Engine Performance
Which emission control device is used to reduce combustion chamber temperatures? -PCV -EVAP -EGR - None of the above
-EGR
The EVAP system is used to limit which emission? -CO2 -HC -CO -O2
-HC
What voltage reading would you expect to find on pin 4 of the fuel pump 12v a) __ 0-5.5v b) __ 4.5-5.5v c) __ 0v d)__
0-5.5v b) __
Which of the following is the most likely cause of a lean condition during acceleration and cruising speeds? a. A defective oxygen sensor b. A defective PCM c. A defective ECT sensor d. A defective MAF sensor
A defective MAF sensor
The ignition module has direct control over the firing of the coil(s) of an EI system. Which component(s) triggers (controls) the module? Pickup coil Computer Crankshaft sensor All of the above
All of the above
A vehicle has zero fuel pressure. Technician A says the inertia switch may be open. Technician B says the inertia switch may be shorted. Who is correct?
Both A and B
Technician A says a restricted fuel injector can cause a lean condition. Technician B says an injector balance test may locate a restricted injector. Who is correct?
Both A and B
Technician A says to relieve fuel system pressure before opening a fuel line. Technician B says to use only the proper tools for disconnecting fuel lines. Who is correct?
Both A and B
Technician A says that spark knock, ping, and detonation are different names for abnormal combustion. Technician B says that any abnormal combustion raises the temperature and pressure inside the combustion chamber and can cause severe engine damage. Which technician is correct? Technician A Technician B Both Technicians Neither Technician
Both Technicians
Two technicians are discussing a no-start (no-spark) condition. Technician A says that an open CKP sensor could be the cause. Technician B says that a defective ignition control module (ICM) could be the cause. Which technician is correct? Technician A Technician B Both Technician Neither Technician
Both Technicians
What are two exhaust system problems that can affect engine performance?
Exhaust Leaks Catalytic Converter Blockage
Which exhaust emission is an indicator that ideal combustion is taking place?
Low carbon monoxide (CO) emissions are an indicator that ideal combustion is taking place.
How can variable intake runners increase performance?
Optimizes the length and diameter of the intake runners based on engine speed and load.
Which one of these sensors is NOT used to determine injector pulse width during open-loop mode? ECT sensor TP sensor MAF sensor Oxygen sensor
Oxygen sensor
Describe two methods of testing the EVAP system.
Pressure Testing/Leak down Testing Smoke Testing
How does oxygen sensor data affect fuel trim?
Provides feedback on the air-fuel mixture's actual composition in the exhaust gases.
What are two ways to reduce turbo lag?
Reduce Turbo Size Variable Geometry Turbochargers
What part of the scope pattern shows the duration of the spark? Firing line Spark line Intermediate section Dwell section
Spark Line
Technician A says a vacuum leak can make an engine run lean. Technician B says a vacuum leak has no effect on an MAF-equipped engine. Who is correct?
Technician A
wo Technicians are discussing the fuel system. Technician A says pin one of the injectors is ground. Technician B says the fuel level sensor goes to the instrument cluster. Which Technician is correct? Technician A a) __ Technician B b) __ Both Technicians c) __ Neither Technician d)
Technician A a) __
A compression-sensing ignition is what type? Distributor Waste spark Coil-on-plug Any of the above
Waste Spark
At which time would you expect to find power on pin 6 of fuel pump all the time? With key in the on position a) __ With the key in the off position b) __ With the key in the start position c) __ All of the time
With key in the on position a) __
Which of the following statements about EVAP systems is not true? a. If the system is purging vapors from the charcoal canister when the engine is running at high speeds, rough engine operation will occur. b. Cracked hoses or a canister saturated with gasoline may allow gasoline vapors to escape to the atmosphere, resulting in gasoline odor in and around the vehicle. c. Rough idle, flooding, and other similar conditions can indicate a saturated canister. d. A vacuum leak in the system can cause
a. If the system is purging vapors from the charcoal canister when the engine is running at high speeds, rough engine operation will occur.
What happens to the voltage measured at the ECT sensor when the thermostat opens? a. Increases slightly b. Increases about 1 volt c. Decreases slightly d. Decreases about 1 volt
a. Increases slightly
Which of the following statements concerning superchargers is incorrect? a. Superchargers must overcome inertia and spin up to speed as the flow of exhaust gas increases. b. Superchargers do not require a wastegate to limit boost. c. A bypass is designed into the system to allow the supercharger to idle along when extra power is not needed. d. Superchargers improve horsepower and torque.
a. Superchargers must overcome inertia and spin up to speed as the flow of exhaust gas increases.
