AUT-262
The rear axle of an FWD car is the preferred jacking point when the rear wheels need to be removed to make rear toe and camber adjustments.
False
Vacuum refers to any pressure that is higher than the earth's atmospheric pressure at any given altitude.
False
When intake air is compressed, its temperature decreases significantly.
False
Which of the following is NOT a characteristic of a turbocharger?
It requires a mechanical connection between the engine and the pressurizing pump.
A speed-density EFI system computer determines the amount of air entering the engine from the ____________________ sensor and engine rpm input signals.
MAP
The higher the altitude, the lower the atmospheric pressure.
True
When performing an alignment the steering angle sensor may require calibration.
True
A CPI (central multiport injection) fuel injection system for a six-cylinder engine has ______.
All the answers are correct.
A catalytic converter may be tested with a ______.
All the answers are correct.
An O-ring at the base of a fuel injector ______.
All the answers are correct.
Fuel injectors may be controlled ______.
All the answers are correct.
The OBD-II EGR system monitor tests the functioning of the EGR system by opening the EGR valve while monitoring the change in ______.
All the answers are correct.
Unequal SAI angles can cause ______.
All the answers are correct.
When cleaning the injectors with a pressurized injector cleaner, prior to starting the engine, ______.
All the answers are correct.
Which of the following is a cause of detonation?
All the answers are correct.
A rich air/fuel mixture is being discussed. Technician A says oxygen content in the exhaust will be high. Technician B says the O 2 sensor voltage will be high. Who is correct?
B only
Technician A checks a PCV valve by sucking air through it with his mouth. Technician B checks a PCV valve by removing the valve from the grommet in the valve cover and placing his finger over the end of the valve to check for vacuum. Who is correct?
B only
Technician A says a small leak in the air duct between the MAF and the throttle body will not cause a driveability problem. Technician B says a small intake manifold leak in a speed density system will not cause a driveability problem. Who is correct?
B only
Which of the following statements is false?
Bent suspension parts may be straightened to correct camber angles
Which sensor synchronizes the firing of the injectors and determines when piston number 1 is on the compression stroke?
CMP (camshaft position sensor)
When the engine is running at peak efficiency, the only gas that is desirable to be at its peak level is ______.
CO2
Which of the following is NOT an engine exhaust pollutant that is changed by the catalytic converter?
CO2
____ is the angle of the steering axis of a wheel from the vertical, as viewed from the side of the vehicle.
Caster
A linear EGR valve contains up to three electric solenoids that are operated directly by the PCM.
False
Aftermarket kits are only used to adjust rear camber and rear toe.
False
All EGR valves can be tested with a vacuum gauge while the engine is idling.
False
Always pressurize the fuel system before disconnecting any fuel system components.
False
When performing a four-wheel alignment, you should check and adjust the front wheel angles before checking and adjusting the rear wheel angles.
False
_____ emissions are caused largely by unburned fuel from the combustion chambers.
HC
Which of the following is NOT a component of a throttle-by-wire system?
IAC motor (idle air control)
A typical four-gas exhaust analyzer does not measure ____ emissions.
NOX
All the following are considered harmful gases EXCEPT:
O2
Which of the following sensors is used to modify the engine's air/fuel mixture based on oxygen in the exhaust?
O2 sensor
Vacuum leaks in speed density systems can be verified by watching the _____ on a scan tool.
O2 sensor cycle
In closed loop, the PCM adjusts the pulse width according to inputs from a variety of sensors,
O2S (oxygen sensor)
The ____________________ system removes blowby gases from the crankcase and recirculates them to the engine intake.
PCV
Only _____ meets the requirements of OBD II regulations.
SFI (sequential fuel injection)
To monitor the vapor purge in most systems, the PCM changes the duty cycle of the purge solenoid while monitoring the ______.
STFT
Bottom-feed injectors used in throttle body injection (TBI) systems are able to use fuel pressures as low as 10 psi.
True
____________________ is the distance comparison between the leading edge and trailing edge of the front tires.
Toe
____________________ is the last alignment angle to be set.
Toe
A PCV valve that is stuck closed or a restricted hose can cause an accumulation of moisture and sludge in the engine.
True
A catalytic converter can be tested with a rubber mallet.
True
A catalytic converter is one of the most effective emission control devices on a vehicle for reducing HC, CO, and NO X emissions.
True
A digital EGR valve contains up to three electric solenoids that are operated directly by the PCM.
True
A good injector makes a rhythmic clicking sound as the injector is energized and de-energized several times each second.
