1 EVAP System testing using a Smoke Machine. 2 Purpose A smoke machine is used to identify leaks in systems that hold and transfer air and vapor.

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EVAP System testing using a

Smoke Machine

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Purpose

• A smoke machine is used to identify leaks in systems that hold and transfer air and vapor.

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Usage

• The primary function of the smoke machine is to test the integrity of the Evaporative Control System

• The smoke machine can also be used to detect:– Intake air system leaks– Exhaust system leaks– Cabin air/window seal leaks

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Other Test Applications

• Air cleaner assembly • Air ducts • Air valves • Component testing,

prior to assembly• Diaphragms • EGR valve • Exhaust manifolds

cracks• Fuel tank pressure

sensor • Intercoolers • Intake gaskets

• Injector o-rings • Loose clamps • Map sensors • Mass air flow meter • Oil leaks • PCV valve and hoses • Throttle body shaft • Turbochargers • Vacuum hoses • Vacuum switches

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Visible smoke pinpoints the leak source

• A leak in the vapor recovery system can be easily identified by the presence of smoke at the gas cap

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Smoke machine components

12 volt power

cables

Smoke outlet hose

Exhaust pipe cone adapter

PlugsUV glasses

Schrader valve removal tool

Wireless remote

Vacuum pump adapter

EVAP test port adapter

UV light source

Smoke dispersal adapter

Smoke oil

Large tailpipe plug

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Smoke oil

• The smoke machine generates smoke by passing mineral oil over a red hot electric heating coil

• The oil contains a chemical that glows bright yellow when exposed to Ultra Violet [UV] light

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Ultraviolet Light source

• Condensed smoke oil will glow green/yellow when exposed to UV light

• An LED type UV flashlight is used to pinpoint the source of leaks

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Never look directly into the UV light

• Yellow UV safety glasses should be worn whenever working with UV light sources

• Exposure to UV light can cause permanent damage to the retinas of your eyes

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Condensed smoke oil

• A small amount of smoke vapor will condense around the places that the smoke leaks out of. This liquefied smoke will glow

• Smoke vapor will generally not glow when exposed to UV Light

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Check the oil supply

• A dipstick is attached to the smoke machine’s oil filler cap

• Unscrew the dipstick and observe the level of oil using the UV light to illuminate the dipstick

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Checking the oil

• Smoke oil is a clear liquid so it is difficult to see the level on the dipstick without the aid of UV light

Full Mark

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Adding oil

• If the oil level is low add a few ounces of oil – do not overfill

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Connect to the battery

• The smoke machine is powered by the vehicles battery via the 12 volt power leads at the back of the machine

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Hanging the smoke machine

• When the smoke machine will be used near the engine the machine can be hung from the hood latch

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Air Line coupler

• The correct type of coupler needs to be installed to connect the smoke machine to the shop’s compressed air hoses

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Shop air fitting

• Compressed air from the shop’s air compressor is used to push the smoke through the system being tested

• The correct air coupler fitting needs to be attached to the smoke machine

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Vapor hose

• The vapor hose is used to inject smoke into the system being tested

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Cone adapters• Rubber cones allow the vapor line to

connect and seal to a variety of different size and shaped openings

• The large cone adapter here is used to connect the vapor hose to the exhaust pipe

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Plugs

• Plugs may be needed to seal opening where components have been removed or where a small amount of leakage is expected

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Air Diffuser

• To find air leaks around windows and doors an air diffuser is used to spread out the smoke

• The vehicle’s HVAC fan is set to high speed while smoke is blown over the edges of the windows and doors

• Any disturbance in the smoke may indicate an air leak

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Adapter for EVAP test port

• Most late model cars have an EVAP system test port that uses an ACME thread [similar to the fitting on tank of R134a refrigerant.

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EVAP test port

• The cap is normally a light green color• The port is normally located under the hood but

is occasionally found underneath the car

• The EVAP test port is located on the vapor line between the purge solenoid and gas tank

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Vacuum pump port

• The auxiliary output port can be used to connect a hand held vacuum pump to the smoke machine

• Some EVAP systems use electro mechanical vacuum pump located inside the fuel tank to monitor EVAP system integrity

• A source of vacuum is needed to test the operation of the sensors and pump

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Vacuum Pump

• During the test a small amount vacuum is applied using a hand held vacuum pump

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Screen Display

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Function select buttons

• There are 3 membrane switches on the right side of the panel– The display select button changes

the units of measurement displayed by the 3 digit LCD matrix

– The orifice select button changes the size of the flow restriction inside the smoke machine

– The start button starts a 5 minute leak down test and toggles the machine between full flow and pulsed flow

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Display Indicator lights

• When illuminated an ‘Orifice Leak Size’ of .040”, .020” or .010” will be indicated on the LED display

• When the ‘Flow L/M’ is illuminated the LED displays the smoke flow rate in liters per minute

