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UPDATED MICHIGAN ENGINE REPAIR MECHANIC
STUDY QUESTIONS AND 100% CORRECT ANSWERS
“Winter blend gasoline ________. can cause engine driveability problems if used during warm weather. has a higher RVP. vaporizes more easily than summer blend gasoline.
All of the above. - CORRECT ANSWER All of the above"
"Vapor lock can occur ________. as a result of excessive heat near fuel lines. if a fuel line is restricted. during both A and B.
during neither A nor B. - CORRECT ANSWER during both A and B."
"E85 means that the fuel is made from ________. pure ethyl alcohol ethanol that has 15% water 85% gasoline, 15% ethanol
85% ethanol, 15% gasoline - CORRECT ANSWER 85% ethanol, 15% gasoline"
"A flex-fuel vehicle can be identified by ________. VIN VECI emblems on the side, front, and/or rear of the vehicle
Any of the above - CORRECT ANSWER Any of the above"
"Coil polarity is determined by the ________. direction of lamination turns ratio direction of the coil windings
saturation direction - CORRECT ANSWER direction of the coil windings"
"How does a waste-spark ignition system fire the spark plugs?
The polarity reverses at each firing (flip flops) The same plug always is fired straight or reverse polarity The waste spark is sent to the cylinder next to the cylinder being fired
Both A and C - CORRECT ANSWER The same plug always is fired straight or reverse polarity"
"The pulse generator ________. fires the spark plug directly signals the computer that fires the spark plug directly is used as a tachometer reference signal by the computer and has no other function
signals the electronic control unit (module) - CORRECT ANSWER signals the electronic
control unit (module)" "Two technicians are discussing distributor ignition. Technician A says that the pickup coil in the distributor is used to pulse the ignition module (igniter). Technician B says that some distributor
ignition systems use a Hall-effect system. Which technician is correct? - CORRECT ANSWER
Both technicians" "Technician A says that a two-wire COP system uses the PCM to trigger the coil. Technician B says that a three-wire COP system has an ignition module built into the coil assembly. Which
technician is correct? - CORRECT ANSWER Both technicians"
"The ignition system is usually divided into ________ different sections four one three
two - CORRECT ANSWER two"
"What unit of electricity is used as a signal for a computer? Watt Ohm Ampere
Volt - CORRECT ANSWER Volt"
"The four basic computer functions include ________. data gathering, processing, output, and evaluation input, processing, storage, and output sensing, calculating, actuating, and processing
Baud rate Pulse width modulation
Oscillator speed - CORRECT ANSWER Baud rate"
"The sensor that measures the temperature of the air being drawn into the engine is called a(n) ________. IAT NTC thermistor PTC thermistor
Both A and B - CORRECT ANSWER Both A and B"
"What type of sensor is used to measure the position of the throttle? Potentiometer Engine speed (RPM) Positive temperature coefficient (PTC) thermistor
Negative temperature coefficient (NTC) thermistor - CORRECT ANSWER Engine speed
(RPM)"
"Typical TP sensor voltage at idle is about ________. 1.5 to 2.8 volts 2.5 to 2.8 volts 0.5 volt or 10% of WOT sensor voltage
13.5 to 15.0 volts - CORRECT ANSWER 0.5 volt or 10% of WOT sensor voltage"
"Most TP sensors have how many wires? 1 2 3
4 - CORRECT ANSWER 3"
"Which of these sensors does the TP sensor back up if the PCM determines that a failure has occurred? Oxygen sensor MAF sensor MAP sensor
Either B or C - CORRECT ANSWER MAF sensor"
"Which of these tools would be used to test a MAP sensor? A test light A vacuum simulator A digital voltmeter
A jumper wire - CORRECT ANSWER A digital voltmeter"
"When the engine is at idle speed, manifold vacuum is ________. high (17 to 21 in. Hg) low (1 to 4 in. Hg) fluctuating from 8 to 10 in. Hg
zero - CORRECT ANSWER high (17 to 21 in. Hg)"
"When measuring the output signal of a MAP sensor on a General Motors vehicle, the digital multimeter should be set to read ________. DC volts frequency in Hz DC amperes
AC volts - CORRECT ANSWER DC volts"
"The output of a MAP sensor is reading 1.0 volt. What is the approximate engine vacuum in inches of mercury (Hg)? 5 10- 0
17-21 - CORRECT ANSWER 17-21"
"A scan tool can be used to test a MAP sensor by monitoring the injector pulse width (in milliseconds) while ________ is being applied to the MAP sensor air pressure voltage ground
vacuum - CORRECT ANSWER vacuum"
"The MAP sensor is used by the PCM to diagnose the ________ system.
