BLOCK B: Engine Systems. Flashcards
1
Q
When an automobile engine run without a thermostat, Which of the following conditions would be most likely to result? a. Higher HC and CO emissions'. b, Higher NOx emission. c. Engine overheat. d. Poor acceleration
A
a. Higher HC and CO emissions’.
2
Q
Testing an engine coolant temperature sensor shows 100 000 ohms resistance at -40 Celsius and 70 ohms at 130 Celsius. What does this indicate?
a. The sensor is functioning normally within its design limits.
b. The sensor circuit is shorted in the power-train control module.
c. The sensor is shorted when hot, bypassing all controls.
d. The engine coolant temperature sensor has ground fault
A
a. The sensor is functioning normally within its design limits.
3
Q
The capacity of a cooling system is 9.5 liters. Which antifreeze mixture will provide adequate protection for winter, at the lowest cost?
a. 2.5L of coolant and 7L of distilled water
b. 3.5L of distilled water and 6.0L of coolant
c. 5.0L of coolant and 4.5L of distilled water
d. 6.5L of coolant and 3.0L of distilled water.
A
c. 5.0L of coolant and 4.5L of distilled water
4
Q
A customer reports that coolant is being lost. Coolant was recently added to a hot engine. The customer now notices white smoke from the exhaust when the engine is loaded. During a cooling system pressure test, the pressure drops slowly but no external leaks are seen. What is the problem?
a. The intake manifold is leaking into the crankcase.
b. The cylinder head gasket is leaking, pressurizing the cooling system.
c. The transmission cooler is leaking coolant into the transmission.
d. The cylinder head has cracked and is leaking coolant into the combustion chamber
A
d. The cylinder head has cracked and is leaking coolant into the combustion chamber
5
Q
What shape is a cold cam- ground piston?
a. Tapered.
b. Round.
c. Slightly oval.
d. Slightly flared.
A
c. Slightly oval.
Elliptical in shape.
6
Q
What happens to a Plastigage strip when friction-bearing clearance decreases?
a. It changes colour.
b. It becomes wider.
c. It remains unchanged.
d. It becomes narrower.
A
b. It becomes wider.
7
Q
When an interference angle is faced to a valve, it would be:
a. 1 degree
b. 2 degrees.
c. 5 degrees.
d. 10 degrees
A
a. 1 degree.
When an interference angle is cut to a valve, it is almost ALWAYS 1 degree.
8
Q
An oil pressure test reveals low oil pressure at idle and lower than expected oil pressure at 2500 rpm. What do these results indicate?
a. The oil pump pressure relief valve is stuck closed.
b. There is a leak in the oil filter.
c. There is significant wear in the engine bearings.
d. The oil return passages are plugged and the engine is starved of oil.
A
c. There is significant wear in the engine bearings
9
Q
What is indicated by the results below from engine compression and cylinder leakage tests?
Compression Cylinder Leakage.
Cyl 1 145 psi 49%
Cyl 2 157 psi 51%
Cyl 3 167 psi 68%
Cyl 4 150 psi 60%
a. The rings are worn in all cylinders.
b. Valve seals and valve guides are leaking.
c. The timing chain is loose and has jumped.
d. Valve sealing is poor in all cylinders.
A
a. The rings are worn in all cylinders.
10
Q
An engine is described as being "sluggish". The vacuum reading at idle is 17" Hg. On a snap throttle test, the vacuum drops to 8" Hg then rebounds to 18" Hg. The vacuum reading drops off slowly when the engine is held at 2500 rpm. What do these results indicate? a. A stretched timing chain b. A burned exhaust valve c. A restricted exhaust system A rich fuel/air mixture
A
c. A restricted exhaust system
11
Q
A tech has identified a cooling system leak in the radiator. The leak is isolated in the radiator core. What repairs should be done?
a. The radiator should be flushed and then refilled with good quality coolant.
b. The radiator should be cleaned and then repaired by crimping the leaking tube.
c. The radiator core should be repaired or replaced and then refilled with good quality coolant.
d. The affected tubes of the core should be isolated and then abandoned.
A
c. The radiator core should be repaired or replaced and then refilled with good quality coolant.
12
Q
While pressure testing a cooling system, a tech notices a leak from the water pump. What should be done?
a. Drain the system, remove the pump drive belt and the timing belt if required, replace the water pump, then refill and bleed the system.
b. Drain the system, fill the hole with silicone, refill and retest for further leakage.
c. Check the oil for coolant contamination. If present, replace the engine.
d. Flush the cooling system, replace the water pump, add coolant conditioner and leak stopping material to the system.
A
a. Drain the system, remove the pump drive belt and the timing belt if required, replace the water pump, then refill and bleed the system
13
Q
What is the procedure to check the coolant serviceability?
a. The coolant should be drained, then the correct volume of a 50% solution installed.
b. Coolant should be checked for pH level using a voltmeter, for electrolytic level using an ohmmeter, and for concentration using a hydrometer.
c. A coolant additive package should be added to restore the coolant quality before testing.
d. Coolant should be checked for pH level using a test strip, for electrolytic level using a voltmeter, and for concentration using a refractometer.
A
d. Coolant should be checked for pH level using a test strip, for electrolytic level using a voltmeter, and for concentration using a refractometer.
14
Q
A tech finds that the clearances in the oil pump are excessive. What repairs should be done?
a. The rotors or gears should be replaced and the bore resized.
b. Install a larger relief spring and an oil filter bypass valve.
c. The complete pump assembly should be discarded and replaced.
d. A larger gear set should be installed and the system pressure checked.
A
c. The complete pump assembly should be discarded and replaced
15
Q
What must be done if the crankshaft end-play exceeds specification?
a. replace crankshaft.
b. Machine the crankshaft thrust faces.
c. Shim the crankshaft.
d. Replace the thrust bearing.
A
d. Replace the thrust bearing.
