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About This Quiz
Are you a real whiz when it comes to engine repairs? Could you walk into a professional shop and start diagnosing and fixing engine trouble without any problems? Not everyone's cut out for that kind of work, which has become increasingly technical. You might be an accomplished shade tree mechanic, but today's engines demand far more knowledge!
Modern engines are much more complex than what was powering vehicles 50 years ago. Old hot rodders would gap their spark plugs with a broken butter knife, and that was considered technical back in the day. Today, car engines are controlled by computers, which work with a whole array of sensors to measure everything from air intake temperature to the amount of oxygen in the exhaust gases. This data helps the ECU change the air/fuel mixture for greater efficiency. As a result, cars have become more powerful, consume less fuel, and even run with fewer problems. But all this complexity means when there is something to be fixed on a modern engine, mechanics need far more knowledge than ever.Â
To help ensure mechanics are repairing engines correctly, ASE provides an engine repair section in its certification testing. Could you pass the test? Find out now by taking this quiz!Â
What makes a knocking sound on the side of the engine, but it becomes softer as the engine warms up?
piston slap
The dead giveaway that it's piston slap is the fact that it's loudest when the engine is cold.
wrist pin
detonation
cam bearings
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Where do problems with fuel propagation show up?
in the battery
in the fuel pump
in the spark line
The spark line is the voltage required to maintain a spark, with any problems related to burning fuel manifesting in coil voltage and total primary circuit resistance, which are related to spark line.
in the O2 sensor
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If an engine with an electronic ignition and no distributor won't start, plus you find a DTC of the crankshaft position sensor, what's the most likely cause of the problem?
bad O2 sensor
defective cam position sensor
The engine position sensor ground has gone bad.
In this situation, it's a bad engine position sensor ground that will trigger this code, PO335.
blown coil
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When doing an engine compression test, you'd disable the ignition system and fuel injection on an engine for all but which of the following reasons?
It avoids fire risks.
It avoids accurate readings.
The whole reason for disabling these systems is to prevent safety issues, not to get a more accurate reading.
It avoids damages to the ignition system.
It keeps fuel from being injected into the cylinders.
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If an engine will crank but it doesn't start, what should you check on first?
battery
starter
ignition circuit
The ignition circuit is always the first item on a no-start symptoms flow chart, and for good reason. That doesn't mean you'll find a fault there, but it's the best place to start.
ground circuit
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If you hear a flapping sound near the front of the engine compartment, which of the following could be the source?
a loose radiator
timing belt tension is loose
One sign of a loose timing belt is a flapping sound, which will usually come from the front part of the engine compartment, so check for belt tension.
timing belt overly tight
drive belt overly tight
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Which of the following could trigger a diagnostic trouble code of a small leak detected in the EVAP canister system?
bad MAF
defective gas cap
A broken or even incorrect gas cap can trigger this code, while a defective or leaking vent solenoid is another possibility.
corroded air temperature sensor
corrupted O2 sensor
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Which trip will the PCM or ECM most likely turn on the malfunction indicator lamp if the OBD II system reads a disconnected spark plug as a misfire that could lead to catalyst damage?
first
This is most likely on the first trip, but there's always a possibility it could happen on the others.
second
third
fourth
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If you find with an injector power balance test that one injector isn't operating but it's still receiving the proper power supply, what's the next step?
continuity check between the injector and PCM
Except in rare cases, a continuity check between the injector and PCM is recommended, if the injector is getting the proper power.
voltage check at ignition power feed
continuity check between injector and fuse
voltage drop of injector ground
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Where should you always go to get service procedures for any vehicle?
online
With few exceptions, all OEM service information is available online, and it's updated, which you can't say about printed service information.
in the shop's extensive collection of manuals
at the local library
NAPPA
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Which of these problems would clue you into the fact the EGR valve on a car is closed?
spark knock
If the exhaust gas recirculation valve is always closed, the spark knock is one symptom. The other three options actually indicate an EGR valve that's always open.
engine surge
rough idle
stumbling
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If the electronic controlled throttle return spring on a car malfunctions, what's a possible result?
no start
fluctuating idling RPM
lower power
When the return spring goes out, the circuit automatically triggers a defensive measure where the engine RPM won't go above 2,000, resulting in the lower power output.
detonation
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When installing a valve spring, what's the correct orientation?
open coil end against the cylinder head
closed coil end against the cylinder head
To avoid performance problems, you should always place the closed coil end of the spring against the cylinder head.
counterclockwise
clockwise
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Before you reprogram an engine control module, what do you need to do?
measure tire tread depth
figure out what software you need to install
You can't charge into a reprogramming situation if you don't know what you need to use for the reprogramming, so this is the first step.
recalibrate the scan tool
watch a YouTube guide
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When doing a power balance test, what do you want to note before and during the test for each cylinder?
ignition timing
RPM
Both before and during the test, as well as for each cylinder, you need to record engine RPM to get accurate results for the test.
fuel consumption
exhaust output
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What kind of load is placed on a vehicle for the Acceleration Simulation Mode?
double weight
single weight
For the Acceleration Simulation Mode (ASM) you need to put the vehicle on a dynamometer and place a single weight load on it, just like the EPA certification testing.
triple weight
cascading weight
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Why would an engine run rough after the battery was disconnected for a while?
