chapter 83
inadequate purge flow rate will trigger which DTC
PO440
small leak will set a
PO442
if you over fill your gas tank you could saturate your charcoal canister with liquid fuel which would cause
an overly rich fuel mixture when the canister purge valve is opened during normal operation
which valve is normally closed
canister purge valve
the EVAP system includes
charcoal canister hoses valves
the canister purge valve, also called the canister purge (CANP) solenoid, is normally __________ and is __________________________ by the PCM during purging
closed pulsed open
under normal conditions most engine control systems permit purging only during
closed loop operation at cruising speeds
what is vapor purging
during engine operation stored vapors are drawn from the canister into the engine through a hose connected to the throttle body or air cleaner
many vehicles use a vacuum operated leak detection pump (LDP) as part of the
evaporative control system diagnosis equipment
enhanced exhaust emissions (I/M-240) testing tests the
evaporative emissions system
black cap is what test port
fuel rail pressure
manifold vacuum is also applied to the pressure control valve that when it opens
fumes from the fuel tank are drawn into the charcoal canister
EVAP test port is what color cap
green
all of the following can increase the pressure in the evaporative emission control system except
inlet fuel to the fuel pump
when the computer turns on the canister purge solenoid valve what happens
manifold vacuum draws any stored vapors from the canister into the engine
the canister vent valve is a normally ______________ valve and is ____________ only when commanded by the PCM during testing of the system
open closed
what can be signes of a vacuum leak
poor fuel economy engine run rough
most EVAP fuel tank filler caps have a built in
pressure vacuum relief valve
I/M-240 testing uses what to test for a leak
pressurizes the entire fuel system to a level below 1 PSI (About 14 inch H20) the system is pressurized with nitrogen
during other engine operation conditions such as open loop mode, idle, deceleration, or WOT, the PCM
prevents canister purging
from the charcoal canister where do the vapors go
routed to the intake air flow to be burned
what method is the most efficient for EVAP leak testing
smoke machine testing
what are the 2 methods of testing for a EVAP leak
smoke machine testing nitrogen gad pressurization
the purpose of the EVAP system is to
trap and hold gasoline vapors
pressures can build inside the fuel system are usually measured in
units of inches of water
during a canister purge cycle if no __________ exists a code will be set for a ________________ solenoid
vacuum clogged
which EVAP valve is subject to rust and corrosion more than all of the others
vent valve
fuel evaporation rates
volatility
a charcoal canister can hold
1/3 of their own weight in fuel vapors
a Light will not come on until the evap has failed how many times
2
evaporative emission control systems operate on how low pressure measured in inches of water. one PSI equals to hoe many inches of water
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