16
Q
What is the correct tool(s) for measuring a cylinder head for warpage?
a. Dial indicator and magnetic base.
b. Straight edge and feeler gauge.
c. Outside micrometer.
d. Dial bore gauge.
A
b. Straight edge and feeler gauge.
17
Q
What is the correct procedure to install a 0.020” oversize piston?
a. Bore the cylinder to 0.020” oversize, then hone to provide a suitable finish.
b. Subtract the clearance required, bore the cylinder to that size, then hone for clearance.
c. Measure the piston, bore the cylinder to actual piston size, then hone for clearance.
d. Bore the cylinder to 0.022” to provide clearance, then hone to a suitable finish.
A
c. Measure the piston, bore the cylinder to actual piston size, then hone for clearance.
18
Q
When installing new bearings, what should be done to verify bearing clearance during final assembly?
a. Look for cast codes on the counterweights of the crankshaft and install bearing shells to match.
b. Look on the back of the original bearing shells for size information and install new shells of the same size.
c. Measure the bore diameter to determine oversize required and the journal diameter to determine the undersize required.
d. Install replacement bearings and use “Plastigage” to measure the installed clearance.
A
d. Install replacement bearings and use “Plastigage” to measure the installed clearance.
19
Q
A multiport V6 engine is running rough and appears to be starved for fuel on two of three cylinders on a bank-fire injection system. Adding propane seems to improve the idle and drivability. A cylinder balance test indicates low power contribution from cylinders 1 and 5. Further testing proves there are no vacuum leaks. What causes this condition?
a. The powertrain control module has a failing injector driver.
b. Restricted injectors on cylinders 1 and 3
c. An open in the injector winding of cylinder 3
d. An injector with low resistance in cylinder 3
A
d. An injector with low resistance in cylinder 3
20
Q
A vehicle with port injection is hard to start after sitting for an hour or more. A fuel pressure test shows that the fuel pressure is normal, but quickly drops to zero after the engine is turned off. What causes this condition?
a. A defective fuel pump
b. A plugged fuel injector
c. A defective fuel pump check valve
d. Fuel pressure regulator stuck closed.
A
c. A defective fuel pump check valve
21
Q
A vehicle equipped with a distributor ignition system is hard starting when cold. Which of the following conditions would cause this?
a. Spark plugs gapped too closely
b. Poorly grounded ignition module
c. Wires installed on distributor cap incorrectly
d. An open coil wire to the distributor cap
A
a. Spark plugs gapped too closely
22
Q
The engine idles poorly but runs fine at 2000 rpm. What is the cause? Scan Tool Idle 2000 rpm TPS 0.7 volts 1.5 volts CTS 76 deg 76 deg MAP 83 kPa 31 kPa HO2S Varying from 725-900mV Varying from 225-900mV RPM 550 2050 IAC 50 20 a. The engine is running rich. b. The EGR valve is not seating. c. One or more injectors are clogged. d. The engine is overheating.
A
b. The EGR valve is not seating.
23
Q
A tech performing an emission test finds high CO and HC. Which test would confirm a suspected defective catalytic converter?
a. Outlet temperature would be notably higher than inlet temperature.
b. Exhaust gas back-pressure should not exist ahead of the catalytic converter.
c. Engine vacuum should stay up during a cruise check and respond quickly during a snap throttle test.
d. When the converter should not rattle when struck with a hammer.
A
a. Outlet temperature would be notably higher than inlet temperature
24
Q
After road testing for lack of power, a tech notices a hot smell from under the car and a catalytic converter that has an orange glow. What causes this condition?
a. A disconnected spark plug wire
b. A broken air pump drive belt
c. A plugged canister purge vacuum hose
d. A plugged fuel injector
A
a. A disconnected spark plug wire
25
```
A vehicle failed enhanced emissions for high oxides of nitrogen. What is causing this problem?
Scan Tool Idle
TPS 0.55 volts
CTS 80 degrees
MAP 40 kPa
HO2S Varying from 100mV-900mV
a. The engine is running too hot.
b. The MAP sensor vacuum is below 9" Hg.
c. The EGR solenoid has an open ground.
d. Fuel vapours are being drawn into the intake.
```
c. The EGR solenoid has an open ground.
26
During an enhanced I/M test, a vehicle passed the pressure test but failed the evaporative purge flow test. No DTC's were recorded. While running the vehicle with the throttle held open, the scan tool display indicates that the EVAP solenoid is commanded on. What caused the failed test?
a. EVAP solenoid shorted
b. EVAP solenoid open
c. Blocked vacuum port to solenoid
d. Vacuum leak at valve diaphragm.
c. Blocked vacuum port to solenoid.
27
When a cylinder head valve is equipped with 2 valve springs, what else should be true?
a. Coil thickness must be identical.
b. Both must have the same spring rate.
c. They are wound oppositely.
d. Valve rotators must be used.
c. They are wound oppositely.
28
```
A vehicle failed an enhanced emission test for high HC. The readings were obtained during an exhaust analysis, with the Air Injection Reaction system disabled. What is causing the problem?
Scan Tool: Idle 2000 rpm
HC 660 ppm 69 ppm
CO 0.0 % 0.22 %
CO2 10.9 % 13.9 %
O2 2.1 % 0.1 %
a. Defective catalytic converter
b. A grounded ignition wire
c. A leaking power brake booster
d. Base timing is retarded 3 degrees.
```
c. A leaking power brake booster
29
When installing a fuel pressure tester on a multiport fuel injection system, what procedure must be followed to obtain accurate pressure readings?
a. Relieve the rail pressure, then install and bleed the gauge.
b. Install the gauge, then relieve the pressure in the line.
c. Disconnect the fuel line, then install the gauge.
d. Remove the power fuse, then bleed out air in the line.
