2417: Chapters 5-8

Technician A says the exhaust gas from the cylinders of a turbocharged engine is directed past the turbine wheel. Technician B says the exhaust gas from the cylinders of a turbocharged engine is directed past the compressor wheel.

A

Technician A says the fuel rail delivers fuel to the fuel injectors. Technician B says the throttle body in a port fuel injection system controls the amount of fuel entering the engine.

A

Technician A says the poppet nozzles in the CMFI system are opened by fuel pressure. Technician B says the computer opens the poppet nozzles in the CMFI system.

A

Technician A says the powertrain control module provides the proper air-fuel ratio by controlling injector pulse width. Technician B says the powertrain control module controls the fuel pressure to provide the proper air-fuel ratio.

A

Which of the following fuel systems can have fuel pressure of over 1500 psi?

GDI

The three major automotive pollutants are

HC, CO, NOx

A burn-off relay may be used with which sensor?

MAF sensor

Technician A says any induction air leak after the MAF sensor can cause a poor running condition. Technician B says an air leak after the MAF sensor results in un-metered air.

both

Technician A says fuel that has low volatility can cause a buildup of deposits in the combustion chamber. Technician B says liquid gasoline will not burn.

both

Technician A says if the IAC value is at or near zero on a speed density system there may be a manifold vacuum leak. Technician B says if the IAC value is to high there may be a build-up of carbon on the backside of the throttle plate.

both

Technician A says low fuel pressure may be caused by a restricted fuel filter. Technician B says when testing fuel pressure make sure the specifications are either for the engine running or the engine off.

both

Technician A says placing the turbocharger close to the exhaust helps its efficiency. Technician B says the turbocharger shaft may turn at speeds in excess of 100,000 rpm.

both

Technician A says to relieve pressure on an EFI system, a pressure gauge may be connected to the fuel pressure test port and the bleed valve on the gauge opened with the bleed hose installed in an approved container. Technician B says before fuel system components on an EFI system can be removed, the fuel system pressure must be relieved.

both

An air filter that is contaminated with oil may be cause by

both A and B

High fuel pressure may be caused by:

both A and B

The computer uses the TP sensor to

both A and B

An O2 sensor may be used to

both A and C

Oil is found in the air filter housing. What is the most likely cause?

both A and C

An engine stalls during tight parking maneuvers. Which is the most likely cause?

defective power steering switch

Octane is use to reduce:

detonation

The purpose of the manifold vacuum connection to the fuel pressure regulator is to:

enrichen the air/fuel ratio under wide open throttle conditions

Higher than normal reference voltage is recorded at a sensor. Which is the most likely cause?

excessive resistance in the voltage reference ground circuit

Oxides of nitrogen are caused by

high cylinder temperature

An IAC valve stuck in the closed position may cause all of the following except:

high idle speed

When the pressure in the intake manifold increases, the fuel pressure regulator on a port fuel injection system:

increases the fuel pressure

With gasoline direct injection the fuel is injected:

into the combustion chamber

A partially restricted or blocked exhaust system may result in:

loss of engine power

A breakout box is used to

monitor signals received by the computer

Technician A says fuel injectors may be cleaned by soaking them in solvent. Technician B says it is a good idea to use a wire brush to unclog injectors.

neither

To help isolate a clogged or dirty injector:

perform an injector balance test

Piezoresistive sensors measure

pressure and mechanical strain

In any fuel injection system the fuel pressure must be high enough to:

prevent the fuel from boiling

Which of the following can be used to locate both exhaust and vacuum leaks?

smoke

Which of the following emissions are specific to diesel engines?

soot

Excessive oxygen in the exhaust gas stream will cause a zirconia oxygen sensor to

stay below 450mV

The oxygen sensor that changes current flow to indicate exhaust oxygen content is the

air/fuel ratio sensor

A defective engine coolant temperature may cause

all of the above

A turbocharger may be damaged by

all of the above

Magnetic pulse generators can be checked by which of the following

all of the above

The computer may use the manifold absolute pressure sensor to

all of the above

The intake manifold tuning valve makes the intake manifold:

all of the above

Turbo lag may be referred to as

all of the above

When a computer has adaptive strategy, a short learning period will be necessary when:

all of the above

Which component is responsible for creating engine vacuum?