PROM failure
EPROM failure
The learned value was lost from ROM.
The learned value was lost from RAM.
With battery power gone, in some cars the data on the proper air/fuel mix for the cylinders can be lost, leaving the system to use the factory presets, which are designed for new engines.
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What emissions will an engine misfire increase?
CO and TC
O2 and HO
CO and SA
CO and HC
All misfires not only increase CO and HC emissions, but they also produce a specific diagnostic trouble code.
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What do you need when looking for service info for a specific vehicle?
make, model and year
With few exceptions, all data services online require you to have the make, model and year of the vehicle.
VIN
vehicle build date
model year
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What two problems can a crushed PCV hose cause for an engine?
oil leaking and engine surge
oil leaking and trouble idling
For most engines, the PCV supplies some of the idle air, plus it creates positive crankcase pressure if it's restricted at all, which would lead to an oil leak developing.
stumbling and a rich mixture
a lean mixture and oil leaking
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Which of the following isn't something you must always do when adjusting valve lash on engines with overhead camshaft heads?
measure clearance between the camshaft and rocker or follower
allow the engine to completely cool first
Whether the engine needs to be completely cooled or not before doing this job really depends on OEM procedure, so you'll need to look it up.
make adjustments with shims
place the rocker or follower on the camshaft base circle when measuring
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Which of the following would be the result of a closed EGR valve?
spark knock
If the EGR or exhaust gas recirculation valve is always open, spark knock occurs.
engine surge
rough idle
stalling
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What does mixing coolant with distilled water do to the cooling system?
It accelerates corrosion.
It keeps the engine cooler.
It doesn't freeze as easily.
nothing
Distilled water doesn't do anything to the cooling system, so using tap water is perfectly acceptable.
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While cranking an engine, if a 12-volt test light, which is connected to the negative primary coil terminal for an electronic distributor ignition, flutters, while a spark tester doesn't fire while connected to the coil secondary wire, what's likely the cause?
bad spark plug
defective pickup coil
defective ignition coil
If the test light is fluttering, that means the ignition coil triggering device works, while no spark means the coil is failing.
bad ignition module
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Which of the following could cause the sensors on an electronically controlled EGR valve to melt?
a lean mix
excessive back pressure
A partial clog in the exhaust system can create too much back pressure, which would melt the plastic sensors.
incorrect spark plugs
incorrect gas octane
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When a cylinder head has been machined, what must you do with the valve train?
shim the head
lengthen the pushrods
increase valve spring tension
grind the valve stems
Thanks to the machining, the distance between the rocker and pushrod reduces, making it necessary to grind the valve stems as a way to compensate.
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When dealing with a drivetrain problem using a diagnostic strategy, what do you usually do last?
verify the repair
By verifying the repair, you can ensure that everything was done correctly, so the customer doesn't return for the same issue shortly.
look up the vehicle's history
verify customer concerns
perform service checks
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What test could you use to tell if an engine has a broken valve spring?
cranking vacuum
scope firing lines
running vacuum
Through a running vacuum test, a broken or even a weak valve spring will be revealed, thanks to fluctuating readings at different engine speeds.
cranking compression
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Under normal operation, what should happen as you use a scan tool to check fuel injector balance as part of a service manual procedure?
coolant temperature drops
coolant temperature rises
engine RPM rises when each injector is shut down
engine RPM drops when each injector is shut down
If there's a fault in a cylinder, when the corresponding injector is turned off, engine RPM should slow.
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What effect on engine performance would a clogged PCV valve have?
surging
stumbling
rough idling
The PCV system actually provides some of the air used by the engine when idling, so having some of that airflow cut off would possibly lead to a rough idle.
spark knock
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What causes a thumping or knocking on the side of the engine block, and it gets louder as the engine heats up?
rod bearing
This noise is from the rod bearing, with the increase of the noise as temperatures increase being the dead giveaway.
piston slap
wrist pin
main bearing
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When diagnosing a vehicle with electronic fuel injection and a distributorless ignition that won't start, which of the following tools can be used?
spark plug gapper
digital multimeter
A digital multimeter or DMM can check for voltage on the powertrain control module, or you can check for spark at any of the spark plugs.
OBD II reader
emissions rod
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When you're going to diagnose an engine with a performance problem, what's the first step?
look up the service manual
take the vehicle on a road test
retrieve any diagnostic trouble codes
discuss concerns with the owner
Before you run any diagnostics, perform a road test, etc. you should speak to the vehicle owner and get a detailed account of what's going on.
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If an engine that won't start has no spark to the plugs, where should you connect a digital multimeter?
the ignition coil and a ground
You should connect the red lead on the digital multimeter to the negative terminal on the coil, then ground the black lead. As you crank the engine, the voltage should fluctuate.
the ignition coil and the battery
the battery and a ground
the ignition coil and the first ignition wire
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If you don't regularly change antifreeze, what can happen with the cooling system?
It seizes up.
corrosion builds up
All coolant contains a corrosion inhibitor, but it doesn't last forever. If the system isn't drained and new coolant put in, corrosion is inevitable.
All the hoses will burst.
It will only cool, not heat.
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