.
a. Relieve the rail pressure, then install and bleed the gauge
30
A fuel pump is suspected of being faulty. What is a quick check to confirm the fuel pump relay is working?
a. Test for power at the pump and then cycle the ignition key off.
b. Back probe the relay terminal with a test light, then cycle the key on.
c. Install a scan tool, and then check the data stream.
d. Remove the fuel pump relay, then feel for a click.
b. Back probe the relay terminal with a test light, then cycle the key on.
31
What is the procedure for diagnosing a no-start condition in a multiport fuel injected vehicle?
a. First determine there is no injector pulse or spark, then test for an open circuit at the crankshaft position sensor.
b. First test the battery voltage level, then inspect the spark wires with a high impedance digital ohmmeter.
c. First confirm the complaint, then test the fuel system pressure and compare to specs.
d. First install the scan tool, then perform a bidirectional test to fire the spark plugs.
a. First determine there is no injector pulse or spark, then test for an open circuit at the crankshaft position sensor.
32
What is indicated by the cylinder hear bolt torque specifications shown?
Initial pass 30Nm
2nd pass 65 degrees
a. Head bolts must be torqued to 30Nm, them warm the engine to 65 degrees before retorquing to 30Nm.
b. All head bolts must first be torqued to 30Nm, then all turned another 65 degrees.
c. Each head bolt must be torqued to 30Nm, then immediately turned another 65 degrees.
d. Head bolts must be torqued to 30Nm, bring the engine to full operating temperature, then turn the bolts another 65 degrees.
b. All head bolts must first be torqued to 30Nm, then all turned another 65 degrees.
33
Which procedure describes the process for replacing an exhaust gas recirculation valve?
a. Ensure the valve is cool then torque the bolts to specs.
b. Ensure the passage is open, then operate the valve.
c. Ensure the valve is the correct type, then clear the passage in the intake.
d. Ensure the passage is blocked, then replace with the correct valve.
c. Ensure the valve is the correct type, then clear the passage in the intake.
34
When testing fuel control system response by creating a vacuum leak, what two things should be observed?
a. A voltage drop in O2 sensor output and an increase in injector dwell.
b. A voltage rise in O2 sensor output and a decrease in injector dwell.
c. A decrease in RPM and an advance in spark timing.
d. An increase in RPM and a drop in spark advance.
a. A voltage drop in O2 sensor output and an increase in injector dwell.
"vacuum will create increase oxygen in the exhaust as seen by the o2 sensor and the ecm will add fuel."
35
A cylinder compression test will detect all of the following problems EXCEPT:
a. Valve not seating
b. Worn valve guides
c. Broken piston ring
d. Leaking head gasket
b. Worn valve guides
36
The first step in diagnosing a performance or drivability issue is to:
a. Perform a preliminary inspection
b. Verify the problem with a road test
c. Look for specific information from the customer
d. Eliminate the possibility of an internal engine problem.
c. Look for specific information from the customer.
37
When using a timing light to isolate an engine noise, expect top end noises to occur:
a. With every other flash of the timing light
b. With every flash of the timing light
c. Twice for every flash of the timing light
d. Between each flash of the timing light
c. Twice for every flash of the timing light
38
When performing a manifold vacuum test, raising the engine speed off idle will cause gauge readings to:
a. Increase slightly
b. Decrease slightly
c. Fluctuate rapidly
d. Remain constant.
a. Increase slightly
39
During a compression test, a cylinder reads low on the first stroke, builds up slightly, and then level off below specification. The most likely cause would be:
a. Sticking or burned valves
b. Worn piston rings or damaged piston
c. Leaking head gasket or cracked head
d. Worn cylinder walls and excessive blow by
a. Sticking or burned valves.
40
Which test can be performed on a running engine to quickly detect internal problems?
a. Cylinder compression
b. Cylinder leakage
c. Cylinder power balance
d. Oscilloscope.
c. Cylinder power balance
41
What would be the seating ability of a cylinder with a 28 percent loss of air pressure during a leakage test?
a. Good
b. Fair
c. Poor
d. Bad
c. Poor
42
A vacuum gauge connected to an engine reads 18hg at idle. When the engine speed is increased, the gauge momentarily drops to near zero, then slowly rises and stabilizes at 9hg. The likely cause of these readings would be:
a. Weak piston rings
b. Incorrect fuel mixture
c. Restricted exhaust
d. Retarded ignition timing.
c. Restricted exhaust
43
The needle of a vacuum gauge rapidly vibrates between 14 and 18"Hg with the engine running at idle. As the engine speed increases, the gauge stops vibrating and stabilizes. These readings are most likely caused by:
a. Weak piston rings
b. Incorrect fuel mixture
c. Worn valve guides
d. Weak valve springs.
d. weak valve spring
44
A cylinder compression test reveals fairly even compression but lower than specs. A second wet test results in higher readings on all cylinders. These results indicate:
a. Poor valve seating
b. Worn valve guides
c. Worn piston rings
d. Leaking head gasket.
c. Worn piston rings
45
Which of the following is the proper procedure for performing a cylinder balance test?
a. Run the engine at idle, short the spark plug on at a time, and note any rpm drop.
b. Run the engine at 1500 rpm, short the spark plugs two and a time, and not any rpm drop.
c. Run the engine at idle, short all but two spark plugs, and not any rpm drop.
d. Run the engine at 1500 rpm, short the spark plugs one at a time, and note any rpm drop.
d. Run the engine at 1500 rpm, short the spark plugs one at a time, and note any rpm drop?
46
```
The needle on a vacuum gauge oscillates back and forth when the engine is at idle. this generally indicates which of the following?
a. Late valve timing
b. Poor air fuel mixture
c. A blown cylinder head gasket
d An air leak in the intake manifold
```
b. Poor air fuel mixture
47
After facing, the valves must have a margin of at least:
a. 1/64"
b. 1/32"
c. 1/16"
d. 1/8"
b. 1/32"
48
Resurfacing an OHC cylinder head will:
a. Increase valve timing
b. Alter cam timing
c. Change valve lash
d. Lower compression.
b. Alter cam timing
49
Valve spring installed height is measured from:
a. Spring seat to valve tip
b. Valve guide top to valve keeper groove
c. Valve retainer top to valve stem end
d. Spring seat to valve retainer.
d. Spring seat to valve retainer.