A vehicle is setting a lean exhaust code and the HO2S data shows the exhaust to be very lean. Technician A says a malfunctioning AIR system may be the cause. Technician B says a clogged EGR may be the cause. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
Technician A says that air-fuel ratios can be regulated by controlling the "on time" of the injectors. Technician B says that the air-fuel ratio can be regulated by controlling the pressure applied to the individual injectors. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
Technician A says vacuum is pressure less than atmospheric pressure. Technician B says vacuum starts at zero atmospheric pressure. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
While discussing GDI systems: Technician A says that this type of system allows engines to run at very lean air-fuel ratios and at higher-than-normal compression ratios. Technician B says that GDI systems eliminate the need to have an EGR valve on the engine. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
While discussing PCV systems without a PCV valve: Technician A says that blowby gases are routed into the intake manifold through a fixed orifice tube. The system works the same as if it had a valve, except that the system is regulated only by the vacuum at the orifice and the size of the orifice. Technician B says that VVT systems eliminate the need for a PCV system. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
While discussing SFI systems: Technician A says that when the injection system fires according to crankshaft position and speed, it is operating in the synchronous mode. Technician B says that one of the advantages of SFI systems is that they are always in the synchronous mode. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
While discussing air-fuel ratios: Technician A says that a stoichiometric mixture is theoretically the best combination of fuel and air to provide for total combustion. Technician B says that a stoichiometric mixture always results in complete combustion. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
While discussing airflow sensors: Technician A says that with mass airflow and volume airflow sensor systems, if any air bypasses the sensors, the engine will run lean. Technician B says that vacuum leaks in a speed density system will decrease injector pulse width. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
While discussing catalytic converter diagnosis: Technician A says that Mode $06 data should be checked. Technician B says that a good converter is evident by low amounts of CO2 in the exhaust. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
While discussing central port injection systems: Technician A says that CPI systems use one injector and several injector nozzles. Technician B says that CPI systems open each injector sequentially. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
While discussing tailpipe emissions and cylinder misfiring: Technician A says that cylinder misfiring causes a significant increase in HC emissions. Technician B says that cylinder misfiring results in a large in-crease in CO emissions. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
Technician A says that the exhaust manifold gasket seals the joint between the exhaust manifold and the exhaust pipe. Technician B says that a resonator helps to reduce exhaust noise. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician B
What manages turbo output by controlling the amount of exhaust gas entering the turbine housing? a. Wastegate b. Turbine seal assembly c. Turbine d. Compressor
a. Wastegate
The customer states the engine hesitates during acceleration, lacks power, and seems to surge sometimes. The Technician has found no DTC's and the visual inspection comes back good. The scan tool data shows the airflow to be .5 grams per second. What should the technician inspect next? a. __A blocked MAF b. __A failed MAF control c. __For a shorted MAF d. __Intake leak
a. __A blocked MAF
The Technician has hooked up the scan tool and found code P0171. The technician has verified the issue is not fuel related. The TPS and MAF are ok. What should the technician check for next? a. __A leak in the intake b. __A leaking injector c. __A broken exhaust valve d. __A clogged air filter
a. __A leak in the intake
The amperage draw of an electric fuel pump is higher than specified. All of the following are possible causes Except __________ a. clogged fuel filter b. restriction in the fuel line c. corroded electrical connections at the pump motor d. defective fuel pump
a. clogged fuel filter
Poor engine performance could be the result of a__________. defective coil distributor ignition with the CMP and CKP not correctly indexed a high-voltage spark leak any of the above
any of the above
Typical TP sensor voltage at idle is about ________. a. 2.50 to 2.80 volts b. 0.5 volt or 10% of WOT TP sensor voltage c. 1.5 to 2.8 volts d. 13.5 to 15.0 volts
b. 0.5 volt or 10% of WOT TP sensor voltage
A typical IAT or ECT sensor reads about 3,000 ohms when tested using a DMM. This resistance represents a temperature of about ________. a. -40°F b. 70°F (20°C) c. 120°F (50°C) d. 284°F (140°C)
b. 70°F (20°C)
The PCM checks for a closed throttle plate each time the engine starts. This becomes the base for all throttle settings and can be viewed by looking at the PID with the throttle closed. Which of the following would not cause an abnormal reading and a higher-than-normal idle speed? a. A bad TP sensor b. A bad IAC valve c. Loose or worn throttle plates d. Excessive noise in the TP or related circuits
b. A bad IAC valve
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? a. AC volts b. DC volts c. Ohms d. Hz (Hertz)
b. DC volts
Which of the following systems is designed to reduce NOx and has little or no effect on overall engine performance? a. PCV b. EGR c. AIR d. EVAP
b. EGR
Which of the following is not characteristic of a supercharger? a. It is used to increase engine power by compressing the air that goes into the combustion chambers. b. It usually is located close to the exhaust manifold. c. It utilizes a belt-driven pulley. d. It requires a mechanical connection between the engine and the pressurizing pump to compress the intake gases.
b. It usually is located close to the exhaust manifold.
Which of the following exhaust gases is typically not measured during an I/M 240 test? a. HC b. O2 c. NOx d. CO
b. O2
To isolate the high voltage system on most hybrids, what should be done? a. Disconnect the 12V cables b. Remove, disconnect, or turn the service plug to "off" c. Make sure the ignition is off d. Keep the smart key in your pocket
b. Remove, disconnect, or turn the service plug to "off"
Technician A says inspection mode is used to bypass the HV system. Technician B says inspection mode is used to shut off the ICE. Which Technician is correct? a. Technician A b. Technician B c. Both Technicians d. Neither Technician
b. Technician B
Technician A says that a turbocharger has its own self-contained lubrication system. Technician B says that a turbocharger should not be operated when the engine's oil pressure is lower than 30 psi. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
Technician A says that a vacuum leak results in less air entering the engine, which causes a richer air-fuel mixture. Technician B says that a vacuum leak can cause the engine to run poorly. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
Technician A says that an overfilled Prius will cause a no start. Technician B says a Prius with an empty tank will not start. Which Technician is correct? a. Technician A b. Technician B c. Both Technicians d. Neither Technician
b. Technician B
Technician A says that the catalytic converter is used only to quiet the noise of the exhaust. Technician B says that the catalytic converter is used to alter the contents of the engine's exhaust. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