"A wide band oxygen sensor is capable of detecting the air-fuel mixture in the exhaust from ________ (rich) to ________ (lean). 12:1; 15: 13:1; 16.7: 8:1; 18:
10:1; 23:1 - CORRECT ANSWER 10:1; 23:1"
"The oxygen sensor signal is used by the PCM to ________ the air-fuel mixture. dampen add fuel to fine-tune
add air to - CORRECT ANSWER fine-tune"
"A wide-band oxygen sensor has an internally damaged heater circuit. What could this cause? Could cause the engine to run in open loop only The oxygen sensor will leak air into the exhaust manifold It may not set a DTC
Could cause the engine to run rich - CORRECT ANSWER It may not set a DTC"
"A wide band oxygen sensor needs to be heated to what operating temperature? 1,400 deg. F 800 deg. F 2,000 deg. F
600 deg. F - CORRECT ANSWER 1,400 deg. F"
"Where is sensor 1, bank 1 located on a V-type engine? On the same bank where number 1 cylinder is located Before the catalytic converter On the bank opposite cylinder number 1
Both A and B - CORRECT ANSWER On the same bank where number 1, cylinder is located
Before the catalytic converter" "You have checked the crankshaft and found the following measurements below the rod journal
surfaces are smooth no rod journal taper is present - CORRECT ANSWER Install standard
bearings in all rods"
"You have measured all the cylinders and obtained the measurements given below all the
cylinders are smooth and the pistons are reusable what should the mechanic do? - CORRECT
ANSWER Deglaze the pistons use original pistons and new standard rings"
"Crank shaft end play can be checked with - CORRECT ANSWER A dial indicator"
"The picture below shows a mechanic measuring - CORRECT ANSWER Valve guide end
wear"
"You are performing a compression test which one of these are true - CORRECT ANSWER
The throttle and choke must be opened fully"
"Which one of the following is a sad grade 5 bolt - CORRECT ANSWER C - the 3 lines on the
bolt" "CYLINDER DIAMETER IS IMPORTANT WHEN DETERMINING RING END GAP. AS A RULE OF
THUMB, A 3 INCH BORE WOULD REQUIRE A RING END GAP OF APPROXIMATELY: -
CORRECT ANSWER .009 .0012"
"Cylinder rings should be checked for fit - CORRECT ANSWER Both a and b"
"When putting a engine together you would use short pieces of the hose to protect the -
CORRECT ANSWER Rod journals"
"Which one of the following will cause oil consumption - CORRECT ANSWER EXCESSIVE
MAIN BEARING CLEARANCE."
"Before installing the pistons in a newly honed cast iron block you should clean the bores with -
CORRECT ANSWER Soap and warm water"
"Pistons for a v6 engine are generally - CORRECT ANSWER Interchangeable from one
cylinder bank to the other"
"To much crank case blow by is likely caused by - CORRECT ANSWER Worn piston rings"
"Which of the following will not be affected when free placing pistons 1 and 2 - CORRECT
ANSWER Engine timing"
"Which of the following is the proper way to install camshaft bearings - CORRECT ANSWER
Drive them into place with a camshaft bearing driver"
"Which of the following is not a recommended break in practice for an over hauled engine -
CORRECT ANSWER Run the engine at idle with no load for the first few hours"
"After cleaning the ring grooves of a piston you then should check the top ring groove for wea.
What do you measure this with - CORRECT ANSWER A feeler gauge and a new piston ring"
"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? - CORRECT ANSWER Both technicians"
"Technician A says that the research octane number is higher than the motor octane number. Technician B says that the octane rating posted on fuel pumps is an average of the two ratings.
Which technician is correct? - CORRECT ANSWER Both technicians"
"Technician A says that in 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? - CORRECT ANSWER Both technicians"
"What can be used to measure the alcohol content in gasoline? Electronic Tester Graduated cylinder Scan tool
Either A or B - CORRECT ANSWER Either A or B"
"The gasoline burned inside the internal combustion engine is a type of ________. hydrocarbon alcohol carbon monoxide
compressed vapor - CORRECT ANSWER hydrocarbon"
"Avoid topping off the fuel tank because ________. the extra fuel simply spills onto the ground. the extra fuel goes into the expansion area of the tank and is not used by the engine. it can saturate the charcoal canister.