50
Which of the following method is NOT used for detecting cracks in a cast iron cylinder head?
a. Dye penetrate test
b. Pressure test
c. Magnetic particle testing
d. Leak down testing.
a. Dye penetrate test.
51
A cylinder bore measurement indicates 3.067" below ring travel at the bottom and 3.077" below ridge at the top. The standard factory bore is 3.065". What would be the proper repair?
a. Deglaze the cylinder walls and install the old piston with new cast iron rings.
b. Bore and hone the cylinder 3.097" and install 0.030" over size pistons with new rings.
c. Bore and hone the cylinder to 3.075" and install knurled pistons with new rings.
d. Bore and hone the cylinder to 3.095" and install 0.030" over size pistons with new rings.
d. Bore and hone the cylinder to 3.095" and install 0.030" over size pistons with new rings.-
52
Two cylinders bore measurements are taken: one perpendicular (at right angle) to the crankshaft and the other in line with the crankshaft. These two measurements are used to determine:
a. Cylinder out of round
b. Cylinder taper
c. Cylinder warpage
d. Cylinder ridge.
a. Cylinder out of round--
53
In a high mileage engine, cylinder wear is normally the greatest at the:
a. Top of the cylinder measured parallel to the crankshaft
b. Top of the cylinder measured at right angle to the crankshaft
c. Bottom of the cylinder measured parallel to the crankshaft
d. Bottom of the cylinder measured at right angle to the crankshaft.
b. Top of the cylinder measured at right angle to the crankshaft.
54
A diagonal or angled wear pattern on the thrust surface of a piston is an indication of:
a. A bent connecting rod
b. Too much piston pin clearance
c. An out of round cylinder bore
d. A collapsed piston skirt.
a. A bent connecting rod
55
For engine rebuilding, the use of a dial indicator is for:
a. Ring end gap
b. Piston to cylinder end gap
c. End play in a camshaft
d. Valve seat angle.
c. End play in a camshaft.
56
Vehicle engine high oil pressure can be caused by:
a. Plugged cam oil galleries
b. Pressure relief valve stuck closed
c. Pressure relief valve stuck open
d. Plugged oil filter.
b. Pressure relief valve stuck closed
57
A compression test on a vehicle is done:
a. On a cold engine
b. With a booster battery in place
c. With wide open throttle
d. With spark plug in place
c. With wide open throttle
58
A light double knocking noise while the vehicle is idling can be caused by:
a. Worn connecting rod bearings
b. Worn camshaft bushings
c. Loose piston pin
d. Broken piston skirt.
c. Loose piston pin.
59
When installing a piston assembly, the notch on the head of the piston will generally face toward:
a. The rear of the engine
b. The major thrust side
c. The front of the engine
d. The minor thrust side
c. The front of the engine
60
Which of the following may be a cause of low oil pressure?
a. Worn piston rings
b. Excessive main bearing clearance
c. Excessive valve guide clearance
d. Stretched timing chain.
b. Excessive main bearing clearance.
61
A burned valve would be best diagnosed with:
a. A compression tester
b. A vacuum gauge
c. An oil pressure gauge
d. A cooling system tester
b. A vacuum gauge.
A vacuum gauge is the best way to check for a burnt valve. Hook up the gauge to the intake manifold vacuum port and observe the needle. If the needle bounces around more than 2-3 inches HG, that engine most likely has burnt valve(s)
62
A head gasket blown between two cylinders would be best diagnosed using:
a. A vacuum gauge
b. A stethoscope
c. A cylinder leak detector
d. A black light detector
c. A cylinder leak detector.
63
Piston slap is most audible:
a. On a cold start up
b. At engine operating temperature
c. At highway speeds
d. When the spark plug is shorted out
a. On a cold start-up.
64
Piston pin noise is most audible:
a. On a cold start up
b. At engine operating temperature
c. At highway speeds
d. At idle speed
d. At idle speed.
65
Tappet noises are:
a. The same speed as crankshaft rotation
b. Twice the speed of crankshaft rotation
c. Half the speed of crankshaft rotation
d. One quarter the speed of crankshaft rotation
c. Half the speed of crankshaft rotation.
66
Piston pin noise is usually:
a. The same speed as crankshaft rotation
b. Twice the speed of crankshaft rotation
c. Half the speed of crankshaft rotation
d. One quarter the speed of crankshaft rotation
a. The same speed as crankshaft rotation.
67
A worn main bearing usually results in:
a. A decrease in oil pressure
b. A decrease in compression pressure
c. A decrease in intake manifold vacuum
d. An increase in oil pressure
a. A decrease in oil pressure.
68
A series of light accelerations on a warm and idling engine, may be used to diagnose:
a. Main bearing noise
b. Connecting rod bearing noise
c. Tappet noise
d. Piston pin noise.
b. Connecting rod bearing noise
69
Camshaft lift is the difference between:
a. Base circle diameter and lobe height
b. Journal diameter and lobe height
c. Camshaft run out and base circle diameter
d. Base circle run out and lobe height
a. Base circle diameter and lobe height
70
Checking manifold vacuum with a gauge will reveal all of the following problems except:
a. Worn valve guides
b. Exhaust restrictions
c. Worn piston rings
d. Sticking hydraulic lifters.
d. Sticking hydraulic lifters.
71
A florescent dye test is used to check for:
a. External coolant leaks
b. Internal oil leaks
c. Combustion leaking into the coolant
d. Coolant leaking into the crankcase.
a. External coolant leaks.
72
During a manifold vacuum test, a rapid needle vibration on acceleration is noticed. This can be caused by:
a. A restricted exhaust system
b. A rich air fuel ratio
c. A weak valve spring
d. Worn valves.
c. A weak valve spring.