True
The function of the air bypass valve in a modern supercharger is to ______.
allows the supercharger to idle when extra power is not needed
An exhaust ___________________ is one of the valuable diagnostic tools for driveability problems.
analyzer
Technician A says cylinder misfiring causes a significant increase in HC emissions. Technician B says a dirty air filter may cause high CO emissions. Who is correct?
both A and B
Technician A says high engine temperatures reduce HC and CO emissions. Technician B says incorrect ignition timing can increase the production of NO X.Who is correct?
both A and B
Before the EVAP system on an OBD-II vehicle can be pressure tested or smoke tested for leaks, a scan tool must be used to _____.
close the canister vent solenoid
Excessively high HC emissions may be caused by ______.
both A and B
In sequential fuel injection systems, each injector has its own electrical ____________________ circuit and wiring.
driver
The injectors on a modern port fuel injection system receive fuel from the ____________________.
fuel rail
In an intake manifold for a PFI engine, the __________________ serves as a reservoir for the air and is used to distribute the intake charge evenly to the runners and intake ports.
plenum
Which of the following is NOT part of an enhanced (OBD-II) evaporative control system?
thermal vacuum valve (TVV)
A digital EGR valve has up to _____ solenoids.
three
An APP (accelerator pedal position) sensor is found on vehicles with ______.
throttle by wire
Turning the adjustment sleeve on the ____________________ changes the toe setting.
tie-rod
The __________________ is a chart of the vacuum hose routings, vacuum source, and relative component locations for all emissions-related equipment.
vacuum schematic
Do not use compressed ____________________ to flush or clean the fuel rail.
air
After a two wheel alignment, the steering wheel on the vehicle is not centered. Technician A recommends a four wheel alignment to determine whether the rear wheels are parallel to one another and perpendicular to a common centerline. Technician B says if the steering wheel is not centered after an alignment, it should be pulled off the column and correctly positioned. Who is correct?
A only
Fuel trim is being discussed. Technician A says a positive fuel-trim value means the PCM detects a lean mixture and is increasing the pulse width to add more fuel to the mixture. Technician B says LTFT [long-term fuel trim] is erased when the ignition is turned off. Who is correct?
A only
Technician A says an intake manifold vacuum leak may cause a high idle speed. Technician B says a dirty IAC bypass passage will not cause the idle speed to be below specifications. Who is correct?
A only
Technician A says cross caster is the difference between the left-side and right-side caster. Technician B says excessive negative caster can be corrected by moving the upper ball joint, or strut mount, forward. Who is correct?
A only
Technician A says if the distance between the leading edges of the front tires is less than the distance between the trailing edges, then there is toe-in. Technician B says front toe-in is adjusted by adding or removing shims between the upper control arms and the body/frame. Who is correct?
A only
Technician A says the EGR vent solenoid is normally open. Technician B says the EGR control solenoid is normally open. Who is correct?
A only
Technician A says the EVAP monitor for an OBD-II system determines whether there is sufficient purge flow by varying the purge solenoid duty cycle while monitoring change in STFT. Technician B says the canister vent solenoid must be open during the EVAP pressure test portion of the monitor. Who is correct?
A only
Technician A says the engine should idle for 20 to 120 seconds after a hard run to allow the turbocharger shaft to cool. Technician B says if the vehicle has not been driven for a few days, start the engine up and run it at 2,000 to 2,500 rpm to flush the old oil out of the turbocharger bearings and oil lines. Who is correct
A only
Technician A says the main advantage of a turbocharger is that it allows for an increase of power without a substantial decrease in fuel economy. Technician B says the use of exhaust gas to drive the turbocharger robs power from the engine when the vehicle is driven at low speeds. Who is correct?
A only
Technician A says a defective injector may cause cylinder misfiring at idle speed. Technician B says restricted injector tips may result in acceleration stumbles. Who is correct?
both A and B
Technician A says a three-way catalytic converter (TWC) oxidizes carbon monoxide and hydrocarbons into carbon dioxide and water. Technician B says a TWC reduces NO x into nitrogen and carbon dioxide. Who is correct?
both A and B
A three-way catalytic converter (TWC) stores oxygen when the air/fuel ratio is rich.
True
A twin scroll turbocharger uses two turbine wheels connected to a common shaft to improve performance and reduce lag.
True
A vehicle with high caster settings may experience increased shoulder wear on the tires if driven mostly in urban areas.
True
An AIR system should be checked for overall efficiency by looking at the changes in exhaust quality when the system is turned on and off.
True
An alternative to the I/M 240 test is the acceleration simulation mode (ASM) test.
True
An engine in good condition will produce a steady, constant vacuum reading above 15 inches at a warm idle.
True
Diesel engines emit less HC, CO, and CO 2 than spark ignition gasoline engines.
True
Exhaust manifolds for most vehicles are made of cast or nodular iron.
True
Fuel injectors are electromechanical devices.
True
Hydrocarbon and carbon monoxide exhaust emissions are highest when the engine is cold.
True
If the IAC pintle is extended too far, the motor can be damaged during installation.
True
If the PCV valve is stuck in the open position, a lean air/fuel ratio may cause a rough idle or engine stalling.