the extra fuel increases vehicle weight and reduces performance. - CORRECT ANSWER it can
saturate the charcoal canister" "Using ethanol-enhanced or reformulated gasoline can result in ________. the same fuel economy compared to using 100% gasoline. improved fuel economy compared to using 100% gasoline. reduced fuel economy compared to using 100% gasoline.
higher or lower fuel economy, depending on the size of the engine. - CORRECT ANSWER
reduced fuel economy compared to using 100% gasoline." "Pump octane is rated by ________. research octane only an average of these two methods motor octane only
None of these - CORRECT ANSWER an average of these two methods"
"Ethanol can be produced from what products? Sugarcane Switchgrass Corn
Any of the above - CORRECT ANSWER Any of the above"
"Which alcohol is dangerous (toxic)? Ethanol Neither ethanol nor methanol Both ethanol and methanol
Methanol - CORRECT ANSWER Methanol"
"Which is the most widely used alternative fuel? M Propane E
CNG - CORRECT ANSWER Propane"
"Liquefied petroleum gas (LPG) is also called ________. Propane E
"A reluctor is a ________. notched ring or pointed wheel type of sensor used in the secondary circuit type of Hall-effect sensor
type of optical sensor - CORRECT ANSWER notched ring or pointed wheel"
"HEI and EIS are examples of ________. distributor ignition systems waste-spark systems pickup coil types
coil-on-plug systems - CORRECT ANSWER distributor ignition systems"
"A spark tester should be used to check for spark because ________. it can detect the gap of the spark plugs it is connected to the CKP sensor to check its output a spark tester requires at least 25,000 volts to fire
it can detect a cracked spark plug - CORRECT ANSWER a spark tester requires at least 25,
volts to fire" "Poor engine performance could be the result of a ________. distributor ignition with the CMP and CKP not correctly indexed defective coil a high-voltage spark leak
Any of the above - CORRECT ANSWER Any of the above"
"Typical primary coil resistance specifications usually range from ________ ohms less than 1 to 3 6,000 to 30, 500 to 1500
100 to 450 - CORRECT ANSWER less than 1 to 3"
"Typical secondary coil resistance specifications usually range from ________ ohms 6,000 to 30, 1 to 3 100 to 450
500 to 1500 - CORRECT ANSWER 6,000 to 30,000"
"What should be inspected as part of a visual inspection of the ignition system? Spark plug gap Coil polarity Spark plug wires for proper routing
All of the above - CORRECT ANSWER Spark plug wires for proper routing"
"What part of the scope pattern show the duration of the spark? Dwell section Firing line Intermediate section
Spark line - CORRECT ANSWER Spark line"
"Which can be used to test for a fault with a cylinder on a waste-spark system? Using short sections of rubber hose attached to the coil terminals An LED test light Using a timing light to check for spark
Any of the above - CORRECT ANSWER Using short sections of rubber hose attached to the
coil terminals" "As engine speed increases, the timing of the spark in the cylinder must be ________, maintained the same retarded slightly set at 10 degrees BTDC
advanced - CORRECT ANSWER advanced"
"Which sensor produces a square waveform? Magnetic sensor Pickup coil Hall-Effect sensor
Both B and C - CORRECT ANSWER Hall-Effect sensor"
"Which of these components sends a pulse signal to an electronic ignition module? Resistor Pickup coil Coil wire
Ignition coil - CORRECT ANSWER Pickup coil"
DC volts
Ohms - CORRECT ANSWER Ohms"
"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? 230°F (110°C) 120°F (50°C) -40°F (-40°C)
284°F (140°C) - CORRECT ANSWER -40°F (-40°C)"
"A typical IAT or ECT sensor reads about 3000 ohms when tested using a DMM. This resistance represents a temperature of about ________. 284° F (140°C) -40° F (-40°C) 70° F (20°C)
120° F (50°C) - CORRECT ANSWER 70° F (20°C)"
"If the transmission fluid temperature (TFT) sensor indicates cold automatic transmission fluid, what would the PCM do to the shifts? Disable torque converter clutch; normal shift points Normal shifts but overdrive will be disabled Delayed shift points and torque converter clutch disabled
Normal shifts and normal operation of the torque converter clutch - CORRECT ANSWER
Delayed shift points and torque converter clutch disabled" "What happens to the voltage measured at the ECT sensor when the thermostat opens? Decreases about 1 volt Increases slightly Decreases slightly
Increases about 1 volt - CORRECT ANSWER Increases slightly"
"All of the following are approved methods or tools used when diagnosing an ECT (engine coolant temperature) sensor EXCEPT ________. digital multimeter (DMM) substituting a variable resistor scan tool
observing resistance values at a specified temperature - CORRECT ANSWER substituting a
variable resistor" "Which wire on a typical TP sensor should back-probed to check the voltage signal to the PCM? Ground wire Signal wire Meter should be connected between 5-volt reference and ground
5-volt reference (Vref) - CORRECT ANSWER Signal wire"
"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 The TP sensor signal is shorted to 5-volt reference The TP sensor is shorted
Both B and C are possible - CORRECT ANSWER The TP sensor is open at one point during the
test" "The TP sensor affects the operation of all of these, EXCEPT ________. air-conditioning compressor clutch operation correcting for rich and lean air-fuel mixtures torque converter clutch operation
clear flood mode operation - CORRECT ANSWER correcting for rich and lean air-fuel
mixtures" "A typical TP sensor registers about how many volts at WOT (wide open throttle)? 13- 1.3-3.
