1. Faulty valve guide
2. Worn piston ring
3. Cracked piston ring land
4. Oil leaking into the combustion chamber
5. Defective air filter
6. Plugged catalytic converter
Recommendations:
1. Inspect the valve train for signs of damage or wear. Replace any faulty valve guide or seals.
2. Examine the piston rings for signs of wear, damage, or improper installation. Replace any damaged or worn piston rings.
3. Look for evidence of cracked piston ring lands. If found, the engine may need to be rebuilt or replaced.
4. Inspect the oil control ring for signs of sticking, clogging, or damage. Clean or replace the oil control ring if necessary.
5. Replace the air filter with a clean one.
6. Check the catalytic converter for any signs of clogging, damage, or other issues. If the catalytic converter is clogged or damaged, it may need to be replaced.
