Spark Plug Symptoms
This happens to the engine's idle when spark plugs are worn or dirty.
What is rough and uneven? (or What is the idle becomes rough?)
This is the RPM at which an engine should idle smoothly and steadily.
A) 500 rpm
B) 1000 rpm
C) 1500 rpm
D) 2000 rpm
Answer: B) 1000 rpm
A car won't start even with this and a full tank of fuel if spark plugs are bad.
A) New tires
B) A good battery
C) Clean oil
D) Full coolant
Answer: B) A good battery
This is how often you'll need to fill up your gas tank when spark plugs are damaged.
A) Less often
B) The same as usual
C) More often than usual
D) Never
Answer: C) More often than usual
When inspecting a spark plug, you should look at this part to check for wear.
A) The fuel line
B) The electrode and gap
C) The battery terminal
D) The oil filter
Answer: B) The electrode and gap
This is what the tachometer(RPM) needle does during an engine misfire.
What is jump (or fluctuate)?
This is the part of the engine where the spark plug ignites the air-fuel mixture.
A) Fuel tank
B) Exhaust pipe
C) Combustion chamber
D) Radiator
Answer: C) Combustion chamber
This can drain early from repeated starting attempts when spark plugs are bad.
A) The fuel tank
B) The oil
C) The battery
D) The coolant
Answer: C) The battery
This is what happens to the vehicle during engine surging.
A) It runs smoothly
B) It jerks forward, then slows down
C) It stops completely
D) It accelerates perfectly
Answer: B) It jerks forward, then slows down
This type of buildup on a spark plug can cause ignition problems.
A) Water
B) Carbon, oil, or fuel residue
C) Paint
D) Rust only
Answer: B) Carbon, oil, or fuel residue
This percentage represents how much fuel economy can drop with damaged spark plugs.
A)10%
B) 20%
C)30%
What is 30%?
Correct spark timing helps create these two things in an engine.
A) Heat and noise
B) Maximum power and improved fuel efficiency
C) Smoke and emissions
D) Vibration and speed
Answer: B) Maximum power and improved fuel efficiency
During an engine misfire, this many cylinders fail to ignite properly.
A) None
B) All cylinders
C) One or more cylinders
D) Only the first cylinder
Answer: C) One or more cylinders
This action can quickly restore power and smooth acceleration when spark plugs are the problem.
A) Adding more fuel
B) Changing the oil
C) Replacing the spark plugs
D) Cleaning the battery
Answer: C) Replacing the spark plugs
A healthy spark plug tip should be this color.
A) Black
B) White
C) Tan or gray
D) Red
Answer: C) Tan or gray
This condition occurs when there is too much air or not enough fuel in the mixture, causing the engine to surge or hesitate.
A) Rich condition
B) Lean condition
C) Flooded condition
D) Balanced condition
What is a lean condition?
This is what the spark plug provides to ignite the air-fuel mixture.
A) Heat
B) Pressure
C) A spark or electrical discharge
D) Fuel
Answer: C) A spark or electrical discharge
This happens to emission levels when an engine misfires.
A) They decrease
B) They stay the same
C) They increase
D) They disappear
Answer: C) They increase
A rough idle causes the car to do this more than normal.
A) Run quietly
B) Shake
C) Accelerate
D) Cool down
Answer: B) Shake
This part of the spark plug should NOT have cracks or damage.
A) The threads
B) The insulator
C) The gap
D) The terminal
Answer: B) The insulator
Name THREE symptoms that can indicate bad spark plugs in an engine.
Answer: Any three of: rough idle, trouble starting, engine misfires, engine surging/hesitation, high fuel consumption, lack of acceleration
Explain what happens when spark plugs have wide gaps.
Answer: Worn spark plugs with wide gaps cause incomplete combustion and poor fuel use/efficiency
Why would a lean mixture cause damage to the spark plug tip?
Answer: A lean mixture (too much air, not enough fuel) runs hotter, which can overheat and damage the spark plug tip
What is incomplete combustion and how does it relate to fuel consumption?
Answer: Incomplete combustion is when fuel isn't completely burned in the engine. This wastes fuel and causes high fuel consumption/poor fuel economy
What can spark plugs tell you about how an engine is running?
Answer: Spark plugs can show if the air-fuel mixture is correct, if there's oil burning, if combustion is complete, and the overall health of the engine's ignition system