If the spark plug deposit indicates black coating of soot, it indicates that the engine has been generally operating on
Too lean mixture
Stoichiometric mixture
Most economical mixture
Too rich mixture
Correct Answer :
D. Too rich mixture
Related Questions
The main task of a battery in automobiles is to
Supply electricity to the alternator
Act as a reservoir or stabilizer of electricity
Supply electricity to the vehicle's electrical system at all times while the engine is running
Supply a large amount of power to turn the starter motor when the engine is being started
If the engine coolant leaks into the engine oil, then engine oil
Appears milky
Become foamy
Turns black
None of these
The petrol engine works on
Otto cycle
Carnot cycle
Diesel cycle
Rankine cycle
The basic purpose of a four wheel drive (4WD) system is that it
Delivers improved cornering on dry road surfaces
Eliminates the need of snow tyres, tyre chains, etc.
Ensures effective transmission of engine torque to all four wheels, even on slippery road surfaces
Ensures that effective braking can be performed, even on slippery surfaces
The fuel that detonates easily, is
N-heptane
Iso-octane
Benzene
Alcohol
The camshaft of a four stroke Diesel engine running at 1000 rpm will run at
500 rpm
1000 rpm
2000 rpm
4000 rpm
The lubrication oil flow in an engine is in the order as
Oil strainer, oil pump, relief valve, oil filter, cylinder block, cylinder head and oil pan
Oil pump, oil strainer, relief valve, oil filter, cylinder block, cylinder head and oil pan
Oil strainer, oil filter, relief valve, oil pump, cylinder block, cylinder head and oil pan
Oil strainer, oil pump, relief valve, oil filter, cylinder head, cylinder block and oil pan
The function of an alternator in an automobile is to
Supply electric power
Converts mechanical energy into electrical energy
Continually recharges the battery
Partly converts engine power into electric power
The basic purpose of tyres is to
Grip the road and provide good traction
Substitute for springs
Act as brake
None of these
The capacity of a battery is usually expressed in terms of
Volts
Amperes
Weight
Ampere hours
The combustion process in a Diesel engine is a
Constant volume process
Constant pressure process
Constant temperature process
Adiabatic process
Damper is also known as
Shock absorber
Torsion bar
Spring
Radius rod
The most commonly used supplementary restraint system (SRS) component is
Seat belt
Brake
Airbag
Steering
The formula for Isooctane is
C8H18
C7H17
C6H18
C7H18
The rigid suspension is beneficial when
It is desired to reduce the unsprung mass
It is desired to have more flexibility in design
It is desired to improve tyre to ground contact characteristics
Large changes in load make it necessary to have a large suspension stroke
Valve overlap is the number of degrees of camshaft rotation during which
Both valves are closed
Both valves are open
Both 'A' and 'B'
None of these
In bias ply tyres
All plies run parallel to one another
Belts of steel mesh are used in the tyres
One ply layer runs diagonally one way and another layer runs diagonally the other way
All of the above
The mechanical efficiency (ηm) of an I.C. engine is equal to (where I.P. = Indicated power, B.P. = Brake power and F.P. = Frictional power)
I.P/B.P.
B.P/I.P.
B.P/F.P.
F.P/B.P.
The function of antilock brake system (ABS) is that is
Reduces the stopping distance
Minimises the brake fade
Maintains directional control during braking by preventing the wheels from locking
Prevents nose dives during braking and thereby postpones locking of the wheels
The engine oil viscosity is defined by _________ ratings.
Automatic transmission fluid (ATF)
Society of automotive engineers (SAE)
Gross vehicle weight (GVW)
American petroleum institute (API)
In a Diesel engine, the fuel is ignited by
An electric spark
The heat of compression
The hot exhaust
None of these
The main merit of a multi cylinder type cylinder sleeve is
Smaller engine dimensions
Better cooling efficiency
High rigidity
None of these
An engine has a clearance volume of 100 cm³ and a swept volume of 800 cm³. The compression ratio is
7 : 1
8 : 1
9 : 1
10 : 1
The negative plates of a lead acid battery has
Lead peroxide (PbO₂)
Spongy lead (Pb)
Lead sulphate (PbSO₄)
Sulphuric acid (H₂SO₄)
In which of the following conditions, the idle CO percentage should be measured with the vehicle?
Headlights and other electrical devices are switched off
Headlights and other electrical devices are switched on
Headlights and other lights are switched off
Headlights are switched on
The specific gravity of acid in a fully charged battery is generally
1.00
1.28
1.82
2.81
Two general types of tyres are
Tube type and tubeless
Solid and tubeless
Air and pneumatic
Split rim and drop centre
In a Diesel engine, the function of a fuel injector is to
Mix the fuel and air
Ignite the air-fuel mixture
Provide flame front for ignition
Spray atomized fuel in the cylinder
The main function of the tread pattern on tyre is that
The tread grooves pass air between the tyre and road surface, thereby preventing tyre from overheating
The crests between the tread grooves absorb road noise
In wet conditions, the tread grooves expel water that is drawn between the tyre and road surface
The tread pattern protects the tyre's inner carcass from small stones and pieces of glass
The caster is called positive when the top of the king pin is inclined to the
Rear of the vehicle
Front of the vehicle
Left of the vehicle
Right of the vehicle