Wednesday, February 22, 2012

O2 for You

Oxygen sensors are by far one of the most important sensors used to control the engine. This sensor does just what the name implies, it senses oxygen but specifically it looks at the oxygen content in the exhaust stream. When the computer that controls the fuel injectors needs to see if it is doing a good job managing the air/fuel ratio it will look to the O2 sensor.

The amount of oxygen in the exhaust is directly proportional to how much fuel the injectors are adding to the incoming air. If oxygen content is high it indicates a lean mixture which means that there is not quite enough fuel. If oxygen content is low it indicates a rich mixture or a situation with too much fuel.

The O2 sensor is a voltage generating sensor. An electrode extends from the senor tip into the exhaust stream so that it can pick up oxygen molecules in the exhaust. The other end of this electrode extends out of the exhaust and is actually exposed to ambient air on the outside of the exhaust pipe. This electrode works kind of like a small battery comparing the exhaust to the outside air creates a potential difference electrically speaking. The greater the difference in the oxygen content between the inside and the outside of the pipe the higher the potential difference or the higher the voltage the sensor produces. This voltage is the signal that the computer reads.
O2 sensor cutaway.

In order for the sensor to operate it must be heated to 600° F. On older vehicles the engine and the exhaust had to first warm up in order for the O2 sensor to come online. Most exhaust manifolds will get up to 600° but it wouldn’t happen until the engine had been running for several minutes. During this warm up period the computer would disregard the O2 sensor and function strictly off of the other sensors. This is known as open-loop operation. Once the O2 sensor warms up the computer can begin to look to it for feedback. This is called closed-loop operation. Open-loop is imprecise and the engine loses efficiency when running in this mode. Because of this newer O2 sensors are fitted with a electric heater circuit so that the sensor will heat up faster and get into closed-loop operation sooner.

The voltage signal usually fluctuates between .1 and .9 volts. This seems like a tiny signal but it is enough for the computer that is reading the sensor. The midpoint of the sensor range is .45 volts. Anything above .45 is rich anything below .45 is lean. Usually under normal operation the voltage signal will fluctuate smoothly up to .9 and then back down to .1 volts. The reason this happens is because the computer is purposely switching the mixture between rich and lean. This happens so that there will be some oxygen that makes it through the combustion process. The extra oxygen that makes it through is needed by the catalytic converter in order to allow proper oxidation of some of the harmful pollutants that must be handled by the catalyst.

When the O2 sensor shows a signal that isn’t good the computer will be smart enough to know that there is a problem. Two different problems are possible and sometimes the computer can tell if it’s one or the other. The signal might be legitimate but it indicates a problem with the mixture. This might be because of some malfunction somewhere else in the engine controls causing a rich or a lean mixture. Another sensor might be acting up, the injectors might be leaking or sticking open, there may be a vacuum leak at the intake manifold. Anything that causes the computer to lose the ability to accurately regulate fuel will affect the reading of the O2 sensor.
Normal O2 sensor voltage traced on a digital oscilloscope. Notice how it switch from .2 to about .8 a few times
per second. This is the best way to test an O2 sensor.

Sometimes the O2 sensor signal will be a bad signal because the sensor itself is bad. The signal may get stuck at a high or a low voltage, or the rationality of the signal may be all over the map with the voltage spiking upward and downward in an erratic manner. This is a problem with the sensor and it must be replaced.
This is a biased O2 sensor signal because it is switching but it won't get down to .2 volts like it needs to.

The other thing and perhaps the most common thing that an O2 sensor does when it goes bad is it gets slow. The signal switches back and forth as the air/fuel mixture goes from rich to lean but the signal doesn’t keep up with the actual air/fuel ratio. The signal will only cross the midpoint of .45 1 per second or once every few seconds. This is a bad thing because it does not give good feedback to the computer. The problem with a slow O2 sensor is that the computer quite often cannot tell that the sensor is getting lazy. The fuel economy of the vehicle will plummet and the throttle response of the engine will feel sluggish. This condition sets in very slowly over time so the driver of the vehicle may not realize that there is a problem.