all of the above

While accessing diagnostic trouble cods on a pre-OBD II vehicle,

all of the above

The fuel pressure regulator in a returnless fuel system is located:

at the fuel pump sender assembly

Technician A says a SFI requires both crank and cam position sensors. Technician B says SFI engines can also function as MFI if necessary.

both

Technician A says a reducing catalyst takes NOx and converts it into N2 and O2. Technician B says the O2 released from the NOx in the reducting catalyst is used to help oxidize the CO and HC.

both

Technician A says acceleration stumbles may be the result of restricted injector tips. Technician B says cylinder misfiring at idle speed may be caused by a defective injector.

both

Technician A says an engine with an intake manifold vacuum leak may misfire at idle and lower engine speeds. Technician B says a faster-than-normal idle speed in a fuel-injected engine may be caused by an intake manifold vacuum leak.

both

At 2,000 RPM, the maximum allowable exhaust back pressure is approximately

1.2 psi

Technician A says a fast idle thermo valve controls air intake based on temperature. Technician B says The fast idle thermo valve may be disassembled and adjusted.

A

Technician A says a rich air-fuel mixture may be the result of higher-than-normal fuel pressure. Technician B says higher-than-normal fuel pressure causes a lean air-fuel ratio.

A

Technician A says a speed density EFI system is one in which the computer calculates the amount of air entering the engine. Technician B says that to determine the air entering the engine in a speed-density system, the computer uses the TPS and ECT signals.

A

Technician A says fuel pumps can be checked for amperage draw and current waveform. Technician B says a low amp probe is connected in series with the circuit being tested.

A

Technician A says higher fuel pressure at wide-open throttle is the result of low manifold vacuum to the pressure regulator in the SFI system. Technician B says higher fuel pressure at wide-open throttle is maintained by the PCM in the SFI system to enrichen the air/fuel ratio for better acceleration.

A

Technician A says in a central port injection system fuel pressure ranges from 54 to 64 psi. Technician B says fuel pressure in a port fuel injection system is typically higher than fuel pressure in a central port injection system.

A

Technician A says an injector ohm test is the most accurate method of testing a fuel injector's operation. Technician B says an injector ohm test can only confirm a defective injector winding.

B

Technician A says coolant is routed through the throttle body to warm the incoming air. Technician B says the throttle body is warmed by coolant to prevent it from freezing.

B

Technician A says oxides of nitrogen are changed to carbon dioxide and water by a three-way catalytic converter. Technician B says hydrocarbons and carbon monoxide are changed to carbon dioxide and water by a two-way catalyst.

B

Technician A says reducing spark advance can cause spark knock. Technician B says excessive carbon deposits can cause spark knock.

B

Technician A says that if the engine stalls and the ignition switch is on, the one-way check valve prevents fuel flow from the pump to the fuel filter and fuel system. Technician B says that when the engine is shut off, the one-way check valve prevents fuel flow from the underhood fuel system components into the fuel pump and tank.

B

Technician A says the PCM supplies power and ground to magnetic pulse generators. Technician B says the PCM supplies power and ground to Hall-effect sensors.

B

A low voltage signal from the O2 sensor indicates

a lean air fuel ratio

All are advantages of GDI systems except:

additional NOx emissions

Short-term fuel trim (STFT) adds or subtracts fuel to correct for

both B and C

The result of a plugged catalytic converter can cause an exhaust restriction which will in turn cause

both B and C

Multiport fuel injection systems do not require a:

camshaft position sensor

Throttle body fuel injection systems provide improved fuel metering when compared to

carburetors

Diesel fuel may be blended to improve

cold starting

An intercooler is used to:

cool the air from a supercharger or turbocharger before it reaches the combustion chamber

The supercharger is driven by

crankshaft

A thermistor is a solid-state variable resistor made from a semiconductor material that changes resistance in relation to

temperature changes

All of the following are added to gasoline except?

tetraethyl lead

Injector pulse width is:

the amount of time the injector is held open and injecting fuel

Magnetic pulse generators are commonly used to send data to the computer about

the speed of monitored component

The acceptable amount of alcohol mixed with gasoline is:

up to 10%

All of the following are types of mass air flow sensors except

variable reluctance-type sensor

Which of the following is not an advantage of natural gas fueled vehicles?

wide availability of CNG

The fuel pressure regulator in a returnless fuel system is located:

with the fuel pump module