73
Low and steady vacuum gauge readings can be caused by:
a. Worn valve guides
b. Intake manifold leak (vacuum)
c. An incorrect fuel mixture
d. An exhaust restriction
b. Intake manifold leak (vacuum)
74
An engine produces a sharp clattering knocking sound, but grounding a spark plug leak quiets the noise down. The most likely cause would be:
a. Worn main bearing
b. A loose wrist pin
c. A worn connecting rod bearing
d. A broken valve spring.
c. A worn connecting rod bearing.
75
In a cylinder compression test, if the compression is low on the first stroke and increases on the following strokes but never reaches specs, it probably means:
a. Cylinder compression is okay
b. Rings may be worn or valve may be sticking
c. Head gasket may be leaking
d. Excessive carbon build up
b. Rings may be worn or valve may be sticking.
76
If the manufacturer specifies 15 to 21"Hg of manifold vacuum at sea level, what would be the acceptable range when testing at 5000 feet of elevation?
a. 15 to 21
b. 20 to 26
c. 14 to 20
d. 10 to 16
b. 20 to 26
for every 1000 feet of elevation you loose 1" of vacuum
77
High compression readings, good cylinder leakage test results, and good power balance can be the result of:
a. Incorrect valve timing
b. Exhaust restriction
c. Carbon deposit on the piston
d. Leaking valve guide seals.
c. Carbon deposit on the piston.
78
A compression test shows that one cylinder is too low. A leakage test on that cylinder shows that there is too much leakage. During the test, air could be heard coming from the tail pipe. Which of these could be the cause:
a. Broken piston rings
b. A bad head gasket
c. A bad exhaust gasket
d. An exhaust valve not seating.
d. An exhaust valve not seating
79
Which of these would most likely cause a fuel injected engine to have low fuel pressure?
a. A clogged filter
b. A clogged fuel injector
c. A restricted fuel return line.
d. A stuck closed fuel pressure regulator
a. A clogged fuel filter.
80
The least likely cause of a bent push rod is:
a. Excessive engine rpm
b. A sticking valve
c. Excessive valve guide clearance
d. A worn rocker arm stud
c. Excessive valve guide clearance.
81
Engine design often allows the intake and exhaust valves to open together for a short period of time at the end of the exhaust stroke. This is called:
a. Duration
b. Overlap
c. Interference
d. Back pressure
b. Overlap.
82
Which of the following statements is not correct?
a. Cylinder head bolts must be tightened to the proper amount of torque in at least 3 steps.
b. Cylinder head bolts are tightened in a sequence.
c. On some engines, the head bolts are re-torqued after the engine has been run and is hot.
d. Many engines use head bolts of different lengths.
c. On some engines, the head bolts are re-torqued after the engine has been run and is hot.
83
If a large amount of material has been removed from the valve or seat during the repair procedure, the valve spring must:
a. Be stretched to compensate
b. Have new rotators installed
c. Have a shim installed
d. Be installed exactly as it was removed.
c. Have a shim installed.
84
Another method of checking valve seat contact other than valve lapping compound is to use:
a. A black light
b. A pencil or marker pen
c. Grease
d. Oil
b. A pencil or marker pen.
85
If the vacuum valve portion of a 15psi [103.4kPa] radiator cap is stuck open, which of the following is most likely to happen?
a. Leakage at the radiator tanks.
b. No coolant in the overflow reservoir.
c. Reduce system pressure.
d. Collapse upper radiator hose when engine is cold.
c.-Reduce system pressure.
86
```
If the main spring of a thermostat becomes weak or broken, which of the following is most likely to occur?
a. Engine will produce more torque.
b. Engine efficiency will increase.
c. Pre-ignition will occur.
d. Hydrocarbon emission will be
elevated.
```
c. Pre-ignition will occur.
87
```
Measured oil pressure is below specifications. Which of the following would be a likely cause?
a. Weak oil-pressure relief spring.
b. Stuck closed pressure relief valve.
c. One partially clogged camshaft
gallery.
d. Oil pump case clearance out of
specification by 0.002”[0.051mm]
```
a. Weak oil-pressure relief spring.
88
If compression values increase after performing a wet compression test on a cylinder, which engine component should be investigated for damage or failure?
a. Intake valve
b. Exhaust valve.
c. Compression rings
d. Oil control rings
C Compression rings.
89
Which of the following tools is most accurate for checking coolant strength?
a. Hydrometer
b. pH test strips.
c. Refractometer
d. Gas analyzer.
C: Refractometer is the most accurate for checking coolant strength.
90
If a horizontally mounted thermostat has a jiggle valve, at what position should the valve be placed?
a. The bottom.
b. The top.
c. The side.
d. Closest to the heater core.
b. The top.
91
When installing a new gear-type oil pump, which of the following should be done?
a. Coat the surfaces with used engine oil.
b. Apply silicone to the tips of the gear teeth.
c. Leave the oil pump dry; oil from the sump will lubricate.
d. Coat the pump with assembly lube.
d. Coat the pump with assembly lube.
92
```
Which of the following would be the most likely cause of excessive fuel pressure?
a. Restriction in the fuel supply line.
b. Excessive current supplied to fuel
pump.
c. Low engine vacuum.
d. Restriction in fuel return line.
```
d. Restriction in fuel return line.
93
A vehicle has a single cylinder misfire on a group-type injection system. Which of the following is the more likely cause?
a. Open injector PCM control circuit.
b. Blown injector fuse.
c. Inoperative [open] injector.
d. Stuck fuel-pressure regulator.
c. Inoperative [open] injector.
94
What would be the most likely cause of a loud clunking noise when accelerating in forward gear range only?
a. Broken engine mount.
b. Defective front universal joint.
c. Loose exhaust manifold.
d. Broken flex plate.
a. Broken engine mount.
