil
- Spark plug
- Fuel injector