Technician A says that vacuum hose routing for the entire vehicle is illustrated on the underhood decal. Technician B says that this decal illustrates emission system vacuum hose routing. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
Technician A says vacuum refers to any pressure that is greater than atmospheric pressure. Technician B says vacuum changes based on altitude. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
When discussing the diagnosis of a positive back pressure EGR valve: Technician A says that with the engine running at idle speed, if a hand pump is used to supply vacuum to the EGR valve, the valve should open at 12 in. Hg of vacuum. Technician B says that with the engine not running, any vacuum supplied to the EGR valve should be bled off and the valve's diaphragm should not move. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While diagnosing a PCV problem: Technician A says that a stuck open PCV valve will cause a richer than normal air-fuel mixture. Technician B says that oil in the air cleaner assembly can be caused by a restricted PCV hose. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While discussing EGR systems with a differential pressure feedback electronic (DPFE) sensor: Technician A says that the DPFE sensor sends a signal to the PCM in relation to intake manifold pressure. Technician B says that the PCM corrects the EGR flow if the actual flow does not match the requested flow. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While discussing EGR valve diagnosis: Technician A says that if the EGR valve does not open, the engine may hesitate on acceleration. Technician B says that if the EGR valve does not open, the engine may detonate on acceleration. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While discussing IAC motor removal, service, and replacement: Technician A says that throttle body cleaner may be used to clean the IAC motor internal components. Technician B says that on some vehicles, IAC motor damage occurs if the pintle is extended more than specified during installation. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While discussing SCR systems: Technician A says that they are used in place of a conventional catalytic converter to reduce NOx, CO, and HC. Technician B says that the most common reductant used is SCR systems is an ammonia-like substance called urea. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While discussing electronic fuel injection principles: Technician A says that the PCM always adjusts the air-fuel ratio in response to the O2S signals. Technician B says that STFT is based on the output of the O2S signals. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While discussing returnless fuel systems: Technician A says that in a returnless fuel system the pressure regulator is mounted on the fuel rail. Technician B says that in this type of fuel system the pump and pressure regulator are combined in one unit. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While discussing the causes of higher-than-specified fuel pressure: Technician A says that a leaking fuel pressure regulator on a PFI system may cause high fuel pressure. Technician B says that if the fuel return line is restricted, fuel pressure may be higher than normal. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While discussing the compression ratios used with engines equipped with a GDI system: Technician A says that higher ratios can be used because ignition timing is normally very advanced. Technician B says that higher ratios are possible because the small droplets of fuel injected directly into the cylinder tend to cool the mixture in the cylinder. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While looking at fuel trim values: Technician A says that restricted or dirty injectors may be evident by a negative LTFT. Technician B says that a faulty fuel pressure regulator may result in a negative LTFT. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
A P0118 DTC is being discussed. Technician A says that the ECT sensor could be shorted internally. Technician B says that the signal wire could be open. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B
b. Technician B only
Two technicians are discussing the IAT sensor. Technician A says that the IAT sensor is more important to the operation of the engine (higher authority) than the ECT sensor. Technician B says that the PCM will add fuel if the IAT indicates that the incoming air temperature is cold. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians d. Neither Technician
b. Technician B only
The hybrid vehicle "ready" light is on. The ICE is not running, what may happen? a. The ICE may start due to the low 12-volt battery voltage b. The ICE may start due to the low high voltage battery voltage c. Both A and C d. Neither A or B
b. The ICE may start due to the low high voltage battery voltage
The Technician has swapped the coil and spark plug. The misfire stayed in cylinder 4. What is the next step? a. __Check for spark in cylinder 4 b. __Check the injector c. __Pull up wiring diagram and find next test point d. __Pull up diagnostic walk through
b. __Check the injector
A technician is diagnosing a TPS. With the scan tool hooked up, KOEO the TP sensor reads 4.5 volts. Technician A says this is a normally operating system. Technician B says this indicates the throttle is stuck open, or the TPS or circuit has a failure. Which Technician is correct? a. __Technician A b. __Technician B c. __Both Technicians d. __Neither Technician
b. __Technician B
A technician is diagnosing a customer concern that the engine is running rough. When the vehicle is put in reverse it seems to run fine. Technician A says to inspect the motor mounts. Technician B says there is likely an intake leak at the air box and further inspection is required. Which Technician is correct? a. __Technician A b. __Technician B c. __Both Technicians d. __Neither Technician
b. __Technician B
The Technician has hooked up an oscilloscope on the crankshaft and camshaft position sensors (2016 Altima). Technician A says this is a normal reading and that further testing must be done. Technician B says that the camshaft position sensor on bank 1 needs further testing. Which Technician is correct? a. __Technician A b. __Technician B c. __Both Technician A and B d. __Neither Technician
b. __Technician B
The Technician is diagnosing a customer concern that the fuel gauge is not working. The Technician tests B42 pin 5 to M24 pin 27 and finds no continuity. Technician A says this is normal and to continue to the next step. Technician B says that this is not normal and the harness needs to be repaired/replaced. Which Technician is correct? a. __Technician A b. __Technician B c. __Both Technicians d. __Neither Technician
b. __Technician B
Two Technicians are discussing pinpointing an air leak. Technician A says that if you spray brake clean, and it enters the intake, the RPM will drop. Technician B says that you can hook up a smoke tester to the system to identify the location of the intake leak. Which Technician is correct? a. __Technician A b. __Technician B c. __Both Technicians d. __Neither Technician
b. __Technician B
Which of the following would not cause a hard-to-start problem on a PFI engine? a. A defective IAC valve b. A defective oxygen sensor c. A leaking fuel pressure regulator d. Dirty injectors
b. defective oxygen sensor
As a catalytic converter begins to deteriorate, the signal from the postcatalyst HO2S becomes ___ the signal of the precatalyst HO2S. a. shorter than b. more like c. larger than d. flatter than
b. more like
If a fuel system loses pressure immediately after the ignition is turned off, the possible problems are all of the following except ___. a. a leaking injector b. restricted fuel lines c. leaking connectors or hoses d. a faulty pressure regulator
b. restricted fuel lines