An older style O2 sensor that has just
one wire.
Some manufacturers suggest that the O2 sensor be replaced every 100k miles or something like that. Many times this is not a bad idea. In the early days of fuel injection these replacement intervals were so common that a few cars and trucks actually had a light on the dash that would illuminate when it was time to replace the O2 sensor. Since most manufacturers want to make their cars appear to be inexpensive to maintain, they have cut out a lot of the services that they used recommend. Some of these services really aren’t required anymore but some of them might still be a good idea.

The best way to test an O2 sensor is with a digital oscilloscope. This tool is capable of looking at the voltage from the sensor and plotting it on a graph so that you have a graphic representation of what the voltage is doing. A digital voltmeter will also work but you can’t see the voltage fluctuations as accurately as you can with a scope. While monitoring voltage you can purposely cause the engine to go lean by doing something like pulling off a vacuum line and creating a situation where the engine is drawing in air that it can’t measure. The mixture can be forced rich by using a propane torch or something like that to flow hydrocarbons into the intake. The voltage signal should immediately respond to such manipulations.

Air Fuel Ratio Sensor

Every new vehicle on the road today uses a different type of O2 sensor that is referred to as an air/fuel ratio sensor, sometimes it might be called a wide-band O2 sensor. The regular O2 sensor produces a voltage signal based on oxygen content and the computer can tell if the mixture is rich or lean but it cannot tell how rich or how lean because the O2 sensor works over a very narrow range. A/F sensor can not only tell if the mixture is rich or lean but it can also tell how rich or how lean.

An A/F sensor. This one has 5 wires. This many wires
is a sure sign that it not a normal O2 sensor.
The stoichiometric air/fuel ratio is 14.7:1. The regular O2 sensor can tell you if you are north or south of that ratio and that is all. The A/F sensor can read a mixture as rich 10:1 and as lean as 19:1. This makes it much easier for the computer to be very precise in its control of the air fuel ratio. More precise control leads to more power on less fuel with lower emissions every time.

The A/F sensor operates at about 1200° F so it too will have a built in heater circuit in order to bring it online soon after the engine starts. The voltage and the amperage output from the A/F sensor are important. Voltage above 3.3 volts with positive amperage indicates a rich mixture. Negative amperage and voltage below 3.3 volts indicates a lean condition. Usually the only good way to check A/F sensor output is to use a scan tool to view sensor readings in the data stream.

High performance tuners will usually install a wide-band A/F sensor somewhere in the exhaust stream so that they can monitor the air/fuel ratio on the fly. Even in an old hot rod that is carbureted installation of a sensor like this, hooked up to a display that can always show the reading, is great for making sure that the car is running at its peak. If the A/F mixture were to get too lean then it might cause serious engine damage.

Upstream Downstream

Every new vehicle on the road today will have a minimum of 2 oxygen sensors if it is a 4 cylinder engine, and if it is V engine it will 3, 4 or maybe even 6 O2 sensors. The primary O2 sensors or upstream O2 sensors are located in the exhaust manifolds close to the exhaust ports in the cylinder heads. These are the sensors providing feedback concerning the A/F ratio. The secondary or downstream O2 sensors are located much further down the exhaust pipe after the catalytic converter. These sensors are there simply to monitor the function of the catalyst.

After the exhaust passes through the catalytic converter any oxygen that is in the exhaust should be used up in the chemical reactions that take place in the cat. This will mean that the voltage readings from the monitoring O2 sensor will be flat and will not switch up and down like the primary sensors do. If the signal from the downstream sensor comes to resemble the signal of the upstream sensor then the computer knows that there must be a problem with the cat, and it will set a trouble code P0420 for catalyst inefficiency and illuminate the check engine light.
Upstream sensor (left), downstream sensor (right). They are not always this close together.

The O2 sensor is a critical piece of control equipment for any fuel injected vehicle. A good sensor can keep the vehicle running right for a very long time. If your check engine light comes on, don’t ignore it. Any problem with any sensor can compromise the way the vehicle is running, but a bad O2 sensor will cause emissions to go up, and power and fuel economy to go down. What could be worse?

Monday, February 20, 2012

The Worst Cars In the World: Cadillac Cimarron

What a major embarrassment! Cadillac was already skidding out of control when the Cimarron was released, and this car did nothing to help them. This huge mistake of a car was actually symptomatic of deeper problems at GM as they were starting to lose market share in a way that they had never known. The Cimarron makes the Cadillac Catera, Caddy’s subsequent attempt to build a small car, look like a fantastic bit of engineering.