95
Where should exhaust back pressure be tested in order to find a partially plugged catalytic converter?
a. At the exhaust manifold gasket.
b. At the catalytic converter front gasket.
c. Pre-catalytic oxygen sensor.
d. Post-catalytic oxygen sensor.
c. Pre-catalytic oxygen sensor.
96
Which of the following would be a likely cause of severe piston damage?
a. Retarded timing.
b. Detonation
c. Open ignition wire.
d. Over-rich mixture.
b. Detonation.
97
If measured piston ring side clearance is too great, which of the following might occur?
a. Binding during installation.
b. Inadequate oil drainage.
c. Piston wear.
d. Ring flutter.
d. Ring flutter.
98
If an air injection pump has seized, which of the following is the most likely cause?
a. Inadequate oil level.
b. Belt tension too low.
c. Defective check valve.
d. Partially open EGR valve.
c. Defective check valve.
99
During a cylinder leakage test, air is heard escaping through the oil fill. Which of the following is the correct item to investigate?
a. Piston rings
b. Intake valve.
c. Exhaust valve.
d. Head gasket
a. Piston rings.
100
Which of the following would be most likely to cause an upper radiator hose collapse on a cold engine?
a. Defective radiator cap.
b. Incorrect thermostat rating.
c. Overheating condition.
d. Empty overflow tank.
a. Defective radiator cap.
101
What would be the most likely symptom if a turbocharger wastegate was seized in the closed position?
a. No turbo boosts.
b. High-intake manifold vacuum readings.
c. Engine knocking.
d. Low NOx emission
c. Engine knocking
102
How should piston-ring groove wear be checked?
a. Measure the grooves with a machinist’s rule and compare to specification.
b. Install a new piston ring and measure with a feeler gauge between the upper surface of the ring and the land.
c. Use a depth gauge and check for depth variances around the piston.
d. Measure and compare the inside and outside diameters of the piston ring.
B: Install a new piston ring and measure with feeler gauge between the upper surface of the ring and the land.
103
When reinstalling an engine, what would most likely result from an improperly torqued transmission/transaxle bell housing?
a. Bell housing distortion.
b. Cracked engine block.
c. Rearmost engine cylinder pulled out of round.
d. Crankshaft will crack at rear main
a. bell housing distortion
104
Which of the following problems can be caused by a worn piston pin?
a. Cold engine knock.
b. Oil burning [Blue smoke emission]
c. Knocking sound that disappears when cylinder spark plug is grounded out.
d. Knocking noise that does not disappear when cylinder spark plug is grounded out.
.
d: Knocking noise that does not disappear when cylinder spark plug is grounded out
105
A vehicle has an overheating problem in slow stop-and-go traffic. Which of the following would most likely be the cause?
a. A stuck open thermostat.
b. Debris in the radiator fins.
c. Radiator cap rated at too low pressure.
d. 70/30 water to antifreeze mixture.
B: Debris in radiator fins
106
If a fuel pump in an EFI system primes when the key is initially turned on but will not start when the engine is cranked, which of the following is the most likely cause?
a. PCM failure.
b. Fuel pump relay
c. Oil pressure switch.
d. Crankshaft position sensor.
d. Crankshaft position sensor.
107
A port fuel injection engine has low fuel pressure measured at the fuel rail. Which of the following should be done first?
a. Replace the fuel filter.
b. Replace the fuel pump.
c. Test dynamic pressure downstream from the fuel filter.
d. Test dynamic pressure downstream from the fuel pump.
.
d. Test dynamic pressure downstream from the fuel pump
108
A throttle-body fueled engine with dual injectors has good sparks but no injector pulse on both injector circuits. Which of the following is the most likely cause?
a. Defective crank sensor.
b. Burned fuse.
c. TPS return signal measuring 0.66 V-
DC.
d. High resistance in the injector ground
circuit.
b. Burned fuse
109
When should a port fuel-injected vehicle have the highest fuel pressure?
a. Closed throttle.
b. 25% throttle.
c. 60% throttle.
d. 100% throttle
d. 100% throttle
110
On a misfiring gasoline fuel-injected vehicle with adequate spark, the affected cylinder’s fuel injector is not audible working, but has acceptable resistance. Which of the following is the likely cause?
a. Plugged injector inlet screen.
b. Shorted injector coil.
c. Low fuel pressure.
d. Seized armature.
d. Seized armature.
111
On a no return circuit type of fuel system, what helps to control the fuel pressure when the pressure regulator is located in the fuel tank?
a. BARO sensor
b. Engine Vacuum
c. MAP sensor.
d. Oxygen sensor
c: MAP sensor
112
When an automobile engine is run without a thermostat, which of the following conditions would be most likely to result?
a. Higher HC and CO emissions [Hydrocarbons, Carbon Monoxide]
b. Higher NOx emissions.
c. Engine overheat.
d. Poor acceleration.
a. Higher HC and CO emissions
113
A V6 engine with a zirconium dioxide-type oxygen sensor has 1 defective spark plug. Which of the following conditions would be the most likely to result?
a. High NOx emissions.
b. Underfuelling of all cylinders and
cooler engine operation.
c. Over-fueling of all cylinders and
overheating.
d. Shutdown of companion to deal with cylinder.
c. Over-fueling of all cylinders and overheating
114
A gasoline-fueled engine starts to ping as soon as it reaches operating temperature but runs well during the warm-up phase. Which of the following could account for the condition?
a. Octane rating of the fuel is low.
b. Octane rating of the fuel is high.
c. Advance ignition timing.
d. Retarded ignition timing.
a. Octane rating of the fuel is low.
115
Which of the following conditions would create an increase in fuel rail pressure in a sequential port, gasoline fuel-injection system?
a. Defective knock sensor
b. High altitude operation.
c. Vacuum drop-off.
d. Vacuum increase.
c. Vacuum drop-off.