Most fuel tank filler caps contain a pressure valve and a ___. a. vapor separator b. vacuum relief valve c. one-way check valve d. surge plate
b. vacuum relief valve
What charging current rate is recommended for a 12V hybrid battery? a. 2.5 AMPS b. 3.5 AMPS c. 4.5 AMPS d. 5.5 AMPS
c. 4.5 AMPS
Orange wires on a hybrid vehicle indicate the voltage is at least: a. 12 volts b. 36 volts c. 60 volts d. None of the above
c. 60 volts
When testing an EGR system with a scan tool, the EGR is commanded open but the engine speed does not change. Technician A says the EGR may be faulty. Technician B says the EGR passages may be plugged. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and
A vehicle's intake manifold is warped: Technician A says the manifold may need to be replaced. Technician B says the manifold may be able to be filed flat and reused. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
Before replacing any exhaust system component: Technician A soaks all old connections with penetrating oil. Technician B checks the old system's routing for critical clearance points. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
Technician A makes sure that the exhaust system is cool to the touch before working on it. Technician B disconnects the battery's negative cable before welding an exhaust pipe. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
Technician A says rich exhaust will have a high HC reading. Technician B says a rich exhaust will have a high CO reading. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
Technician A says that an EGR valve that is stuck open can cause idle problems. Technician B says that a stuck closed EGR can increase HC emissions. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
Technician A says that the AIR system should pump air into the exhaust manifold(s) during engine warmup. Technician B says that the secondary air system check valve can be checked with an exhaust gas analyzer. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
Which of the following is necessary to have in a shop while working on a hybrid vehicle? a. Lineman's 1000 volt class"0" gloves b. CATIII DMM c. Both A and B d. Neither
c. Both A and B
While diagnosing an idle speed problem: Technician A says that higher-than-normal TP signals at idle will cause the IAC to close, which will decrease idle speed. Technician B says that if the resistance of the ECT is too low, a lower-than-normal voltage signal is sent to the PCM, which interprets this as a hot engine and will close the IAC to decrease speed. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While diagnosing the cause of high HC and O2 emissions: Technician A says that the HC may be elevated because of an ignition problem. Technician B says that the O2 may be elevated because of an ignition problem. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing EGR valve diagnosis: Technician A says that a defective throttle position sensor may affect the EGR valve operation. Technician B says that a defective engine coolant temperature (ECT) sensor may affect the EGR valve operation. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing EVAP testing: Technician A says that most OEMs recommend that clean, high-pressure shop air be used to pressurize the system to test for leaks. Technician B says that nitrogen is typically used to drive the smoke through the system when checking the system with a smoke machine. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing IAC valve diagnosis: Technician A says that on some vehicles, a jumper wire may be connected to specific DLC terminals to check the IAC valve operation. Technician B says that if the scan tester indicates zero IAC valve counts, there may be an open circuit between the PCM and the IAC valve. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing PCV system diagnosis: Technician A says that a defective PCV valve may cause rough idle operation. Technician B says that satisfactory PCV system operation depends on a properly sealed engine. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing a high idle speed problem: Technician A says that higher-than-normal idle speed may be caused by low electrical system voltage. Technician B says that higher-than-normal idle speed may be caused by a defective coolant temperature sensor. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing automotive emissions: Technician A says that oxygen emissions are monitored because they are an indication of the completeness of the combustion process. Technician B says that the conditions for minimizing HC emissions are the same as those that cause high NOx emissions. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing electric exhaust gas recirculation (EEGR) systems: Technician A says that some are air cooled. Technician B says that some are cooled by engine coolant. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing evaporative (EVAP) systems: Technician A says that the coolant temperature has to be above a preset value before the PCM will operate the canister purge solenoid. Technician B says that the vehicle speed has to be above a preset value before the PCM will operate the canister purge solenoid. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing injector testing: Technician A says that a defective injector may cause cylinder misfiring at idle speed. Technician B says that restricted injector tips may result in acceleration stumbles. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing scan tool diagnosis of fuel injection systems: Technician A says that the scan tool may allow for control over some systems and components on many systems. Technician B says that many scan tools will store sensor readings during a road test and then play back the results in a snapshot test mode. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing the causes of a rich air-fuel ratio: Technician A says that a rich air-fuel ratio may be caused by a faulty fuel rail pressure sensor. Technician B says that a rich air-fuel ratio may be caused by a defective coolant temperature sensor. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing the comprehensive monitoring system: Technician A says that it tests various input circuits. Technician B says that it tests various output circuits. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing the proper way to test a catalytic converter: Technician A says that a pressure gauge can be inserted into the oxygen sensor bore and the backpressure caused by the converter measured. Technician B says that restrictions in the converter can be checked with a vacuum gauge while the engine is being quickly accelerated. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing throttle-by-wire systems: Technician A says that a spring on the throttle shaft provides the limp-home feature. Technician B says that most systems have redundant processors and the TP and accelerator pedal sensors send redundant input signals. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
Technician A says all hybrid vehicles have an inspection mode. Technician B says most hybrid vehicles have an inspection mode. Which Technician is correct? a. Technician A b. Technician B c. Both Technicians d. Neither Technician
c. Both Technicians
Which sensor is used for misfire monitoring on OBD II systems? a. Oxygen sensor b. Camshaft position sensor c. Crankshaft position sensor d. DPFE sensor
c. Crankshaft position sensor
When testing the ECT sensor with the connector disconnected, the technician should select what position on the DMM? a. AC volts b. DC volts c. Ohms d. Hz (Hertz)
c. Ohms
What is the first step in turbocharger inspection? a. Check the air cleaner for a dirty element. b. Open the turbine housing at both ends. c. Start the engine and listen to the system. d. Remove the ducting from the air cleaner to the turbo and examine the area.
c. Start the engine and listen to the system.
