Engine Performance SOS/ASE
What are the key components in an EVAP system? - correct answer Fuel Tank, gas cap,
lines/hoses, and charcoal canister
Catalytic Converter: - correct answer Oxidizes NOx into CO and HC
When testing a connector what is an acceptable reading?
a.) 1V from ground side
b.) 1V from positive/reference side
c.) .5V from at each connector
d.) 1.5v from sensor harness - correct answer C
An oxygen sensor is reading 400mv, what would this indicate - correct answer lean condition
What increases NOx emissions? - correct answer High combustion temperatures
You have examined a set of spark plugs and found them to have a black crusty finish on them.
What does this indicate? - correct answer Rich air/fuel mixture
A vehicle comes in with poor performance, low power and a flashing check engine light. What
would this indicate? - correct answer Engine misfire
What is the function of the EGR valve? - correct answer to recirculate exhaust gases into the
intake
Emission control systems are installed on engines to reduce what 3 specific exhaust emissions? -
correct answer (HC) hydrocarbons, (CO) Carbon Monoxide, and Oxides of Nitrogen (NOx)
,Engine Performance SOS/ASE
You are monitoring the TPS/APP sensor voltage reading with slow steady acceleration should
read: - correct answer .50v at idle to 4.5 at WOT
If the voltage reading on one cylinder is not high enough, what is the most likely source of the
problem? - correct answer Bad spark plug
At WOT the PCM module reverts to: - correct answer Open loop, rich mixture
What are the 2 types of EVAP Leaks? - correct answer 0.020 small leak and 0.040 large leak
1.) All the following are pre-combustion emission controls except:
a.) Catalytic converter
b.) PCV system
c.) Timing control systems
d.) EGR systems - correct answer A
Tech A says that HCs result from unburned fuel and from incomplete combustion.
Tech B says that CO is formed with a mixture that is too rich.
Which Technician is correct? - correct answer Both
Port injection injects fuel: - correct answer Injects fuel behind the intake valve
(DI) Direct Injection: - correct answer Injects fuel directly into the combustion chamber (Diesels)
What do post-combustion control systems do? - correct answer Cleans up exhaust gases after
fuel has been burnt
, Engine Performance SOS/ASE
What does the downstream O2 sensor do? - correct answer monitors catalytic converter
efficiency
Why is idle speed increased during a cold start?
a.) To prevent misfires
b.) To warm up the catalyst
c.) To make it easier to drive away
d.) To heat up the hot wire in the MAF sensor - correct answer A
Which of the following does the PCM use to determine air flow?
a.) BARO
b.) ECT
c.) MAF
d.) HO2S - correct answer C
What does the PCM do to ignition timing during WOT?
a.) Advance
b.) Retard
c.) Overlap
d.) Set to base - correct answer A
In a DTC code what does "U" signify? - correct answer Communication code (Network)
OBD II monitors have specific criteria that must be met in order for them to run and complete.
What are they called?
a.) Type A faults
b.) Drive cycles
What are the key components in an EVAP system? - correct answer Fuel Tank, gas cap,
lines/hoses, and charcoal canister
Catalytic Converter: - correct answer Oxidizes NOx into CO and HC
When testing a connector what is an acceptable reading?
a.) 1V from ground side
b.) 1V from positive/reference side
c.) .5V from at each connector
d.) 1.5v from sensor harness - correct answer C
An oxygen sensor is reading 400mv, what would this indicate - correct answer lean condition
What increases NOx emissions? - correct answer High combustion temperatures
You have examined a set of spark plugs and found them to have a black crusty finish on them.
What does this indicate? - correct answer Rich air/fuel mixture
A vehicle comes in with poor performance, low power and a flashing check engine light. What
would this indicate? - correct answer Engine misfire
What is the function of the EGR valve? - correct answer to recirculate exhaust gases into the
intake
Emission control systems are installed on engines to reduce what 3 specific exhaust emissions? -
correct answer (HC) hydrocarbons, (CO) Carbon Monoxide, and Oxides of Nitrogen (NOx)
,Engine Performance SOS/ASE
You are monitoring the TPS/APP sensor voltage reading with slow steady acceleration should
read: - correct answer .50v at idle to 4.5 at WOT
If the voltage reading on one cylinder is not high enough, what is the most likely source of the
problem? - correct answer Bad spark plug
At WOT the PCM module reverts to: - correct answer Open loop, rich mixture
What are the 2 types of EVAP Leaks? - correct answer 0.020 small leak and 0.040 large leak
1.) All the following are pre-combustion emission controls except:
a.) Catalytic converter
b.) PCV system
c.) Timing control systems
d.) EGR systems - correct answer A
Tech A says that HCs result from unburned fuel and from incomplete combustion.
Tech B says that CO is formed with a mixture that is too rich.
Which Technician is correct? - correct answer Both
Port injection injects fuel: - correct answer Injects fuel behind the intake valve
(DI) Direct Injection: - correct answer Injects fuel directly into the combustion chamber (Diesels)
What do post-combustion control systems do? - correct answer Cleans up exhaust gases after
fuel has been burnt
, Engine Performance SOS/ASE
What does the downstream O2 sensor do? - correct answer monitors catalytic converter
efficiency
Why is idle speed increased during a cold start?
a.) To prevent misfires
b.) To warm up the catalyst
c.) To make it easier to drive away
d.) To heat up the hot wire in the MAF sensor - correct answer A
Which of the following does the PCM use to determine air flow?
a.) BARO
b.) ECT
c.) MAF
d.) HO2S - correct answer C
What does the PCM do to ignition timing during WOT?
a.) Advance
b.) Retard
c.) Overlap
d.) Set to base - correct answer A
In a DTC code what does "U" signify? - correct answer Communication code (Network)
OBD II monitors have specific criteria that must be met in order for them to run and complete.
What are they called?
a.) Type A faults
b.) Drive cycles