True
Never turn on the ignition switch when any fuel system component is disconnected.
True
On some models a pop rivet must be removed from the strut mount before a camber adjustment can be made.
True
Other than inspecting the electrical connections, there are usually no physical checks to mass airflow or manifold absolute pressure sensors.
True
SAI (steering axis inclination) helps the vehicle's steering system return to straight ahead after a turn.
True
The engine must be at normal operating temperature before the O 2 sensor is tested.
True
Which of the following statements is false?
Unequal side-to-side SAI will not cause a pull while driving.
Technician A says positive caster will result from excessive toe-in. Technician B says a vehicle may wander as a result of excessive negative caster. Who is correct?
B only
Technician A says the oxygen sensor (O 2S) detects misfires by monitoring the amount of unburned fuel in the exhaust system. Technician B says a heating element inside the sensor allows the sensor to reach operating temperature quickly and to maintain its temperature during periods of idling or low engine load. Who is correct?
B only
Technician A says throttle body cleaner may be used to clean the IAC motor internal components. Technician B says on some vehicles, IAC motor damage can occur if the pintle is cleaned with throttle body cleaner. Who is correct?
B only
Technician A says when the ECT sensor detects low engine temperature, the PCM decreases the injection pulse width. Technician B says when the TP sensor detects a sudden increase in throttle angle, the PCM increases the injectors' pulse width. Who is correct?
B only
Variable intake manifolds for engines with port fuel injection are being discussed. Technician A says at low speeds, the air travels through a short or large diameter runner. Technician B says they deliver more power at high speed. Who is correct?
B only
While discussing EGR systems with a differential pressure feedback EGR (DPFE) sensor, Technician A says the DPFE sensor sends a signal to the PCM in relation to intake manifold pressure. Technician B says the PCM can make corrections to the EGR flow if the actual flow does not match the desired flow. Who is correct?
B only
While discussing PFI systems, Technician A says the PCM provides the proper air/fuel ratio by controlling the fuel pressure. Technician B says the PCM provides the proper air/fuel ratio by controlling the injector pulse width. Who is correct?
B only
While discussing central port injection (CPI), Technician A says the poppet nozzles are opened by the computer. Technician B says the poppet nozzles are opened by fuel pressure. Who is correct?
B only
Technician A says an intake manifold that delivers both air and fuel (carburetor or TBI) is designed to cause turbulence so that the air and fuel mix while they are being delivered to the cylinders. Technician B says in an air only type manifold (PFI) the length of the runners is designed to achieve the best performance during a particular range of engine speeds. Who is correct?
both A and B
Technician A says oil in the PCV filter and air cleaner can occur if the PCV valve is restricted or plugged. Technician B says oil buildup inside the throttle body can be an indication of high crankcase pressure. Who is correct?
both A and B
Technician A says pulsation dampers reduce the pressure pulsations caused by the rapid opening and closing of the fuel injectors. Technician B says the damper helps to reduce fuel noise and maintains pressure during engine cooldown. Who is correct?
both A and B
Technician A says the bearings in a turbocharger are cooled by engine oil. Technician B says turbocharger bearings are cooled by engine coolant. Who is correct?
both A and B
Technician A says the production of CO 2 is directly related to the amount of fuel consumed; therefore, more fuel-efficient engines produce less CO 2. Technician B says imposing new CAFE (fuel economy) standards will, in effect, reduce CO 2 emissions. Who is correct?
both A and B
Technician A says thrust line deviations are usually caused by the shifting of the rear axle on its spring supports. Technician B says rear wheel misalignment or damage from an accident can cause thrust line deviations. Who is correct?
both A and B
Technician A says turbocharging uses the heat energy in the engine's exhaust gases to drive a pump that compresses the intake air. Technician B says supercharging relies on the rotation of the engine to compress the air.
both A and B
Technician A says when CO goes up, O 2 goes down. Technician B says at the stoichiometric point (14.7:1), HC and CO will be at their lowest levels and CO 2 will be at its highest. Who is correct?
both A and B
NO X, HC, and CO are changed into harmless gases by the ____________________ in the three way catalytic converter.
catalyst
A water manometer for testing crankcase pressure/vacuum can be made from a 2 foot length of _____________________.
clear plastic tubing
The I/M 240 test requires the use of a variable inertia weight ____________________.
dynamometer
The ____________________ bolt and cam assembly is often used to adjust camber and caster settings.
eccentric
Heated air inlet systems, manifold heat control valves (heat risers), and EFE heater grids were used on older cars with carburetors and TBI fuel injection to prevent vaporized fuel from condensing inside the ____________________.
intake manifold
The ____________________ cools the turbocharged air before it reaches the combustion chamber.
intercooler
A vehicle is being aligned that has too much positive camber and too little positive caster on the left front wheel. The vehicle has an adjustable strut mount that allows for both caster and camber adjustment. In what direction should the mount be moved?