116
Which of the following best describes what happens when the armature of a gasoline fuel injector is energized when the engine is running?
a. Accumulator opens.
b. Injector closes
c. Fuel is injected.
d. DTC is logged.
c. fuel is injected
117
A standard-type oxygen sensor outputs a voltage signal of 0.35 volts DC. Which of the following should be true?
a. Fueling is lean.
b. Fueling is stoichiometric.
c. Fueling is rich.
d. Oxygen sensor is defective.
a. Fueling is lean.
118
When performing an injector balance test on a sequential injection engine, what would be the most likely cause of an injector that has a lower-than-normal pressure drop when activated?
a. Open injector.
b. Shorted injector.
c. Plugged injector.
d. PCM injector-driver fault.
c. Plugged injector.
119
Which of the following is true of a typical sequential-port gasoline fuel injector?
a. Actuated by an AC voltage spike.
b. Ground side control by ECM
c. Power side controlled by ECM.
d. Opened by a spring when energized.
b. Ground side controlled by ECM
120
An OHC engine is different than most other engines in the fact that it:
A) has a camshaft located in the cylinder head.
B) has more moving parts.
C) consistently develops more torque.
D) will have less accuracy when timing valves.
A) has a camshaft located in the cylinder head.
121
When an engine with sequential port fuel injection is difficult to start after being shut down overnight, but otherwise performs well, which of the following would most likely account for this condition?
a. Leaking fuel rail.
b. Defective accumulator or fuel pump
check valve.
c. Inoperative fuel pump relay.
d. Worn out fuel pump vanes.
b. Defective accumulator or fuel pump
| check valve.
122
```
Which of the following should be done before removing a port-fuel injection injector?
a. Disconnect the PCM.
b. Disconnect the fuel pump harness.
c. Relieve fuel pressure.
d. Apply vacuum to the fuel pressure
regulator.
```
c. Relieve fuel pressure.
123
A V6 engine with zirconium dioxide-type oxygen sensor has 1 defective spark plug. Which of the following conditions would be most likely to result?
a. High NOx emissions.
b. Underfuelling of all cylinders and cooler
engine operation.
c. Overfuelling of all cylinders and
overheating.
d. Shutdown of companion to dead cylinder.
c. Overfuelling of all cylinders and
| overheating.
124
Which of the following is true of a typical sequential-port gasoline fuel injector?
a. Actuated by an AC voltage spike.
b. Ground side controlled by ECM.
c. Power side controlled by ECM.
d. Opened by a spring when energized.
b. Ground side controlled by ECM.
125
Which of the following would be the likely cause of a "hard to start" complaint that only occurs when the engine is at operating temperature?
a. Retarded ignition timing.
b. Advance ignition timing.
c. Shorted crankshaft position sensor.
d. Fuel contamination of engine oil.
b. Advance ignition timing.
Advance ignition timing is a common cause of a warm engine " hard to start" complaint.
126
A standard oxygen sensor is producing an average reading of 450mV on an engine that is at operating temperature and assumed to be in closed loop mode. What should happen to the voltage reading if you created a vacuum leak by disconnecting a small vacuum hose?
a. Nothing.
b. Voltage reading would go up
c. Voltage reading would go down.
d. Engine stalls.
c. Voltage reading would go down.
127
Which of the following input sensors should produce nearly identical readings on a vehicle at the moment of start up after being shut down for 12 hours?
a. MAF and MAP
b. ECT and IAT.
c. DTC and TPS.
d. VSS and CKP.
b. ECT and IAT.
128
How many pins are in an OBD II-compliant data link connector?
a. 2.
b. 8.
c. 16.
d. 32.
c. 16.
129
What is the minimum number of data freeze-frames captured by an OBD II-compliant vehicle after a DTC is set?
a. No minimum.
b. 1.
c. 2.
d. 8
b. 1.
130
```
Which vehicle system do all OBD II Type A and B diagnostic trouble codes relate to?
a. Engine.
b. Exhaust.
c. Emissions.
d,
```
c. Emissions.
There are two categories of DTC's that apply to OBDII. They are listed below with Type A being the more severe.
```
Type A
1. Emissions related.
2. Requests illumination of the MIL after
one failed driving cycle.
3. Stores a freeze frame DTC after one
failed driving cycle.
```
```
Type B
1. Emissions related.
2. Sets a Pending Trouble Code after one
failed driving cycle.
3. Clears a Pending Trouble Code after
one successful driving cycle.
4. Turns on the MIL after two consecutive
failed driving cycles.
5. Stores a freeze frame after two
consecutive failed driving cycles.
```
131
How is a warm-up cycle defined for purposes of OBD II code log clearance?
a. 3 consecutive 3 on 3 off cycles.
b. coolant temperature increase of at least 22 degrees C (71.6 degrees F)
c. coolant temperature exceeds 70
degrees C (158 degrees F)
d. coolant temperature exceeds 70 degrees C after an increase of at least 22 degrees C..
coolant temperature exceeds 70 degrees C after an increase of at least 22 degrees C
132
If you unplug a coolant temperature sensor terminal from the coolant sensor on a warm engine, which of the following would result?
a. The engine will automatically shut down.
b. Coolant temperature is displayed on a scan tool at the highest possible reading.
c. A DTC is indicating open.
d. A DTC is set indicating voltage high.
c. A DTC is indicating open.
133
```
If you unplug a coolant temperature sensor terminal from the coolant sensor on a warm engine, which of the following would result?
a. The engine will automatically shut
down.
b. Coolant temperature is displayed on a
scan tool at the highest possible
reading.
c. A DTC is indicating open.
d. A DTC is set indicating voltage high.
```
c. A DTC is indicating open.