0.5 - CORRECT ANSWER 4.5"
"The third terminal of a potentiometer is attached to a movable contact that slides across the resistor to vary ________. vacuum signal voltage spark voltage
cable tension - CORRECT ANSWER signal voltage"
"What voltage will be measured at terminal "C" as shown?
"If the MAF sensor fails, the PCM uses ________ to calculate fuel delivery needs. RPM alone RPM and throttle position throttle position and transmission RPM
MAP and throttle position - CORRECT ANSWER RPM and throttle position"
"Air that enters the engine without passing through the air flow sensor is called ________. dirty air false air bypass air
measured air - CORRECT ANSWER false air"
"Which of the following components measures the volume and density of the incoming air? Mass Air Flow Sensor Throttle Position Sensor Manifold Absolute Pressure Sensor
Oxygen Sensor - CORRECT ANSWER Mass Air Flow Sensor"
"What are the two methods of sensing incoming engine air flow? Mass air flow and air intake Speed density and mass air flow Speed density and throttle position
EGR and positive crankcase ventilation - CORRECT ANSWER Speed density and mass air
flow" "Which of these can be used to measure the frequency (Hz) output of the MAF sensor and compare the reading with specifications? DMM (digital multimeter) Megohmmeter High impedance test light
Logic Probe - CORRECT ANSWER DMM (digital multimeter)"
"MAF sensor electrical connectors should be checked for all of these, EXCEPT ________. over-tight connectors terminals bent or pushed out of the plastic connector frayed wiring
corrosion - CORRECT ANSWER over-tight connectors"
"A vehicle runs fine when in reverse yet has a rough idle and stalling when put in drive. This could be caused by ________. incorrect idle speed a missing spark plug excessive fuel pressure
a cracked air inlet hose - CORRECT ANSWER a cracked air inlet hose"
"The voltage output of a zirconia oxygen sensor when the exhaust stream is lean (excess oxygen) is ________. about in the middle of the voltage range relatively high (close to 1 volt) relatively low (close to 0 volt)
Either A or B, depending on atmospheric pressure - CORRECT ANSWER relatively low (close
to 0 volt)" "What does the post, or downstream, oxygen sensor (HO2S) measure? Amount of oxygen in front of the catalytic converter Amount of H2O in front of the catalytic converter Amount of oxygen behind the catalytic converter
Amount of H2O behind the catalytic converter - CORRECT ANSWER Amount of oxygen
behind the catalytic converter"
Which of the following is true about adjusting valve tappet clearance - CORRECT ANSWER IT
SHOULD HE ADJUSTED AT TDC AT THE END OF THE COMPRESSION STOKE"
"THE HYDRAULIC LIFTERS ARE NOISY AT HIGHWAY SPEEDS BUT QUIET AT LOW SPEEDS.
WHAT SHOULD YOU DO FIRST AS YOU DIAGNOSE THIS PROBLEM? - CORRECT ANSWER
Check crank case oil level"
"The valve timing on most engines is controlled by - CORRECT ANSWER A belt chain or gear
drive" "THE BEARING INSERTS BELOW HAVE BEEN PLASTIGAGED. WHAT CAN YOU DETERMINE
ABOUT THESE PICTURES? - CORRECT ANSWER Na"
"The compression test has showed that the middle two cylinders on one side of the v8 engine had readings of 50psi the other cylinders had readings of 135psi and 140 psi what is the likely cause of
this condition - CORRECT ANSWER A blown head gasket"
