Emission Controls Flashcards
A - the PCV valve flow is high at idle.
B - PCV valve flow is high at cruising speed on a vehicle with an 8 cylinder engine.
both incorrect
PCV valve flow is low at high vacuum (idle, cruising).
A - if the PCV valve rattled when shaken, then the PCV system is okay.
B - the PCV system vents excess pressure formed in the crank case from piston blowby.
A - incorrect. Doesn’t mean the PCV valve is functional.
B - correct.
A - oil found inside the air filter housing may be caused by excessive crankcase blowby.
B - a plugged PCV valve will cause excessive crankcase pressure.
both correct
A - an EGR valve stuck closed will cause detonation.
B - an EGR valve stuck closed will cause high NOx emissions.
both correct
All of the following can cause spark knock except: A - stuck open EGR valve. B - stuck closed EGR valve. C - broken vacuum hose going to the EGR. D - defective cooling system thermostat.
A - a stuck open EGR valve will keep the combustion chamber cold, preventing spark knock.
A - the EGR system is used to raise combustion chamber temperature.
B - EGR systems that use an EGR valve position sensor should read about 0.7V with the EGR valve at full open.
A - incorrect
B - incorrect. 5.0V at full open.
A - an anti-backfire valve should be used to prevent backfiring during deceleration on pump driven air injection systems.
B - to prevent exhaust gases from back flowing into the air injection control valves or pump, check valves can be used in the exhaust manifold and converter feed pipes.
both correct
The anti-backfire valve (diverter valve) helps prevent backfire in the exhaust on deceleration. To protect the secondary air system from the hot air of the exhaust, one way check valves are used.
A - a secondary air injection system directs output from the air pump to the exhaust manifold during engine warmup and switches air to the catalytic converter during closed loop operation.
B - air injection will have little or no effect on tailpipe carbon dioxide readings.
A - correct.
B - correct. CO2 is a combustion gas.
A - the air pump should pump the air into the exhaust manifold when in open loop.
B - the air should be pumped into the catalytic converter once the vehicle enters closed loop.
both correct
A - a leaking gas cap gasket can cause an evaporative emissions failure.
B - some evaporative emissions canisters have a replaceable filter.
both correct
On older vehicles the vapor canisters use a replaceable fiberglass EVAP filter.