Look at the fancy emblems on the taillights.
In the early 80’s the effects of the Middle East oil embargo of the seventies were still being felt and many auto companies were downsizing their vehicles so that they could be more fuel efficient. Front wheel drive was also starting to catch on. Cadillac had a history of building huge land yachts for people who might generally have more dollars then cents. Nevertheless, they felt it important to come up with an offering that would provide better fuel economy but still pamper the driver and passengers with the amenities that were expected in a Cadillac. BMW was having success selling small luxury cars so Cadillac thought that they should join in. Turns out the Cimarron really didn’t have any of the amenities that a luxury car ought to have yet it was priced as if it did.

The driving gloves are just plain silly!
The Cimarron hit the market for the 1982 model year and was actually found in the Cadillac lineup for 7 years. During these very dark times for GM and for the Cadillac line, not very many of these chintzy little pieces of junk were sold and it’s no wonder. The biggest problem with the Cimarron was that it was based on GM’s J-body platform and not much was done to really differentiate it much from other J-body cars like the Chevy Cavalier, and the Pontiac Sunbird. GM at first called the car Cimarron by Cadillac. As if turning the name around made it special or somehow set it apart from other marginal Caddies of the day.

The Cimarron was too expensive for what the customers actually received. The 4 cylinder engines were too weak for the regular Cadillac owners and the overall look and feel of the car were not anything special that could set the car apart from other compact sedans in the J-body family. Eventually a V6 option was added to the line and even made standard but it didn’t really make a difference. You can put a V6 in a tub and it will have more power but guess what, it’s still a tub.

The new redesigned 1986 Cimarron. How exciting!
Some companies get so caught up in trying to save money on the development of new models that they get into the practice of badge engineering. This means that they design a car platform and put several different badges on it. Of course in the end they aren’t fooling anyone, and neither did Cadillac with the Cimarron. Why pay thousands of dollars extra for a car that has nothing extra to offer beyond the hood ornament with a wreath and crest. The only good thing that this Cadillac did for the company was make their other marginal offerings from that time period look a little better.

Cimarron responds? Yes it does to every bump in the road
and every loose interior panel squeak. When you hit the
gas it responds...sometime next week.
If the Cimarron’s only fault was that it pretty much looked like a Cavalier with cushier seats, that kind of a thing might have been forgiven, because looks are subjective. However, the Cimarron made all of the same squeaks and groans that the Cavalier did. The 1.8 liter pushrod 4 cylinder sounded like it was made by the Singer sewing machine company and not the car manufacturer that claimed to set the world standard for luxury automobiles, even the eventual V6 was nothing to brag about since it was only good for around 110 horsepower. The car came with a 4 speed manual transmission as standard equipment. Really! A 4-speed, what a joke!

The Cimarron was a learning experience for Cadillac or at least you would think that it was. Considering the Catera that Cadillac put to market several years after the Cimarron was much better you would think that they learned something from the Cimarron debacle. The Catera though, was simply a badge engineered Opel Omega from Germany. This makes it seem as if Caddy learned nothing from the Cimarron. Since the Catera, Cadillac has not had small car in the lineup again. Maybe that’s the way it should stay.
Oooo! A pink Caddy! I think I just threw up in my mouth a little!

Tuesday, February 14, 2012

Not Political, Just Stupid

The Chrysler commercial that played during halftime of the Super Bowl has generated a lot of buzz. Many political pundits on the right are saying that it is an ad that endorses President Obama because it talks about how it’s halftime in the Super Bowl but in the grand scheme of things it’s halftime for America, and we are going to come back strong in the second half. The right wingers are saying that the commercial is trying to say that Obama will lead this country towards greatness if he is reelected, and since this is an election year, we are at the half-time of his eight years in office.

The ad talks about the ways that we are going to recover from the economic hard times that have befallen this country. Talking about Detroit and how hard things have been there for the last several years but the people there have not given up. All the while never actually showing much of anything that is in Detroit and the ad also starred Clint Eastwood who doesn’t have anything to do with Detroit. The right also says that the ad is somehow payback for Obama bailing out the U.S. auto industry.

