How to Pass a Smog Check

Test Preparation will Help

Like it or not, more and more states are starting to adopt California's stringent smog check standards as part of their own pollution control efforts. In theory, smog check programs are designed to keep the air clean. Clean air to breathe is a good thing. In practice it can seem for the consumer that the program amounts to another source of expensive repair bills. A big repair bill is a bad thing. The fact of the matter is if that engine under the hood has seen its better days and is spewing enough toxic crud into the air to give Chernobyl a run for its money, then it should be fixed as soon as possible. If a smog check program forces motorists to address and repair poor running, worn out, polluting engines, then it does what it is supposed to do.

The problems come when an otherwise clean running engine fails a smog check due to a malfunctioning component, misadjusted system, a part that has parted ways with its function, or worse-a bureaucratic roadblock. The solutions to these problems are easy. Get your engine running the best it can, and be certain all smog devices are working as they should before rolling into the smog check station. Making sure that your car, truck, SUV, minivan or contraption is running efficiently not only helps keep the air clean, it can also help save you some money. An engine burns fuel more efficiently when kept in good order, and with gas prices always creeping higher, efficiency can add up to savings.

Different Strokes

Modern engines use a myriad of smog control devices depending on their type, year of manufacture, and type of vehicle. For these reasons it's smart to take a look either under the hood, or into the owner's or service manual and do your own pre-inspection test long before hitting the smog check establishment. Vehicles will often have timing specs and diagrams as to the ins and outs of pollution control systems on a placard right under the hood. Beyond the vehicle-specific systems, there are obvious steps that can help your vehicle pass a smog check.

The first and foremost step is to educate yourself and check out the smog regulations in your state. Rules and regulations can be Byzantine in their complexities, and knowing is half the battle when it comes to passing the test the first time in. In California, vehicles are placed on a dynamometer. This machine simulates actual driving conditions by placing a load on the engine as the vehicle is strapped down and the drive wheels are bolted to a set of rollers. A computer stores vehicle information and, if numbers don't match up after the test, problems can arise. A larger than stock set of tires, for instance, can throw off the dynamometer results and cause an otherwise clean-running vehicle to fail the smog test. Studying for the smog test is a good preparation. Your local DMV is a good place to start. Unless you enjoy a good DMV line or bureaucracy in general it is a much better idea to learn first how to avoid any surprises later.

Keep it Clean

On the nuts and bolts side of things, the parts and pieces that comprise your vehicle's pollution control systems must be in good working order. EGR valves should be working properly. Air or smog pumps should be pumping. All vacuum tubing and connections should be secure and not cracked. Oxygen sensors should be sensing. Modern vehicles have a built-in diagnostic system to alert the driver of potential problems in the form of the dreaded check engine light, or Malfunction Indicator Light (MIL). Ignoring this and driving into the smog check station is a bad idea. If it can be adjusted, ignition timing should be set to manufacturer specifications. Incorrectly set ignition timing can alter tailpipe emissions as it has a major effect on the combustion process.

Above and beyond the most important weapon in your vehicle's arsenal in the war against smog is the catalytic converter. A catalytic converter greatly reduces the amount of carbon monoxide, hydrocarbons, and nitrogen oxides coming out of your tailpipe. As the exhaust exits the engine it runs into the converter, which contains a honeycomb of platinum to separate the atoms of aforementioned bad molecules and recombine them into good ones. Over time these honeycombs lose their power and can become clogged, vastly reducing the converter's efficiency. Since catalytic converters operate most efficiently while good and hot, driving the vehicle around for an hour or so before the test is a good idea.

Finally, there is no cheating the smog test. The best way to pass is to make sure all is well. If for some reason the vehicle still fails, then it could be time to consider repairs.

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