A8 Engine Performance practice test
Questions and Answers (100% Pass)
D. The PCV valve should rattle when shaken back and forth.
When the thumb is placed over the end of the PCV valve with the engine idling, the
plunger should snap back.
A water manometer can be used to check the crankcase for vacuum at idle.
There is no blowby test that is performed on the PCV system. - ✔️✔️All of the
following are tests performed on the PCV system EXCEPT:
A. The rattle test
B. The snap- back test
C. Crankcase vacuum test
D. Blowby test
C. Faulty secondary ignition components are common causes of ignition module
failure.
Some modules require the use of dielectric grease to aid in dissipating heat.
A fouled spark plug would cause an engine miss, but would not cause the ignition
module to fail.
Loose module mounting screws will cause the module to fail prematurely. -
✔️✔️Which of the following is the LEAST LIKELY cause of ignition module failure?
A. A partially restricted fuel return hose would cause the fuel pressure to be higher
than it should. This would cause poor fuel economy without affecting drivability.
A stuck open fuel regulator would lower fuel pressure, possibly causing a no-start,
but would not cause a fuel economy complaint. - ✔️✔️A sequential fuel- injected
vehicle has poor fuel economy, yet starts and runs fine. Technician A says the fuel
return line may be partially restricted. Technician B says the fuel pressure
regulator may be stuck open. Who is correct?
A. Tech A
B. Tech B
C. Both technicians
D. Neither technician
A. The EGR system is used to lower combustion chamber temperature . If the EGR
system does not operate, then the engine will operate too hot, causing spark knock
and elevated oxides of nitrogen (NOx) reading.
An inoperative EGR system will raise combustion chamber temperatures and cause
the engine to run hotter. - ✔️✔️Technician A says if the passages in the exhaust gas
recirculation (EGR) system get plugged up with carbon, then the engine could spark
knock. Technician B says if the EGR passages get plugged up, then the engine will
not run hot enough for complete combustion. Who is correct?
C. Both. When the power transistor in the ignition control module opens the
primary ignition circuit, the build-up magnetic field in the coil collapses. This
produces the secondary voltage to jump the gap at the spark plug. The voltage that
the coil produces can be broken down into three different types: "required voltage"
(the voltage required to jump the gap at the spark plug), "available voltage" (the
voltage available to jump the gap at the spark plug), and the "reserve voltage" (the
voltage in reserve after the spark plug fires). As the engine accelerates, the required
voltage goes up. If there is not enough voltage in reserve, then the engine will miss.
- ✔️✔️Technician A says a coil with weak reserve voltage could cause a miss under
acceleration. Technician B says the ignition coil only produces enough secondary
voltage to jump the spark plug gap. Who is correct?
A. Tech A
B. Tech B
C. Both technicians
D. Neither technician
D. Simple test should be performed, but not until the problem is verified.
The DTCs will eventually be retrieved, but not before verifying the complaint.
Once any trouble codes are retrieved, a technical service bulletin search should be
performed, but not before the complaint is verified.
The very first step to doing any diagnostic procedure is to verify the customer
complaint. - ✔️✔️Which of the following is the very first step a technician should take
when performing a diagnostic procedure?
A. Perform simple tests
B. Retrieve diagnostic trouble codes (DTCs)
C. Check for technical service bulletins (TSBs)
3
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