While diagnosing a vehicle with a no start condition, the technician hooks up the oscilloscope to the injector using amperes. The waveform is flat lines. What is the next step in diagnosing the issue? a. __Test injector resistance b. __Check the power to the injector c. __Check the fuse/relay d. __Test the battery
c. __Check the fuse/relay
The Technician is testing the fuel pump relay control. The Technician is testing from F14 pin 18- E10 pin 128. What test is the Technician performing? a. __Continuity b. __Amperes c. __Voltage drop d. __Available voltage
c. __Voltage drop
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? a. 284°F (140°C) b. 230°F (110°C) c. 120°F (50°C) d. -40°F (-40°C)
d. -40°F (-40°C)
How much pressure does a typical EVAP pressure tester apply to the system during testing? a. 14 in. Hg b. 14 psi c. 1 in. H2O d. 0.5 psi
d. 0.5 psi
Ten psi of turbo boost means that air is being fed into the engine at ___ when the engine is operating at sea level. a. 4.7 psia b. 10 psia c. 14.7 psia d. 24.7 psia
d. 24.7 psia
Before towing a hybrid, what precautions should you take? a. Make sure the system is off b. Chock the wheels c. Use the proper tow truck d. All of the above
d. All of the above
Isolating the high voltage battery from the system means? a. Turning off the ignition switch b. Turning off the HV switch c. Removing/disconnecting the HV safety plug d. All of the above
d. All of the above
The sensor that most determines fuel delivery when a fuel‑injected engine is first started is the ________. a. O2S b. ECT sensor c. engine MAP sensor d. IAT sensor
d. IAT sensor
Technician A says that during oxidation, as NOx gases pass over the catalyst, the N atoms are pulled from the NOx molecules and are absorbed by the catalyst. The released oxygen atoms then flow through the converter to the second bed. The result of NOx oxidation is pure nitrogen plus oxygen or carbon dioxide. Technician B says that during the reduction phase inside the converter, hydrocarbon and carbon monoxide molecules experience a second combustion. The result of this combustion or oxidation
d. Neither A nor B
Technician A says the catalytic converter only controls HC emissions. Technician B says the catalytic converter produces large amounts of CO2 during operation. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
d. Neither A nor B
Technician A uses sandpaper to remove carbon deposits from turbocharger wastegate parts. Technician B scrapes off heavy deposits before attempting to clean the unit. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
d. Neither A nor B
While discussing PCV valve operation: Technician A says that the PCV valve opening is decreased at part-throttle operation compared to idle operation. Technician B says that the PCV valve opening is decreased at wide-open throttle compared to part throttle. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
d. Neither A nor B
Which of the following statements about carbon dioxide is not true? a. CO2 levels are highest when the air-fuel ratio is slightly leaner than stoichiometric. b. The production of CO2 is directly related to the amount of fuel consumed; therefore, more fuel-efficient engines produce less CO2. c. To reduce CO2 levels in the exhaust, engineers are working hard to decrease fuel consumption to keep CO2 low. d. The concern for CO2 emissions is one of the primary reasons for the delayed use of alternati
d. The concern for CO2 emissions is one of the primary reasons for the delayed use of alternative fuels for automobiles.
The technician has verified the customer concern: engine is running rough. The Technician has hooked up the scan tool and found the above data for the cylinders. Based on these findings, what is the next step? a. __Check the maintenance history b. __Swap cylinder 4 coil to cylinder 2 and cylinder 4 spark plug to cylinder 3 c. __Verify spark on cylinder 4 d. __Check for available voltage at coil
d. __Check for available voltage at coil
A restricted exhaust system can cause ___. a. stalling b. loss of power c. backfiring d. all of the above
d. all of the above
An EGR valve that does not fully close can cause all of the following except ___. a. a no-start b. stalling c. surging d. detonation
d. detonation
The catalyst monitor test may fail for all of these reasons, except ___. a. defective upstream or downstream oxygen sensor circuits b. a leaking exhaust c. fuel contaminants d. ignition system misfire
d. ignition system misfire
A restricted catalytic converter can cause all of the following except ___. a. stalling after the engine starts b. popping or backfiring through the intake manifold c. a drop in engine vacuum d. increased power at high speeds
d. increased power at high speeds
A mini-converter is used ___. a. on small vehicles where a normal converter will not fit properly b. on engines that use leaded fuels c. in conjunction with EGR systems to supply clean exhaust for the cylinders d. to reduce emissions during engine warmup
d. to reduce emissions during engine warmup
The high-pressure fuel pumps used in gasoline direct injection (GDI) systems are powered by ______. electricity (DC motor) electricity (AC motor) the camshaft the crankshaft
electricity (DC motor)
The gasoline burned inside the internal combustion engine is a type of___________ carbon monoxide hydrocarbon compressed vapor alcohol
hydrocarbon
Avoid topping off the fuel tank because _______________________. it can saturate the charcoal canister the extra fuel simply spills onto the ground the extra fuel increases vehicle weight and reduces performance the extra fuel goes into the expansion area of the tank and is not used by the engine
it can saturate the charcoal canister
A reluctor is a_________________ type of sensor used in the secondary circuit notched ring or pointed wheel type of optical sensor type of Hall-effect sensor
notched ring or pointed wheel
A good fuel pump should be able to supply how much fuel per minute? ¼ pint ½ pint 1 pint 0.5 to 0.8 gallons
0.5 to 0.8 gallons
The fuel injectors used on a gasoline direct-injection system are pulsed on using what voltage? 12 to 14 50 to 90 100 to 110 200 to 220
50 to 90
The fuel injectors operate under a fuel pressure of about ________. 35 to 45 psi 90 to 150 psi 500 to 2,900 psi 2,000 to 5,000 psi
500 to 2,900 psi
A vehicle with a 4-cylinder engine has an illuminated MIL and a rough idle A "fuel system too lean-Bank I" DTC is found stored. With the engine idling, the short-term fuel term (STFT) is +18% and the long-term fuel term (LTFT) is +25%. When power braking is closed-loop, the technician observes both STFT and LTFT drop into the normal range. Which of these could be the cause? A. A ruptured PCV valve diaphragm B. Low fuel flow from the fuel pump C. A shown rich B151 oxygen sensor D. A contaminated Mass airflow sensor
A. A ruptured PCV valve diaphragm
How does A/F ratio sensor operation differ from traditional HO2S operation?