• When ‘Pressure in H2O’ is illuminated the LED displays system pressure in inches of water

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Display Indicator lights

• The ‘Vacuum in H2O will only illuminate when the smoke machine senses that the system pressure is lower than ambient atmospheric pressure

• The ‘Polarity Protect’ indicator will illuminate if the power lead connections at the battery are reversed

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Display Indicator lights

• The ‘Pass’ or ‘Fail’ light will illuminate after a 5 minute leaks test has been completed

• The three orifice size indicator lights indicate the size the internal restriction in the smoke machines output port

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Display Indicator lights

• The ‘Off/Decay’ light indicates that flow of smoke from the machine is turned off

• When the ‘On’ light is illuminated there should be a continuous flow of smoke passing through the smoke vapor hose

• The ‘Low Flow’ indicator light indicates that the machine is operating in pulsed mode. A puff of smoke is sent through the smoke vapor hose every few seconds.

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Inches of Water

• Very low levels of pressure or vacuum are measured in units of inches of water

• The amount of vacuum applied to the tip of a straw that will cause the water in the straw to rise one inch equals a vacuum level of 1 inch H2O

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Inches of water - pressure

• Pressure can be measured in inches of water using a manometer

• A ‘U’ shaped glass tube is partially filled with water

• One end of the tube is open to atmospheric pressure

• The other end is connected to the pressure being measured

• The difference between the water levels is measured in inches

Pressuresource

Open to atmosphere

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Select the type of gas

• After the power leads are connected to the battery you have 5 seconds to select the type of gas being used in the test.

• The default value is ‘AIR’ = shop air

• If you are using compressed nitrogen gas press ‘Display Select’ until ‘n2’ is displayed • If you are using compressed carbon dioxide

press ‘Display Select’ until ‘CO2’ is displayed

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Select the display type

• Pressing the ‘Display select button cycles through the three types of data displays: – Orifice Size– Flow rate– Pressure / Vacuum

• If you are performing a pass/fail leak test the display must be set to orifice size to finish the test• When the display is set to pressure the vacuum

LED will illuminate if the system pressure is below the ambient atmospheric pressure

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Start button functions

• Pressing the ‘Start’ button will begin sending a steady stream of smoke through the smoke/vapor hose

• This begins a timed 5 minute test of the EVAP system

• Pressing the ‘ Start’ button a second time will set the smoke machine to pulsed low flow mode

• While in ‘Low Flow’ mode the smoke machine will make a clicking noise

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Turning off the machine

• The machine will automatically shut down after the completion of the 5 minute test or after 8 minutes of inactivity

• Holding the ‘Start’ button depressed for a few seconds will force the machine into shutdown mode

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Low battery voltage warning

• A ‘Lo bAt’ warning message will be displayed if the battery voltage level is below 11.0 volts

Lo bAt

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Remote start/stop

• The smoke machine comes with a remote key fob that is used to start and stop the flow of smoke

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Max Pressure and Flow Rate

• Maximum smoke pressure = 13.0 inches of H20

• Maximum flow rate = 10 liters per minute

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OBDII EVAP System

Intake manifold

Purge Solenoid

Vent Solenoid

Charcoal canister

Sealed gas cap

Roll over valve

Fill limit vent valve

EVAP Pressure sensor

Pressure release valve

EVAP test port

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Canister and vent solenoid• The charcoal canister and vent solenoid are

located under the vehicle and within a few inches of the fuel tank

Vent solenoid

Vent to atmosphere

Charcoal canister

Vapor line to tank

Purge line

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Purge solenoid

• The purge solenoid controls the rate at which gasoline vapors are removed from the canister during the drive cycle

• It is normally found under the hood

Purge line connects to

canister

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EVAP Monitor

• All OBDII systems run a non-continuous monitor on the evaporative emissions system at least once in every trip

• There are two test performed in the EVAP system monitor:– A system integrity [leak] test– A system performance test [flow test]

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EVAP Monitor

• If either test fails in two consecutive trips the Check engine light will illuminate and a code will be set

• EVAP system codes range from P0440 through PO470

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EVAP System integrity test phase 1

• During the first phase of the test the PCM commands the vent solenoid closed and pulses the purge solenoid to create a partial vacuum within the tank

Purge Solenoid

- openVent

Solenoid - closed

EVAP Pressure sensor

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EVAP System integrity test [leak test]

• After enabling criteria are met the PCM commands the canister vent solenoid closed and sends a PWM current [pulse width modulated] to the purge solenoid to allow a small partial vacuum to build up inside the gas tank

• When the pressure inside the tank reaches a preset amount – typically around 10 inches of water – the purge valve is commanded closed

• Pressure inside the tank is monitored for the next few minutes

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EVAP System integrity test phase 2

• When the pressure sensor reaches a preset value the PCM closes the purge solenoid. The vent solenoid remains closed. The PCM monitors the change in pressure inside the tank for the next few minutes.

