Question

question 10 (5 points) listen which one of the following determines the ability of a diesel engine to start at low temperatures, providing smooth warm - up and even combustion? a) cloud point b) cetane rating c) specific gravity rating d) sulfur content question 11 (5 points) listen the operation of the waste - spark ignition system is being discussed. technician a says the spark that occurs on the exhaust stroke is called the \waste spark\ because it does no useful work, being used only as a voltage path for the secondary winding of the ignition coil. technician b says even if theres only one defective spark plug wire or spark plug, two cylinders may be affected. who is correct? a) technician a b) technician b c) neither technician a nor b d) both technicians a and b

Explanation:

Question 10

• Option A (Cloud point): The cloud point is the temperature at which wax in diesel fuel starts to crystallize, affecting fuel flow but not directly engine start or combustion smoothness.
• Option B (Cetane rating): Cetane rating measures diesel fuel's ignition quality. Higher cetane means easier ignition, better cold starting, smooth warm - up, and even combustion.
• Option C (Specific gravity rating): Specific gravity relates to fuel density, not ignition or combustion characteristics for cold start.
• Option D (Sulfur content): Sulfur content affects emissions and corrosion, not engine start or combustion smoothness.

• Technician A: In a waste - spark ignition system, the spark on the exhaust stroke is the “waste spark” as it doesn't contribute to combustion (no useful work) and only provides a voltage path for the ignition coil's secondary winding. This is correct.
• Technician B: In a waste - spark system, each coil fires two cylinders (one on compression, one on exhaust). So, a defective spark plug wire or plug can affect two cylinders. This is also correct.

Answer:

B) Cetane rating

Question 11