ASE A8 ENGINE PERFORMANCE STUDY GUIDE 2025/26 QUESTIONS WITH PASSED
SOLUTIONS.
A hesitation on acceleration can be caused by? - (ANSWER)A faulty Throttle position sensor
A leak in the vacuum hose to a MAP sensor may cause? - (ANSWER)A higher-than-normal reading from
the sensor and can cause hesitation during acceleration
Tools that can be used to diagnose emission faults without a DTC. - (ANSWER)Power graphing multi
meter, labscopes, and graghing scan tools
Computer, sensor power feeds, grounds, and signal wires can be tested with a? - (ANSWER)DMM
Sensor and actuator waveform analysis can be performed with? - (ANSWER)Digital Storage Oscilloscopes
Fuel injectors, O2 Sensors are tested most effectively with? - (ANSWER)Waveform analysis
What issues may a stuck open PCV valve cause on a carburetor engine? - (ANSWER)Excessive air flow
through valves which can cause a lean air/fuel ration and possible rough idle, or stalling of engine
What issues may a stuck open PCV valve cause on a fuel injected engine? - (ANSWER)High idle speed
complaint
Oil accumulation and crankcase blow-by gases may be found in the air cleaner housing due to? -
(ANSWER)Worn piston rings and cylinders
What tester may be used to test for excessive engine blow-by? - (ANSWER)Flow meter style tester
What must be visually inspected on a PCV valve system? - (ANSWER)Inspect the cap, tubes, and hoses
for kinks, cuts or other damage
What must be confirmed in order to replace the PCV valve? - (ANSWER)Shake the valve next to your ear
and listen for valve rattle. If no rattle is heard, replacement is needed.
, ASE A8 ENGINE PERFORMANCE STUDY GUIDE 2025/26 QUESTIONS WITH PASSED
SOLUTIONS.
Proper operation of EGR valve - (ANSWER)The valve should open once the engine is warm and run
above idle or under road load conditions
What symptoms may you see if EGR valve remains open at idle and low engine speed? -
(ANSWER)Rough idling along with stalling can occur and engine surging may occur during low speed
driving
What symptoms may you see if the EGR valve is stuck open? - (ANSWER)Valve will create a density
misfire condition in which the air/fuel mixture is diluted with exhaust gases causing a misfire. This will
also increase Hydrocarbon emissions and raise oxygen levels
What symptoms may you see if an EGR valve is stuck closed? - (ANSWER)Engine detonation can occur
and an increase in oxides of nitrogen emissions.
What will happen if exhaust gases are introduced into the engine during acceleration and cruise
conditions? - (ANSWER)The inert exhaust gas helps reduce peak cylinder combustion temps below
2500'f
If the EGR valve does not open: - (ANSWER)Combustion chamber temps will rise and NOx production
will increase beyond what the catalytic converter can control
What three reasons may a EGR code be set? - (ANSWER)A control circuit fault, a no or low flow
condition, or an excessive flow or flow when not commanded condition
What is the first step in diagnosis for any EGR System? - (ANSWER)Check all of the system's vacuum and
electrical connectors
Proper testing of a vacuum operated EGR valve: - (ANSWER)A vacuum pump should be used to apply
vacuum to the valve to test the diaphragm and see that the valve opens
What component is most often the EGR's problem? - (ANSWER)EVR (Engine Vacuum regulator)
What testing equipment can be used on an EVR? - (ANSWER)Checked with a scan tool or an ohmmeter
SOLUTIONS.
A hesitation on acceleration can be caused by? - (ANSWER)A faulty Throttle position sensor
A leak in the vacuum hose to a MAP sensor may cause? - (ANSWER)A higher-than-normal reading from
the sensor and can cause hesitation during acceleration
Tools that can be used to diagnose emission faults without a DTC. - (ANSWER)Power graphing multi
meter, labscopes, and graghing scan tools
Computer, sensor power feeds, grounds, and signal wires can be tested with a? - (ANSWER)DMM
Sensor and actuator waveform analysis can be performed with? - (ANSWER)Digital Storage Oscilloscopes
Fuel injectors, O2 Sensors are tested most effectively with? - (ANSWER)Waveform analysis
What issues may a stuck open PCV valve cause on a carburetor engine? - (ANSWER)Excessive air flow
through valves which can cause a lean air/fuel ration and possible rough idle, or stalling of engine
What issues may a stuck open PCV valve cause on a fuel injected engine? - (ANSWER)High idle speed
complaint
Oil accumulation and crankcase blow-by gases may be found in the air cleaner housing due to? -
(ANSWER)Worn piston rings and cylinders
What tester may be used to test for excessive engine blow-by? - (ANSWER)Flow meter style tester
What must be visually inspected on a PCV valve system? - (ANSWER)Inspect the cap, tubes, and hoses
for kinks, cuts or other damage
What must be confirmed in order to replace the PCV valve? - (ANSWER)Shake the valve next to your ear
and listen for valve rattle. If no rattle is heard, replacement is needed.
, ASE A8 ENGINE PERFORMANCE STUDY GUIDE 2025/26 QUESTIONS WITH PASSED
SOLUTIONS.
Proper operation of EGR valve - (ANSWER)The valve should open once the engine is warm and run
above idle or under road load conditions
What symptoms may you see if EGR valve remains open at idle and low engine speed? -
(ANSWER)Rough idling along with stalling can occur and engine surging may occur during low speed
driving
What symptoms may you see if the EGR valve is stuck open? - (ANSWER)Valve will create a density
misfire condition in which the air/fuel mixture is diluted with exhaust gases causing a misfire. This will
also increase Hydrocarbon emissions and raise oxygen levels
What symptoms may you see if an EGR valve is stuck closed? - (ANSWER)Engine detonation can occur
and an increase in oxides of nitrogen emissions.
What will happen if exhaust gases are introduced into the engine during acceleration and cruise
conditions? - (ANSWER)The inert exhaust gas helps reduce peak cylinder combustion temps below
2500'f
If the EGR valve does not open: - (ANSWER)Combustion chamber temps will rise and NOx production
will increase beyond what the catalytic converter can control
What three reasons may a EGR code be set? - (ANSWER)A control circuit fault, a no or low flow
condition, or an excessive flow or flow when not commanded condition
What is the first step in diagnosis for any EGR System? - (ANSWER)Check all of the system's vacuum and
electrical connectors
Proper testing of a vacuum operated EGR valve: - (ANSWER)A vacuum pump should be used to apply
vacuum to the valve to test the diaphragm and see that the valve opens
What component is most often the EGR's problem? - (ANSWER)EVR (Engine Vacuum regulator)
What testing equipment can be used on an EVR? - (ANSWER)Checked with a scan tool or an ohmmeter