Purge Solenoid- closed

Vent Solenoid - closed

EVAP Pressure sensor

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EVAP monitor – system integrity test

• If there is a rapid rise in tank pressure after the purge solenoid closes there must be a large leak – greater than .040” . The EVAP integrity test fails.

• If the tank pressure slowly rises over a period of several minutes the total leak size must be smaller than .020”. The EVAP integrity test passes.

• The EVAP monitor then begins the system flow test.

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EVAP monitor – flow test

• The flow test looks at the changes in short term fuel trim as the duty cycle applied to the purge solenoid is altered by the PCM.

Purge Solenoid- cycling

Vent Solenoid

- open

Upstream oxygen sensor

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EVAP monitor – flow test

• During the flow test the canister vent solenoid is open and the duty cycle [PWM] applied to the purge solenoid is slowly increased until it reaches 100% open.

• The PCM looks at 3 factors:– Short term fuel trim [STFT]– Idle rpm– IAC or Electronic throttle control idle position

• If any of these factors change significantly as the duty cycle on the purge solenoid is increased the EVAP monitor passes

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Troubleshooting EVAP system leaks• If the check engine light is illuminated and a

scan tool reveals a code for an EVAP system leak the smoke machine is the best tool to locate the source of the leak.

• A scan tool may be required to actuate the canister vent solenoid to the closed position.

• Leave the scan tool connected after verifying the code

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Remove Schrader valve

• Before connecting the smoke machine to the test post remove the Schrader valve

• The Schrader valve has left hand threads – turn the tool clockwise to loosen it

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Install the test port adapter

• Thread the end of the adapter on to the test port

• Hand tight only --- Do not over-tighten

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Connect the smoke hose

• The smoke hose is connect by pushing the cone shaped hose end into the adapter hose

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Setup smoke machine

• Connect the smoke machine to shop air [or CO2, N2 if available]

• Connect the electrical leads to the battery – check that the polarity indicator is not illuminated

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Go to Scan tool

• In the scan tool menu find the test menu for functional test

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Scan tool EVAP test menu

• Find the EVAP test that allows the scan tool to open and close the canister vent solenoid

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Scan tool EVAP test menu

• Select vent solenoid (on/off)

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Scan tool EVAP test menu

• Use the Y/N buttons to toggle the vent solenoid on and off

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Scan tool – tank pressure sensor

• The scan tool page here displays the tank pressure in inches of mercury

• To convert inches of mercury to inches of water multiply by 13.5

• The pressure measured here is 9.86 inches of water

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Select the orifice size

• Press the orifice size button until the correct orifice size is displayed:– .020” for vehicle built after

MY 2000– .040 for built between MY

1995 and 1999

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Start 5 minute test

• Press the Start button to begin the 5 minute test

• You can change the display to pressure H20 or flow L/M during the test but the display must be returned to orifice size to get the pass/fail indicators to function at the end of the test

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Check for evidence of smoke leakage

• During the test raise the vehicle to examine all of the components of the EVAP system for evidence of leakage

• The vent solenoid shown here is frozen in the open position

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Check the gas cap seal

• Open the fuel filler door to check the condition of the cap seal

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Pass / fail indicators

• If there are any leaks detected the fail indicator light should illuminate at the end of the test

• The off/decay light should also be on to indicate that the flow of smoke has been turned off

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Small leaks

• Leaks that are too small to release visible smoke may be detected by shining the UV light along the hoses and around the canister. Condensed smoke oil should glow green/yellow around any small leaks

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Finding exhaust system leaks

• A spare battery or jump box can be used to power the smoke machine

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Cone adapter for exhaust

• If the vehicle has dual exhaust with a crossover one tailpipe may need to be plugged

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Muffler drain

• Many mufflers have a condensation drain hole near the bottom

• Smoke coming out of the drain shown here is normal• Seal the drain hole with a piece of tape to prevent the

smoke from the drain masking any other exhaust leaks

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Exhaust flex joint• Pay special attention to the flex joint in the

exhaust where the front pipe connects to the exhaust manifold.

• Shine the UV light onto the exhaust manifold to detect small cracks

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Finding intake leaks

• Since the throttle plate never closes completely you will need to plug the intake upstream of the throttle plate.

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Connect smoke hose to manifold• There are normally several manifold taps

that you can connect to

• For this vehicle we disconnected the vacuum supply line for the purge solenoid

Canister purge solenoid

Vacuum supply line

Smoke hose

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Find the leaks

• When smoke is introduced into the manifold even very small air leaks will emit smoke

Distorted throttle body

gasket

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Other uses

• The smoke machine is not limited to on car testing.

• The seals and gaskets of a rebuilt engine can be smoke tested prior to installation

• If you can figure out a way to seal off the open areas of the system you can smoke test almost anything