A/F ratio sensor (Air-Fuel Ratio Sensor) is more precise and measures the air-fuel mixture's exact ratio providing more accurate feedback to the engine control module for better fuel control HO2S (Heated Oxygen Sensor) monitors whether the mixture is rich or lean. Indicating whether the mixture needs adjustment.
Technician A says GDI systems use high-pressure mechanical pumps to deliver fuel to injectors. Technician B says GDI systems also use PFI injectors. Who is correct?
Both A and B
Technician A says that the fuel pump relay is usually controlled by the PCM. Technician B says that a TBI injector squirts fuel above the throttle above the throttle plate. Which technician is correct? Technician A Technician B Both Technicians Neither Technician
Both Technicians
While discussing electric fuel pumps: Technician A says that some electric fuel pumps are combined in one unit with the gauge sending unit. Technician B says that on an engine with an electric fuel pump, low engine oil pressure may cause the engine to stop running. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
C. Both A and B
Which OBD II monitor is responsible for verifying proper engine operating temperature?
Catalyst Monitor
What is the difference between a DTC and a PID?
DTC is a specific code that identifies if something is wrong with the vehicle PID (Parameter Identification) shows real-time data about how your car is running, but it doesn't indicate a problem by itself.
Where is the fuel injected in an engine equipped with gasoline direct injection? Into the intake manifold near the intake valve Directly into the combustion chamber Above the intake port In the exhaust port
Directly into the combustion chamber
What can be used to measure the alcohol content in gasoline? Graduated cylinder Electronic tester Scan tool Either Graduated cylinder or tester
Either Graduated cylinder or tester
If it is tripped, which type of safety device will keep the electric fuel pump from operating? Roll-over valve Inertia switch Anti-siphoning valve Check valve
Inertia switch
Where is the fuel pump located on most vehicles today? Near the fuel injectors under the hood Attached to the outside of the fuel tank Inside the fuel tank Mounted on the engine
Inside the fuel tank
Describe why so many inputs are used to control the fuel injection system.
It enables the system to respond effectively to varying driving conditions and maintain engine operation within desired parameters.
What are the two basic methods used for measuring the amount of air the engine is breathing in, in order to match the correct fuel delivery?
Mass Airflow Sensor (MAF) & Manifold Absolute Pressure (MAP) Sensor
What prevents the fuel pump inside the fuel tank from catching the gasoline on fire? Electricity is not used to power the pump No air is around the motor brushes Gasoline is hard to ignite in a closed space All of the above
No air is around the motor brushes
How many reading DTCs differ on OBD I vehicles compared to OBD II vehicles?
OBD I vehicles typically have one or two "Reading DTCs" OBD II vehicles have a more comprehensive range of modes.
Technician A says positive fuel trim means the PCM is adding fuel beyond the base calculation. Technician B says excessive positive fuel trim indicates a lean exhaust condition. Who is correct?
Technician B
Technician A says Mode 6 data is used to identify stored DTCs. Technician B says Mode 6 data can be used to identify possible pending concerns. Who is correct?
Technician B is correct.
Technician A says an air-fuel ratio of 12:1 is a lean mixture. Technician B says an air-fuel ratio of 12:1 is a rich mixture. Who is correct?
Technician B is correct.
Explain what stoichiometric means
The ideal air-fuel mixture in an internal combustion engine, where there is precisely enough air to completely burn the fuel, resulting in efficient and balanced combustion.
Why is a vacuum line attached to a fuel-pressure regulator on many port-fuel-injected engines? To draw fuel back into the intake manifold through the vacuum hose To create an equal pressure drop across the injectors To raise the fuel pressure at idle To lower the fuel pressure under heavy engine load conditions to help improve fuel economy
To create an equal pressure drop across the injectors
Why must the spark timing begin earlier as engine speed increases?
To ensure that the air-fuel mixture ignites at the right moment in the engine's four-stroke cycle.
What are three ways in which OBD II has standardized onboard computer systems?
Universal Diagnostic Trouble Codes (DTCs) Universal Data Link Connector (DLC) Common Communication Protocols
Which of the following statements about fuel trim is not true? a. A positive fuel trim value means that the PCM detects a lean mixture and is decreasing the pulse width to add more fuel to the mixture. b. Short-term fuel trim represents changes made immediately in response to HO2S signals. c. Long-term fuel trim represents changes made to set a new base pulse width. d. Long-term fuel trim responds to the trends of the short-term fuel trim.
a. A positive fuel trim value means that the PCM detects a lean mixture and is decreasing the pulse width to add more fuel to the mixture.
