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.

3. 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

4. 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

5. 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

6. Smoke machine components
Smoke oil
Large tailpipe plug
Smoke dispersal adapter
12 volt power cables
UV light source
Vacuum pump adapter
Wireless remote
Exhaust pipe cone adapter
UV glasses
Plugs
Smoke outlet hose
Schrader valve removal tool
EVAP test port adapter

7. 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

8. Ultraviolet Light source
An LED type UV flashlight is used to pinpoint the source of leaks
Condensed smoke oil will glow green/yellow when exposed to UV light

9. Never look directly into the UV light
Exposure to UV light can cause permanent damage to the retinas of your eyes
Yellow UV safety glasses should be worn whenever working with UV light sources

10. Condensed smoke oil
Smoke vapor will generally not glow when exposed to UV Light
A small amount of smoke vapor will condense around the places that the smoke leaks out of. This liquefied smoke will glow

11. 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

12. Checking the oil
Full Mark
Smoke oil is a clear liquid so it is difficult to see the level on the dipstick without the aid of UV light

13. Adding oil
If the oil level is low add a few ounces of oil – do not overfill

14. 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

15. Hanging the smoke machine
When the smoke machine will be used near the engine the machine can be hung from the hood latch
Hanging the smoke machine

16. Air Line coupler
The correct type of coupler needs to be installed to connect the smoke machine to the shop’s compressed air hoses

17. 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

18. Vapor hose
The vapor hose is used to inject smoke into the system being tested

19. 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

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

21. 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

22. 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.

23. The EVAP test port is located on the vapor line between the purge solenoid and gas tank
The cap is normally a light green color
The port is normally located under the hood but is occasionally found underneath the car

24. 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

25. Vacuum Pump
During the test a small amount vacuum is applied using a hand held vacuum pump

26. Screen Display

27. 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

28. 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

29. 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

30. 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

31. 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.

32. 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

33. 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
Pressure
source
Open to atmosphere

34. 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

35. 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

36. 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

37. 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

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

39. Remote start/stop
The smoke machine comes with a remote key fob that is used to start and stop the flow of smoke

40. Max Pressure and Flow Rate
Maximum smoke pressure = 13.0 inches of H20
Maximum flow rate = 10 liters per minute

41. Pressure release valve
OBDII EVAP System
EVAP test port
Purge Solenoid
Vent Solenoid
Charcoal canister
Intake manifold
Sealed gas cap
EVAP Pressure sensor
Roll over valve
Pressure release valve
Fill limit vent valve

42. 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 to atmosphere
Charcoal canister
Vapor line to tank
Vent solenoid
Purge line

43. Purge line connects to canister
Purge solenoid
Purge line connects to canister
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

44. 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]

45. 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

46. EVAP System integrity test phase 1
Purge Solenoid
- open
Vent Solenoid - closed
EVAP Pressure sensor
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

47. 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

48. EVAP System integrity test phase 2
Purge Solenoid
- closed
Vent Solenoid - closed
EVAP Pressure sensor
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.

49. 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.

50. EVAP monitor – flow test
Purge Solenoid
- cycling
Vent Solenoid - open
Upstream oxygen sensor
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.

51. 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

52. 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

53. 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

54. Install the test port adapter
Thread the end of the adapter on to the test port
Hand tight only --- Do not over-tighten

55. Connect the smoke hose
The smoke hose is connect by pushing the cone shaped hose end into the adapter hose

56. 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

57. Go to Scan tool
In the scan tool menu find the test menu for functional test

58. Scan tool EVAP test menu
Find the EVAP test that allows the scan tool to open and close the canister vent solenoid

59. Scan tool EVAP test menu
Select vent solenoid (on/off)

60. Scan tool EVAP test menu
Use the Y/N buttons to toggle the vent solenoid on and off

61. 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

62. 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

63. 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

64. 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

65. Check the gas cap seal
Open the fuel filler door to check the condition of the cap seal

66. 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

67. 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

68. Finding exhaust system leaks
A spare battery or jump box can be used to power the smoke machine

69. Cone adapter for exhaust
If the vehicle has dual exhaust with a crossover one tailpipe may need to be plugged

70. 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

71. 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

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

73. Connect smoke hose to manifold
There are normally several manifold taps that you can connect to
Canister purge solenoid
Smoke hose
Vacuum supply line
For this vehicle we disconnected the vacuum supply line for the purge solenoid

74. Distorted throttle body gasket
Find the leaks
When smoke is introduced into the manifold even very small air leaks will emit smoke
Distorted throttle body gasket

75. 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