Ch. 73-75, 79-81, 76-78

typical TP sensor voltage at idle is about

0.5 volt or 10% of WOT sensor voltage

the IAT is being tested. after the vehicle has been allowed to cool for several hours, a scan tool is used to observe the IAT, and compare it to the engine coolant temperature (ECT). The two temperatures should be within how many degrees F of each other

5

the fuel injectors used on a gasoline direct injection system are pulsed using what voltage

50-90 V

which of these is the fuel pump

D

after a TP sensor has been tested using the min/max function on a DMM, a reading of 5 volts is displayed. what does this reading indicate

both b and c are possible: the TP sensor signal is shorted to 5 volt reference and the TP sensor is shorted

a lack of power from an engine equipped with gasoline direct injection could be due to

both b and c: carbon on the injectors and carbon on the intake valves

a P0102 DTC is being discussed. tech a says that sensor circuit shorted to ground can be the cause. tech b says that an open sensor voltage supply circuit could be the cause. who's right

both techs

tech a says that MAP sensors use a 5 volt reference voltage from the PCM. tech b says that the MAP sensor voltage will be higher at idle at high altitudes compared to when the engine is operating at near sea level. who's right

both techs

tech a says that fuel pressure regulators are often located on the return side of the fuel rail. tech b says that the fuel pressure regulator is located at the fuel tank on vehicles using mechanical returnless systems. who's right

both techs

tech a says that most fuel injection systems use the PCM to control the pulsing of the fuel injectors. tech b says that most fuel injection systems use the PCM to control the operation of the fuel pump relay. which tech is correct

both techs

which sensor has the greatest influence on injector pulse width besides the MAF sensor

TP

a typical TP sensor registers about how many volts at WOT (wide open throttle)

4.5

GDI fuel injectors operate under a pressure of about

500-2900 PSI

the first fuel filter in the sock inside the fuel tank normally filters particles larger than

70-100 microns

which statement is false

Absolute pressure is equal to barometric pressure plus intake manifold vacuum

which sensor is used to measure manifold vacuum

MAP

the sensor that measures the temperature of the air being drawn into the engine is called a(n)

both a and b: NTC thermistor and IAT

as the load on an engine increases manifold vacuum decreases and the manifold absolute pressure

increases

if it tripped, which type of safety device keeps the electric fuel pump from operating

inertia switch

the 4 basic computer functions include

input, processing, storage, and output

where is the fuel pump located on most vehicles today

inside the fuel tank

what determines the amount of fuel injected when an injector opens

length of time the injector is open

all of the following are disadvantages of gasoline direct injection EXCEPT

less need for extra fuel for acceleration

when the fuel pressure regulator is deactivated, the fuel pressure defaults to

low pressure mode

refer to this diagram of a fuel pump control circuit. what type of a driver is used in this circuit

low-side driver circuit

which of these is NOT a purpose or function of the MAP sensor

measures engine speed

what type of circuit is shown in this schematic

negative temperature coefficient (NTC) thermistor circuit

a technician attaches one lead of a digital voltmeter to the ground terminal of the TP sensor and the other meter lead to the negative terminal of the battery. the ignition is turned on, engine off, and the meter displays 37.3 mV. tech a says this is the signal voltage and is a little slow. tech b says the TP sensor ground circuit has excessive resistance. who's right

neither techs

what prevents the fuel pump inside the fuel tank from catching the gasoline on fire

no air is around the motor brushes

when testing the ECT sensor with the disconnected, the technician should select what position on the DMM

ohms

which one of these seniors is NOT used to determine injector pulse width during open loop mode

oxygen sensor

dampeners are used on some fuel rails to

reduce noise

why are some fuel rails rectangular in shape

reduces noise

when testing a MAP sensor, the tech should first check the ____ voltage

reference

GDI high pressure fuel lines must be _____ once they are removed for service

replaced

which type of port fuel injection fires each injector separately, following the engine firing order

