EVAP Test Questions
1. Vehicles sold in the US first began using devices to control evaporative emissions with the introduction of OBD-I and OBD-II?
True
False
2. All OBDII systems check for evaporative emissions problems the same way?
True
False
3. The actual test performed for US vehicle certification of evaporative emissions is called the SHED test?
True
False
4. Which of the following equivalent orifice sizes is not an actual regulatory standard for an evaporative emission leak?
A.)0.020”
B.)0.080”
C.)0.040”
D.)0.008”
5. Tech A says “Purging the Canister is when air flows into the vent and through the Canister, then through the purge valve and into the intake manifold.” Tech B says “Purging the Canister is when the Leak Detection Pump is turned on to draw the air into the vent and through the Canister.” Who is correct?
A.)Only Tech A is correct
B.)Only Tech B is correct
C.)Both Tech A and B are correct
D.)Neither Tech A or B are correct
6. Evaporative emissions increase due to
A.)Fuel Temperature increase
B.)Air Temperature increase
C.)Fuel Volatility increase
D.)All of the above
7. Tech A says “evaporative emissions occur when the vehicle is running.” Tech B says “evaporative emissions occur because the vehicle had recently been running or is running.” Who is correct?
A.)Only Tech A is correct
B.)Only Tech B is correct
C.)Both Tech A and B are correct
D.)Neither Tech A or B are correct
8.A Leak Detection Pump (LDP) system uses a Fuel Tank Pressure (FTP) Sensor.
True
False
9. Tech A says ”The vehicle can’t go into a purge cycle after refueling until the fuel tank level is below ¾ full” Tech B says “ The vehicle can only go into a purge cycle when the fuel level is between ¼ - ¾ and not at ANY other time!”
E.)Only Tech A is correct
F.)Only Tech B is correct
G.)Both Tech A and B are correct
H.)Neither Tech A or B are correct
10. What does ORVR stand for?
______
11. An EVAP leak as small as .020” is over 30 times the allowableexhaust emission standard.
True
False
12.A gas cap can cause a P0442 “small leak” or P0455 “gross leak” on a 1998 OBDII non-enhanced EVAP system.
True
False
13. Which manufacturer tests the EVAP system for leaks 5 hours after the vehicle is shut off?
1) Honda
2) Toyota
3) BMW
4) None of the above
14. When did EVAP systems first start appearing on car?
1) 1950’s
2) 1960’s
3) 1970’s
4) 1980’s
15. You can tell the difference between an OBDII enhanced and non-enhanced EVAP system by the vehicle having (enhanced) or not having (non-enhanced) an EVAP test port (The green cap).
True
False
Answers:
1. False.
The US Auto Industry first began using devices to control evaporative emissions in the 60’s. By the late 70’s, charcoal canisters and purge valves were a common site in automobiles. Federal Regulations didn’t mandate evaporative emissions until the 70’s.
2. False.
The self testing of EVAP systemsvaries from manufacturer to manufacturer. There are many different systems in use today like: non-enhanced, enhanced, NVLD, EONV, LDP, Key-OFF and MD-TL.
3. True.
This has been a commonly used testing procedure by our government for years.
4. (D)
1996 to 1999 leak rate standard is .040”. The green states went to a 0.20” standard starting in the year 2000. As of July 2006 there is no standard of 0.008”
5. (A)
The LDP is not used for purging the system. It is used for checking the system for LEAKS!
6. (D)
Many things can aid in the evaporation of fuel.
7. (C)
Like above, many things can aid in the evaporation of fuel.
8. False.
A system that is using an LDP does NOT use a fuel tank pressure sensor. It uses a “Reed Switch” to give the PCM the information it needs to determine leak rate size.
9. (H)
Fuel level is part of the “Pre-Condition Requirements” for self testing.The vehicle can go into a purge cycle at any time.
10. On-board Refueling Vapor Recovery
11. True.
12. False.
This system checks to see if purge occurred when purge was commanded. This system does NOT check for leaks.
13. (2)
The Toyota system is called Key-OFF. It tests the system under stable conditions. It will start it’s testing 5 hours after the key is turned off. If conditions are still NOT stable after 5 hours,it will stop and wait an additional 5½ hours.
14. (2) or (3)
Answers 2 or 3 are acceptable.EVAP system first started appearing on vehicles in the 60’s, BUT the Federal Regulations didn’t mandate evaporative emissions until the 70’s. This question is important because we need to understand EVAP systems have been on vehicles for over 35 years. (NOT since OBD-II)
15. False
The service port (or green cap) is not on all makesor models. In fact some manufacturers, like Toyota have stopped installing them on ALL models starting in 2006.