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FUNCTIONAL INSPECTION
The functional inspection is the only portion of the smog inspection actually performed by the smog
technician. This test will insure proper operation of the following components and/or systems.
A. Engine Ignition Timing
B. Check Engine Light
C. Gas Cap & Filler Neck
D. Exhaust Recirculation Valve (EGR)
E. Fuel EVAP Test (LPFET)
A. Engine Ignition Timing
Your vehicle's engine ignition timing will be inspected during the smog test. The smog technician will insure ignition timing is set properly, and the system is supplying electric current to the sparkplugs at the correct intervals.
Spark, usually around 15,000 volts, is created at the engine's ignition coil.
Electricity is delivered to the coil, a spark is generated, then sent to the distributor. It is the distributors duty to route the spark to the correct spark plug, at the correct time. The timing inspection will insure the distributor is sending the spark plugs energy at the exact moment required for optimum air/fuel combustion. Adjusting a vehicle's ignition timing is performed by rotating the distributor in the clockwise or counterclockwise directions.
Failed Ignition Timing: Engine ignition timing is measured in degrees. A good example of a timing failure would be in the case where ignition timing is required to be set at 15 degrees Before Top Dead Center (BTDC) and instead is set to 10. This fault will cause a functional failure, as well as increase Hyrdocarbon (HC) emissions. One or two degrees off will not cause a smog failure. California's emissions standards allow timing to be up to 3 degrees +/- off the manufacturer's required setting; resetting is recommend.
Important: Some late model vehicles may not have an ignition distributor, and therefore no timing adjustment or testing of the ignition system is required. On these engines, timing is controlled electronically by the Engine Control Unit, also known as the ECU. Any ignition fault will automatically trigger a check engine fault, more then likely illuminating the check engine light.
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B. Check Engine Light (MIL)
My car's check engine light is on. Will I fail the smog test? This is probably the number one question we get. Contrary to public belief, the
check engine light, also known as the malfunction indicator lamp, being constantly illuminated is an automatic smog failure. Vehicle manufacturers have
placed the check engine light inside the passenger compartment
to inform the driver that there has been an engine or drivetrain malfunction.
Very often your vehicle's check engine light will be illuminated but you will not be noticing any driveability issues. This is due to the fact that once the check engine light, also known as the malfunction indicator lamp (MIL) goes on, the engine's ECU (computer) begins to operate under pre-programmed data rather then of real-time. In other words, the computer has sensed an error from an emissions component, and replaced the data from that component with data from it's memory. This may not be the case in all check engine light failures, but it is in the majority.
The OBDII Emissions Computer System: Depending on the year, make, and model of vehicle you own this system is different. If you own a 1996 or newer car, truck, SUV, van, or RV, it is equipped with an On Board Diagnostics system and computer link, called OBD II; as opposed to OBD I which older vehicles are equipped with. The OBD II Diagnostic system is designed to monitor all aspects of an engine's emissions control system, and report this information to a central database within the ECU (computer). This information is processed and checked against the computers pre-determined values for various inputs levels and performance patterns. If any problems are found, the computer will determine whether to alert the driver or not. If a decision has been made to alert the driver of an emissions problem, the "Check Engine" or "Engine Malfunction" light will illuminate on the vehicle's dashboard. In more serious emission conditions the computer may even begin to rapidly flash the "Check Engine/Malfunction" light indicating to the driver, that the vehicle needs immediate diagnosis/repair attention.
OBDII & The Smog Machine: During the smog test (assuming you have a 1996 or newer vehicle) your vehicle will be "hooked" to the smog machine via it's OBD II link/connecter. The OBD II link will relay all "Check Engine" conditions along with stored trouble codes within it's database to the smog machine while the vehicle is being tested. If any trouble codes are present which caused the check engine light to illuminate either regularly or intermittently, the vehicle will fail the smog inspection. Here's the tricky part... some codes do not illuminate the check engine light, but do cause smog check failures; and that's where "readiness flags" come in.