sequential fired

which wire on a typical TP sensor should back probed to check the voltage signal to the PCM

signal wire

which type of port fuel injection fires all the injectors at the same time, once per crankshaft revolution

simultaneous double fired

a fuel injection system that does not use a sensor to measure the amount (or mass) of air entering the engine is usually called a(n) _____ type of system

speed density

which fuel injection system uses the MAP sensor as the primary sensor to determine the base pulse width

speed density

what type of device is used in a typical idle air control

stepper Motor

all of the following are approved methods or tools used when diagnosing an ECT (engine coolant temperature) sensor EXCEPT

substituting a variable resistor

which term is used to describe a TBI system where the injector pulses once per distributor reference pulse

synchronized

tech a says that fuel filters aren located in the fuel supply line. tech b says that fuel filters are located in the fuel return line. which tech is correct

tech a

tech a says that a MAP sensor can be tested by visual inspection using a digital meter, or a scan tool. tech b says a light engine load results in low intake manifold vacuum and a high MAP sensor signal voltage

tech a only

tech a says that fuel tank accident and rollover protection devices include check values and inertia switches. tech b says that most fuel lines are made of ABS plastic.m who's right

tech a only

a _____ is a variable resistance sensor with 3 terminals

potentiometer

what type of sensor is used to measure the position of the throttle

potentiometer

What unit of electricity is used as a signal for a computer?

volt

GDI equipped engines have a higher efficiency due to a ____ compression ratio

higher

when checking the ECT sensor with a scan tool, about what temperature should be displayed if the connector is removed from the sensor with the key on, engine off

-40 degree f

the "brain" of the computer is the

CPU

most TP sensors have how many wires

3

when testing an ECT sensor on a vehicle, a digital multimeter can be used and the signal wires back probed. what setting should the technician use to test the sensor

DC volts

the sensor that most determines fuel delivery when a fuel injected engine is first started is the

ECT sensor

all OBDII vehicles use what type of read-only memory

EEPROM

the MAP sensor is used by the PCM to diagnose the _____ system

EGR

a TP sensor is what type of sensor

Potentiometer

which of these tools would be used to test a MAP sensor

a digital voltmeter

a typical MAP sensor compares the vacuum in the intake manifold to

a perfect vacuum

a GDI system operating in stratified mode results in

a rich air fuel mixture near the spark plug tip

which item is a computer input sensor

all of the above: engine coolant temperature, rpm, throttle position angle

which item is a computer output device

all of the above: fuel injector, evaporative emission control solenoid, transmission shift solenoid

the high pressure fuel pump pressure is regulated by using

an electric pressure control valve

most MAP sensors produce what type of output signal

analog DC volage (DCV)

analog signals from sensors are changed to digital signals for processing by the computer through which type of circuit

analog-to-digital converter

where is the fuel pressure regulator located on a vacuum biased port fuel injection system

at the outlet of the fuel rail

when the engine is at idle speed, manifold vacuum is

high (17 to 21 in. Hg)

tech a says that the ECT and IAT sensors can be tested visually, as well as by using a digital multimeter or a scan tool. tech b says that the ECT sensor is a high-authority sensor at engine start up and is used for open loop control, as well as idle speed. who is right

both techs

tech a says that the fuel pump relay is usually controlled by the PCM. tech b says that a TBI injector squirts fuel above the throttle plate. which tech is correct

both techs

tech a says that the purpose of the IAT sensor is to provide the engine computer (PCM) with the temperature of the air entering the engine. tech b says that the IAT sensor information is used for fuel control (adding or subtracting fuel) and spark timing, depending on the temperature of incoming air. who is right

both techs

tech a says that vehicles with electronic returnees fuel systems are pulse width modulation to power the fuel pump and maintain fuel pressure. tech b says that the electric returnees fuel system uses a power transistor to control the fuel pump. whose right

both techs

which term describes the PCM shutting off fuel injection when the accelerator all the way down

clear flood mode

computer speed is measured in

clock speed (Hz)

the TP sensor affects the operation of all of these, EXCEPT

correcting for rich and lean air fuel mixture

the amperage draw of an electric fuel pump is higher that specified. all of the following are possible causes EXECPT

corroded electrical connections at the pump motor

the amperage draw of an electric fuel pump is lower than specified. what is the most likely cause?