The amperage draw of an electric fuel pump is lower than specified. What is the most likely cause? a. Corroded electrical connections at the pump motor b. Clogged fuel filter c. Restriction in the fuel line d. Stuck fuel pump impeller blades
a. Corroded electrical connections at the pump motor
What component pulses the fuel injector on most vehicles? a. Powertrain control module (PCM) b. Ignition module c. Crankshaft sensor d. Both b and c
a. Powertrain control module (PCM)
Technician A says an exhaust leak before the 02 sensor can cause incorrect sensor readings. Technician B says both pre- and post-catalyst O2 sensors should cycle rapidly between rich and lean. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
Technician A says switches can be checked with an ohmmeter or voltmeter. Technician B says temperature sensors can be checked with an ohmmeter. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
Technician A says that a faulty MAF sensor can cause the engine to run lean. Technician B says that a faulty MAP sensor can cause the engine to not start. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
Technician A says that an oxygen sensor can be a voltage-producing sensor. Technician B says that an oxygen sensor is a thermistor sensor. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
Technician A says that the enable criteria are the criteria that must be met before the PCM completes a monitor test. Technician B says that a drive cycle includes operating the vehicle under specific conditions so that a monitor test can be completed. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
While discussing PCM monitor tests: Technician A says that some monitors only run after another monitor completes. Technician B says that the monitor tests are run when the scan tool activates them. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
While discussing electric fuel pumps: Technician A says that some electric fuel pumps in EFI systems are computer controlled. Technician B says that fuel pump pressure is determined by measuring the amount of fuel that the pump will deliver in a specific length of time. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
While discussing electric fuel pumps: Technician A says that the one-way check valve prevents fuel flow from the underhood fuel system components into the fuel pump and tank when the engine is shut off. Technician B says that the one-way check valve prevents fuel flow from the pump to the fuel filter and fuel system if the engine stalls and the ignition switch is on. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
While discussing fuel filters: Technician A says that on some vehicles the fuel filter is not serviceable as a regular maintenance item. Technician B says that some fuel filters are located in the fuel return lines. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
While discussing fuel tank filler pipes and caps: Technician A says that the threaded filler cap should be tightened until it clicks. Technician B says that the vent pipe is connected from the top of the filler pipe to the bottom of the fuel tank. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
While discussing the MIL on OBD II systems: Technician A says that the MIL will flash if the PCM detects a fault that would damage the catalytic converter. Technician B says that whenever the PCM has detected a fault, it will turn on the MIL. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
a. Technician A
Two technicians are diagnosing a poorly running engine. There are no diagnostic trouble codes. When the MAF sensor is unplugged, the engine runs better. Technician A says that this means that the MAF is supplying incorrect air flow information to the PCM. Technician B says that this indicates that the PCM is defective. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B
a. Technician A only
The typical MAF reading on a scan tool with the engine at idle speed and normal operating temperature is _____. a. 1 to 3 grams per second b. 3 to 7 grams per second c. 8 to 12 grams per second d. 14 to 24 grams per second
b. 3 to 7 grams per second
Which of the following is the least likely cause of a no-start condition? a. Faulty CKP sensor b. Faulty KS c. Fuel or ignition system faults d. Faulty PCM wiring
b. Faulty KS
Which of the following statements about zirconium oxygen sensors is not true? a. The normal operating range for an O2S is between 0 and 1 volt. b. If the sensor's voltage toggles between 0 volts and 500 millivolts, it is operating normally. c. The voltage signal from an upstream O2S should have seven cross counts within 5 seconds with the engine running without a load at 2,500 rpm. d. Engine control systems monitor the activity of the O2S and store a code when the sensor's output is not within the desired range.
b. If the sensor's voltage toggles between 0 volts and 500 millivolts, it is operating normally.
Which type of fuel injection system has the fuel pressure regulator located in the fuel tank? a. Throttle body injection b. Mechanical returnless PFI c. Electronic returnless PFI d. Central multipoint injection
b. Mechanical returnless PFI
If the MAF sensor fails, the PCM uses ________ to calculate fuel delivery needs. a. MAP and throttle position b. RPM and throttle position c. throttle position and transmission RPM d. RPM alone
b. RPM and throttle position
Which wire on a TP sensor should be back-probed to check the voltage signal to the PCM? a. 5-volt reference b. Signal c. Ground d. Meter should be connected between the 5-volt reference and the ground
b. Signal
Technician A replaces a damaged steel fuel line with one made of synthetic rubber. Technician B replaces a damaged steel fuel line with one made of steel. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
Technician A says that fuel pump modules are spring-loaded so that they can be compressed to fit into the opening. Technician B says that they are spring-loaded to allow for expansion and contraction of plastic fuel tanks. Which technician is correct? a. Technician A b. Technician B c. Both Technicians d. Neither Technician
b. Technician B
While discussing EFI systems: Technician A says that the PCM provides the proper air-fuel ratio by controlling the fuel pressure. Technician B says that the PCM provides the proper air-fuel ratio by controlling injector pulse width. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While discussing Hall-effect vehicle speed sensor tests: Technician A says to use an ohmmeter to test the resistance of the coil. Technician B says that the voltage generated by the sensor can be measured by connecting a voltmeter across the sensor's terminals. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While discussing diagnostic procedures: Technician A says that after the visual inspection has been per-formed, the DTCs should be cleared from the memory of the PCM. Technician B says that serial data can be helpful when there are no DTCs but there is a fault in the system. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While discussing quick-disconnect fuel line fittings: Technician A says that some quick-disconnect fittings may be disconnected with a pair of snapring pliers. Technician B says that some quick-disconnect fittings are hand releasable. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While discussing testing OBD II system components: Technician A says that a testlight can be used to test O2S output. Technician B says that a digital voltmeter can be used to test the O2S. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While discussing the misfire monitor: Technician A says that while detecting type A misfires, the monitor checks cylinder misfiring over a 500-revolution period. Technician B says that while detecting type B misfires, the monitor checks cylinder misfires over a 1,000-revolution period. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
While discussing the various fuel filters used in current automobiles: Technician A says that all systems have a vapor separator that prevents gaseous fuel from being sent to the fuel pump. Technician B says that fuel systems have a strainer located in the fuel tank that prevents large contaminants from entering the fuel system. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
b. Technician B
Which of the following statements about a fuel volume test is not true? a. This test measures the flow rate of the pump and can help isolate fuel system restrictions or weak pumps. b. The test is conducted by collecting the fuel dispensed by the certain during a period of time, normally 5 seconds. c. The flow of fuel into the container should be smooth and continuous with no signs of air bubbles. d. Poor results may indicate a bad pump or restrictions in the delivery system.
b. The test is conducted by collecting the fuel dispensed by the certain during a period of time, normally 5 seconds.