inward and rearward
The activity of an O2 sensor is best monitored with a ______.
lab scope
While cranking a fuel injected engine and holding the accelerator to the wide-open throttle position, the air/fuel mixture will be ______.
lean
A pulse ____________________ injector uses high current to open the injector.
modulation
Technician A says TBI systems use top fuel-feeding injectors. Technician B says PFI systems use bottom fuel-feeding injectors. Who is correct?
neither A nor B
Technician A says a defective throttle position (TP) sensor will not affect the EGR valve operation. Technician B says a defective engine coolant temperature (ECT) sensor will not affect the EGR valve operation. Who is correct?
neither A nor B
A(n) ____________________ is used to test the internal electrical circuit of an injector.
ohmmeter
Boost pressure is measured with a pressure gauge ______.
on a road test at full throttle
The first time the OBD-II system monitor detects a fault in the system, a ___________________ DTC is set. This will not cause the MIL light to illuminate and will self-erase if the monitor passes on the next trip.
pending
Which problem is not caused by excessive positive caster?
poor steering return
The ____________________ helps to maintain constant fuel pressure, reduces fuel noise, and maintains pressure during engine cool down.
pulsation damper
Many vehicles are designed to use ____________________ of various thicknesses to adjust camber and caster settings.
shims
Which of the following should NOT be used to lubricate injector O-rings?
silicone grease
A fuel injection system that uses a MAP sensor [manifold absolute pressure] to determine the amount of air entering the engine is called a _____-type injection system.
speed density
A stuck open EGR valve could cause _____.
stalling
The IAC system uses a ____________________ motor to retract or extend the IAC valve.
stepper
If a catalytic converter in a late model vehicle is not working properly, the ______________________ will turn on.
MIL
A vehicle with excessively high fuel pressure is being diagnosed. Technician A says the problem could be a restricted fuel return line. Technician B says the problem could be a shorted (closed) fuel pump relay. Who is correct?
. A only
Idle learn procedures for ETC (throttle-by-wire)-equipped vehicles are being discussed. Technician A says the learn or relearn procedure should be completed anytime the PCM has been replaced or updated, or after the throttle body has been cleaned or replaced. Technician B says the system does not need to relearn if the battery has been disconnected. The system will automatically go through the procedure when the engine is restarted.Who is correct?
. both A and B
Technician A says HC emissions are caused by incomplete combustion. Technician B says an excessively lean air/fuel mixture may result in cylinder misfiring and high HC emissions. Who is correct?
. both A and B
Technician A says higher than normal idle speed may be caused by an air-conditioning switch that is always closed. Technician B says higher than normal idle speed may be caused by a defective engine coolant temperature sensor. Who is correct?
. both A and B
An intercooler can reduce the temperature of the inlet air as much as __________________ degrees Fahrenheit.
150
NO X emissions are caused by nitrogen and oxygen uniting at cylinder temperatures above ______.
2,500°F (1,371°C)
EGR flow is disabled during throttle openings greater than ___________________ percent
50
Technician A says all vehicles with strut suspension have caster adjustments. Technician B says caster is the first angle checked during a two-wheel alignment. Who is correct?
B only
Technician A says if a lean condition caused by a vacuum leak, restricted injectors, dirty MAF, clogged fuel filter, or bad fuel pump exists, the LTFT will have a negative number. Technician B says when the O2 sensor has a rich signal, the STFT goes lean to adjust the air/fuel ratio. Who is correct?
B only
Technician A says if caster at both wheels is not equal, the vehicle will tend to drift toward the side with the most positive caster. Technician B says if camber is not the same on both wheels, the vehicle will pull toward the side with the most positive camber. Who is correct?
B only
Technician A says if the EGR valve does not open, the engine may emit excessive amounts of HC. Technician B says if the EGR valve does not open, the engine may detonate on acceleration. Who is correct?
B only
Technician A says in a returnless fuel system, the pressure regulator is mounted on the fuel rail. Technician B says in a returnless fuel system the pressure regulator, fuel sender, and pump assembly are combined in one unit inside the fuel tank. Who is correct?
B only
An ignition misfire can cause excessive carbon monoxide emissions in the exhaust.
False
Because modern engines heat up rapidly, heated oxygen sensors (HO 2S) are not needed.
False
Electric turbochargers are standard equipment in some newer vehicles.
False
Generally, an engine designed for maximum torque and horsepower at high speeds has longer runners than one that provides high torque at lower speeds.
False
Low CO indicates a lean mixture; as the mixture becomes more lean, HC increases.
False
Superchargers are normally lubricated by engine oil through passages in the intake manifold.
False
The auxiliary air valve is controlled by the PCM.
False
The exhaust analyzers used in I/M 240 measure the emissions levels in ppm.
False