corroded electrical connections at the pump motor

all of the following are advantaged of gasoline direct injection EXCEPT

decreased throttle response

as the altitude of the vehicle increases, BARO voltage

decreases

an engine fuel temperature (EFT) sensor is used on some vehicles, since fuel temperature changes the ___ of the fuel

density

where is the fuel injected in an engine equipped with gasoline direct injections

directly into the combustion chamber

the ratio of on time relative to the period of the complete cycle is the

duty cycle

which of these sensors does that TP sensor back up if the PCM determines that a failure has occured

either b or c: MAP sensor and MAF sensor

a small amount of gasoline in the regulator vacuum hose is normal on older vehicles

false

where is the electric fuel pump is usually mounted

fuel tank

tech a says that other temperature sensors that operate like the ECT include transmission fluid temperature (TFT) and engine oil temperature sensors. tech b says that all temperature sensors increase in resistance as the temperature decreases. who is right

tech a only

tech a says that pressure below atmospheric pressure is called vacuum and is measured in inches of mercury (Hg). tech b says that a manifold absolute pressure (MAP) sensor uses a low vacuum in the sensor to determine the pressure. who's right

tech a only

tech a says that the 3 wires of the TP sensor include a 5 volt reference voltage from the PCM. tech b says that a TP sensor is a 3 wire variable resistor called a rheostat. who is right

tech a only

tech a says that vacuum operated fuel pressure regulators maintain an equal drop across the fuel injectors all the time. tech b says that intake manifold pressure is high at idle. who's right

tech a only

two techs are discussing MAP sensors. tech a says that the MAP sensor should be replaced if anything comes out of the sensor when the vacuum hose is removed from the sensor. tech b says that the injector pulse width should increase when vacuum to the MAP sensor is increased. who's right

tech a only

tech a says that the TP sensor signal voltage should be about 0.5 volts at idle and increases to about 2.5 volts at wide open throttle (WOT). tech b says a TP sensor can be tested using DMM or a scan tool. who's right

tech b

a MAP sensor is being discussed. tech a says that many MAP sensors act as a barometric pressure sensor when the ignition switch is turned off. tech b says that on many MAP sensors the signal voltage should increase when the vacuum at the sensor decreases. who's right

tech b only

tech a says that a heavy engine load results in high intake manifold vacuum and a high MAP sensor signal voltage. tech b says that a manifold absolute pressure (MAP) sensor uses a perfect vacuum (zero absolute pressure) in the sensor to determine the pressure. who's right

tech b only

tech a says that the 3 wires on the TP sensor include a 5 volt reference voltage from PCM plus the signal wire to PCM and a ground to the engine block. tech b says that the TP sensor is used by the PCM to determine torque converter engagement and transmission shift points. who's right

tech b only

two techs are discussing the IAT sensor. tech a says that the IAT sensor is more important to the operation of the engine (higher authority) than the ECT sensor. tech b says that the PCM adds fuel if the IAT indicated that the incoming air temperature is cold. who's right

tech b only

after a TP sensor has been tested using the min/max function on a DMM, a reading of zero volts is displayed. what does this reading indicate

the TP sensor is open at one point during the test

why is a vacuum line attached to a fuel pressure regulator on many port fuel engines

to create an equal pressure drop across the injectors

what two things can a vehicle computer actually perform (output)

turn something on or turn something off

a scan tool can be used to test a MAP sensor by monitoring the injector pulse width (in milliseconds) while _____ nis being applied to the MAP sensor

vacuum