Technician A says a loose gas cap can cause the "check engine" light to turn on. Technician B says a faulty gas cap can turn on the "check engine" light. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
Technician A says that higher than normal pressure from an electric fuel pump can be caused by a faulty pressure regulator. Technician B says that the typical problem may be an obstructed return line. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
To relieve fuel pressure on an EFI car: Technician A connects a pressure gauge to the fuel rail. Technician B disables the fuel pump and runs the car until it dies. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
When testing a frequency varying MAF: Technician A says that the frequency should increase with an increase in engine speed. Technician B says that when observed on a lab scope, the signal from the sensor should be a square wave. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While diagnosing the cause of a hard starting condition: Technician A checks the ECT sensor. Technician B checks the MAP sensor. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing ECT sensor diagnosis: Technician A says that a defective ECT sensor may cause hard cold engine starting. Technician B says that a defective ECT sensor may cause improper operation of emission control devices. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing TP sensor diagnosis: Technician A says that a four-wire TP sensor contains an idle switch. Technician B says that in some applications, the TP sensor mounting bolts may be loosened and the TP sensor housing rotated to adjust the voltage signal with the throttle in the idle position. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing monitoring systems: Technician A says that the fuel system monitor checks the short-term and long-term fuel trims. Technician B says that the heated oxygen sensor monitoring system checks lean-to-rich and rich-to-lean response times. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
While discussing the catalyst efficiency monitor: Technician A says that if the catalytic converter is not reducing emissions properly, the voltage frequency increases on the downstream HO2S. Technician B says that if a fault occurs in the catalyst monitor system on three drive cycles, the MIL will be illuminated. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
c. Both A and B
Technician A says that when going to high altitudes, engines produce lower power. Technician B says that most engine control systems can compensate the air-fuel mixture for changes in altitude. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and d. Neither Technician A nor B
c. Both Technicians A and B
The fuel pressure drops rapidly when the engine is turned off. Technician A says that one or more injectors could be leaking. Technician B says that a defective check valve in the fuel pump could be the cause. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B
c. Both Technicians A and B
A fuel filter has been accidentally installed backwards. What is the most likely result? a. Nothing will be noticed b. Reduced fuel economy c. Lower power at higher engine speeds and loads d. Fuel system pulsation noises may be heard
c. Lower power at higher engine speeds and loads
A TP sensor is what type of sensor? a. Rheostat b. Voltage generating c. Potentiometer d. Piezoelectric
c. Potentiometer
Which of the following memory circuits is used to store trouble codes and other temporary information? a. Read-only memory b. Programmed read-only memory c. Random access memory d. All of the above
c. Random access memory
If fuel pump pressure or volume is less than specified, which of the following is not a likely cause of the problem? a. A restricted fuel filter b. A faulty fuel pump c. Restricted fuel return lines d. Restricted fuel supply lines
c. Restricted fuel return lines
Which of the following statements is not true? a. DTCs that will not affect emissions will never illuminate the MIL. b. An active or current DTC represents a fault that was detected and occurred during two trips. c. When a two-trip fault is detected for the second time, a DTC is stored as a pending code. d. There are some DTCs that will set in one trip.
c. When a two-trip fault is detected for the second time, a DTC is stored as a pending code.
Low fuel pressure can be caused by all of the following except___. a. a clogged fuel filter b. a restricted fuel line c. a fuel pump that draws too high amperage d. a dirty filter sock in the tank
c. a fuel pump that draws too high amperage
A computer is capable of doing all of the following except___. a. receive input data b. process input data according to a program and monitor output action c. control the vehicle's operating conditions d. store data and information
c. control the vehicle's operating conditions
Vapor lock can occur __________________. a. as a result of excessive heat near fuel lines b. if a fuel line is restricted c. during both a and b d. during neither a nor b
c. during both a and b
Air that enters the engine without passing through the air flow sensor is called ____________. a. bypass air b. dirty air c. false air d. measured air
c. false air
A defective IAT sensor or circuit may cause the following problems, except ___. a. hard engine starting b. rich or lean air-fuel ratio c. improper converter clutch lockup d. reduced fuel economy
c. improper converter clutch lockup
What can be used to measure the alcohol content in gasoline? a. Graduated cylinder b. Electronic tester c. Scan tool d. Either a or b
d. Either a or b
Which sensor does the TP sensor backup if the PCM determines that a failure has occurred? a. Oxygen sensor b. MAF sensor c. MAP sensor d. Either b or c
d. Either b or c
Technician A says that the oxygen sensor provides the major input during the open-loop mode. Technician B says that the coolant temperature sensor input is not used during open-loop mode operation. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
d. Neither A nor B
While discussing OBD II systems: Technician A says that the PCM illuminates the MIL if a defect causes emission levels to exceed 2.5 times the emission standards for that model year vehicle. Technician B says that if a misfire condition threatens engine or catalyst damage, the PCM flashes the MIL. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
d. Neither A nor B
While discussing the MIL on OBD II systems: Technician A says that the MIL will flash if the PCM detects a fault in a sensor or circuit. Technician B says that as soon as the PCM has detected a fault, it will turn on the MIL. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
d. Neither A nor B
While discussing zirconium O2S diagnosis: Technician A says that the voltage signal on a satisfactory O2S should always be cycling between 0.5 volt and 1 volt. Technician B says that a contaminated O2S may produce a continually high voltage signal. Who is correct? a. Technician A b. Technician B c. Both A and B d. Neither A nor B
d. Neither A nor B
Which sensor is used to measure the position of the throttle? a. O2S b. ECT sensor c. Engine MAP sensor d. TP sensor
d. TP sensor
Fuel injectors can be tested using ___________. a. an ohmmeter b. a stethoscope c. a scope d. all of the above
d. all of the above
The MAF sensor is used mostly by the PCM to determine the amount of ________ to deliver to the engine. a. vacuum correction b. idle air c. spark advance d. fuel
d. fuel