134
Which of the following conditions would be more likely to account for a low output voltage from a standard O2 sensor sensor located upstream from the catalytic convertor?
a. Plugged catalytic convertor
b. Restricted exhaust system
c. Failed air injection circuit.
d. cracked exhaust manifold
d. cracked exhaust manifold
135
Which of the following running conditions would be more likely to require a richer than stoichiometric air-fuel mixture?
a. Normal cruising.
b. Light load operation.
c. Deceleration.
d. Idling.
d. Idling.
Generally, a leaner mixture is required for normal cruising and light load operation .
A richer than stoichiometric mixture is required for idling, heavy load and hard acceleration.
136
```
An engine fueled with 89 octane gas pings especially when accelerated. The fuel is specified as a 10% ethanol cut, which of the following would be more likely to remedy
the condition?
a. Advance the base ignition timing.
b. Change to a higher octane-rated fuel.
c. Chance to a lower octane-rated fuel.
d. Change to an ethanol-free gasoline.
```
b. Change to a higher octane-rated fuel.
137
What should result when the vacuum hose on the fuel regulator on a port-injected fuel injection system is removed?
a. Fuel rail pressure decreases.
b. Fuel rail pressure increases
c. Fuel rail pressure unaffected.
d. Engine stalls.
b. Fuel rail pressure increases
138
While performing a noid light test to diagnose a fuel injector problem, the noid light illuminates but appears to be dim. What conditions is indicated?
a. High resistance inn the fuel injector coil.
b. Short circuit in fuel injector harness.
c. Short circuit in fuel injector coil.
d. High resistance in the fuel injector wiring
or connector.
d. High resistance in the fuel injector wiring
| or connector.
139
A gasoline fuel pump produces a whine from the fuel tank when it operates. Which of the following should be performed before making the decision to replace the pump?
a. Replace the fuel filter.
b. Replace the fuel regulator.
c. Replace the fuel tank.
d. Replace the fuel injectors.
a. Replace the fuel filter.
140
You have electrically tested a set of injectors on a V6 engine with around 200,000kms on the odometer and found 3 to be defective to the point of requiring replacement. Which of the following would be the correct procedure?
a. Keep testing the 3 good injectors to see
if you can make them fail.
b. Replace the solenoids on the 3 defective injectors.
c. Recommend that a set of 6 new injectors
be installed.
d. Switch the location of the 3 good and
the 3 defective injectors.
c. Recommend that a set of 6 new injectors
| be installed.
141
When a vacuum hose is removed from a vacuum-modulated fuel pressure regulator, a small quantity of fuel drips from the hose. Which of the following is the most likely cause?
a. Excessively high rail pressure.
b. Leak in the fuel rail return circuit.
c. Leak in the regulator diaphragm.
d. Restriction in fuel rail inlet.
c. Leak in the regulator diaphragm.
142
When scoping a pulse width-actuated injector, where should the inductive kick (spike) occur on the graph?
a. At the end of the pulse width profile.
b. At the center of the pulse width profile.
c. At the beginning of the pulse width
profile.
d. Profile should be entirely "square" if the
injector is good.
a. At the end of the pulse width profile.
143
You are scoping one of a set of injectors in a port-injected fuel system and observe the inductive kick displayed in the graphic to gradually reduce in length as the engine warms to operating temperature. What is the likely cause?
a. Short in the injector coil.
b. Open in the injector coil.
c. High resistance in the injector coil.
d. Injector pulse width is shortened as the engine reaches operating temperature.
d. Injector pulse width is shortened as the engine reaches operating temperature.
144
If the oxidizing stage of a catalytic converter on a gasoline engine is functioning properly, which of the following should be true regarding exhaust gas temperatures once the engine is at operating temperature?
a. Converter-in should be 15% warmer than
converter-out temperature.
b. Converter-in and out temperatures
should be equal.
c. Converter-out should be 15% warmer
than converter-in temperature.
d. Converter should be cool enough to be
touch by hand.
c. Converter-out should be 15% warmer
| than converter-in temperature.
145
Which type of ignition system eliminates spark plug wires?
a. COP (coil on plug)
b. DIS.
c. Direct fire system.
d. Contact point systems.
a. COP (coil on plug)
- coil on plug ignition system , each spark plug is ignited by its own coil. that means PCM can control the spark and spark timing.
DIS - distributorless ignition system.
146
Which of the following must be true of the shield used on an optical ignition sensor?
a. It must be airtight.
b. It must be periodically replaced.
c. It mush be light proof.
d. It must be lubricated with engine oil
prior to installation.
c. It mush be light proof.
Optical trigger uses a light emitting diode and a photo receptor.
147
When troubleshooting a distributorless ignition system, you identify a defective high-tension wire. Which of the following should be replaced along with the wire?
a. Spark plug.
b. Coil.
c. Ballast resistor.
d. Distributor pick-up coil.
b. Coil.
148
What switches primary circuit current in the ignition module in a typical electronic ignition circuit?
a. Transistor.
b. Hall-effect switch.
c. Optical switch.
d. Electro-mechanical switch.
a. Transistor.
149
When platinum spark plugs are to be reused, which of the following is correct procedure?
a. Regap to specification.
b. Coat threads lightly with anti-seize
compound and do not attempt to regap.
c. Apply 10 more than original specified
torque.
d. Glass bead blast the electrodes.
b. Coat threads lightly with anti-seize
| compound and do not attempt to regap.
150
When scoping a good pair of plugs on a waste spark ignition system, what should distinguish the power spark from the waste spark on the oscilloscope pattern?
a. Firing line is higher on the power plug.
b. Firing line is lower on the power plug.
c. Intermediate oscillations diminish more
rapidly on waste plug.
d. Both patterns should be nearly identical
through the cycle.
a. Firing line is higher on the power plug.
151
```
When you disconnect a high-tension wire on a running engine while troubleshooting an ignition problem, what mush you do?
a. Prevent the high-tension wire from
contacting ground.
b. Disconnect the ignition module.
c. Ground the spark plug with a jumper
wire.
d. Ground the high-tension wire.
```
d. Ground the high-tension wire.