Readiness Flags: There are two types of codes, bad codes and good codes. The good codes are the Readiness Flags. Readiness Flags indicate that certain emissions systems which the OBD II computer has been monitoring have passed internal self monitoring tests, indicating that those systems are working properly. If the smog machine detects that there are certain Readiness Flags which have not set, it will cause your vehicle to fail the smog test.
In order to set all the proper Readiness Flags the OBDII system must complete at least one good drive cycle (in some cases two or three). A good drive cycle is a sequence of passing internal tests which the OBDII computer runs while your vehicle is being driven. This insures all emissions systems are functioning properly. A drive cycle usually requires one to two weeks of ordinary everyday driving.
Trouble Codes: The bad codes are actual Trouble Codes. These codes indicate that the OBD II computer has detected a problem within the emissions system. The trouble code will specifically indicate the component and problem which was found. Newer vehicle's have very complex codes in the thousands. Smog check repair centers can retrieve the trouble codes from the OBDII and inspect the component/s which the codes indicate. Generic trouble code failure will be indicated on your vehicle's vehicle inspection report (VIR).
C. Gas Cap & Filler Neck
During the smog test your vehicles gas cap and filler neck will also be inspected. They will have to be
of proper fit and design. The gas cap must be able to hold
pressure at factory specifications and the filler neck must
not be altered to accept leaded gases. This test is to insure
the vehicle is not polluting fuel tank fumes through the
filler neck or using the wrong type of fuel. Most vehicles
pass this portion of the test with no problems. If your
vehicle's gas cap appears to be broken it may not
pass.
The state allows a vehicle owner to purchase a new gas cap from the smog station during the smog test. This allows the smog technician to continue the smog test, without having to fail the vehicle. The vehicle owner also has the choice of purchasing a new gas cap at a future date, however this would require the smog technician to fail the vehicle at the time of inspection. After a new cap is purchased a new smog inspection must be performed.
D. Exhaust Gas Recirculation Valve (EGR)
Some vehicles have to also undergo an EGR
valve inspection. EGR stands for exhaust gas recirculation. And that
is exactly what this component does. The EGR system recirculates
burned up exhaust gases back into the combustion chambers. Since
these recycled exhaust gases have already been in the combustion
chambers once, they have burned up most of their fuels, means there
is now much less real fuel in the chambers to ignite. This keeps the
chamber temperatures down and thus reduces NOx emissions. The EGR
valve should be inspected to insure its proper operation. A working
valve should be able to open its passage using manifold vacuum.
Manifold vacuum is created during the engine's intake cycle. The
high demand for air during this cycle creates a vacuum within the
engine's intake manifold. This vacuum is then used to control
several important functions within the vehicle, including
controlling the EGR valve. Some vehicles even rely on this vacuum to
control their heating and air-conditioning components. The EGR
system is prone to collecting carbon build-up. Some vehicle
manufacturers recommend cleaning this component an a regular basis.
Please Click on "Under Your Hood" for more information on EGR valves
and testing procedures. The following late model vehicles are
equipped with EGR systems - Acura, Audi, Buick, Chevrolet, Chrysler,
Dodge, Plymouth, Fiat, Ford, GM, GMC, Saturn, Honda, Hyundai,
Infiniti, Isuzu, Jaguar, Jeep, Lexus, Mazda, Mercedes Benz,
Mitsubishi, Nissan, Peugeot, Porsche, Renault, Land Range Rover,
Saab, Saturn, Subaru, Suzuki, Toyota, Volkswagen, VW, Volvo, and
Winnebago.
E. Low Fuel Pressure Evaporative Test (LPFET)
November 1, 2007 is
the date BAR has targeted as the start date for the EVAP Functional
Test (LPFET). This will be in addition to the Smog Check test. 1976
to 1995 model year vehicles; car, truck, van, SUV, RV and motorhome will be tested, which includes all pre OBDII vehicles subject to Smog Check. The most important impact
on consumers is that the emission reductions will improve air
quality and reduce their health risks. This test is designed to
insure your vehicle's fuel evaporative system is not leaking gas
fumes in to the atmosphere. It is estimated that over 7,000,000
vehicles will need to be tested each year and of those 11% will
fail. The average cost to repair a failed EVAP system is estimated to be approximately $250.00.
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