I would submit to you that this ad is not political, it does not try to prop up Obama, and it is not a subtle political campaign ad. I say that the ad is just plain stupid. This ad comes from Chrysler touting the American spirit and how great that is. Chrysler is owned by Fiat, an Italian company. Foreign ownership of this once proud American icon is nothing new however since it was Mercedes Benz from Germany that owned them for 10 years before Fiat did. This same Chrysler Company is the company that the U.S. taxpayers lost 1.8 billion dollars of bailout money on when the Federal Government sold its last remaining shares to Fiat for a big loss.

As with the Chrysler Super Bowl ad from 2011, what makes them think that showing people and places from the dilapidated, one time industrial powerhouse of Detroit will make us want to go out and buy one of their cars. Chrysler lost so much ground by building unreliable cars that Americans don’t want to buy, and losing market share year in and year out, to the point that the City of Detroit fell on its face. Are we to believe now that because Detroit is an economically depressed, and a run-down mess, that this somehow made them start building good cars? Is this supposed to be the result of getting bought out and bailed out by the U.S. government and Fiat? Did the government makes start building good cars, or was it Fiat; maybe it was the rough people that live in Detroit. Maybe they build good cars now because of the rap star Eminem. This makes as much sense as ocean front property in North Dakota.

The new 2013 Dodge Dart is just an Alfa Romeo Giulietta with different
headlights and taillights.
Because Fiat now owns Chrysler they call the shots. Chrysler had already moved a lot of manufacturing to places outside of the U.S. so I think some of that might be to blame for the jobless rate in Detroit. Now with Fiat running the show many new models that are currently planned are actually Fiats that were originally designed for the European market, and are now being adapted to be sold as a Dodge in the U.S. or something like that. I am not saying that this is necessarily a bad thing, it's just disingenuous to act as if Chrysler is there fighting its way back for the sake of the people of the U.S. and the City of Detroit.

I am not trying to tear down Chrysler, in fact I hope that they succeed but this commercial is the biggest non-sequitor that I can remember in advertising for some time. The thing that makes it even crazier is that the ad was about two minutes long and it aired during the Super Bowl. The cost of this ad must have been around 10 million. Maybe they could have used that 10 million to pay back the taxpayers for the money that was lost in bailout.

Tuesday, February 7, 2012

Nasty Gases, and Other Things You Don’t Want to Breathe

What is the stuff that is actually coming out of the tailpipe of your car? Is there really any cause for concern or are those that say the pollution from cars will kill us all just crazy? As with most controversial topics, the truth is usually somewhere in the middle. The stuff that comes out of the tailpipe is formed as part of a simple chemical reaction. We need to have a look at this simple chemistry.

The gasoline that is burned in the engine is made from a combination of hydrogen and carbon. Gasoline typically has a molecular formula somewhere in the neighborhood of C7H16 to C8H18. These are heptane and octane. In order to burn the gasoline we must also have oxygen which is O2. This oxygen is in the atmosphere and is mixed with the air that makes its way into the combustion chamber. The other thing that is in the air is nitrogen which is known as N2. Nitrogen isn’t required to make combustion happen but since it’s there when this chemical reaction is occurring, it will have an impact on the byproducts of the combustion process.

So we have hydrogen, carbon, oxygen, and nitrogen, along with trace amounts of other things that don’t have too much of an impact on the combustion process or the results thereof.  The combustion process is going to rearrange all of these things since that is what happens with a chemical reaction takes place. When we burn the hydrocarbons, we split them apart into the H and the C. Ideally a couple of H’s join up with an O from the O2 to form H2O, and the C’s from the HC’s join with an O2 to form CO2. In a perfect world the only byproducts of combustion would be H2O and CO2. We do not live in a perfect world and according to some people the CO2 that results is something akin to poison but that’s a topic for another day.

Remember we also have nitrogen present during the combustion process and this will lead to a bond with oxygen as well. Nitrogen doesn’t usually stick to anything in a reactionary way, but at high temperatures it will, and it will very easily stick to oxygen since oxygen easily bonds with all sorts of different things. Combustion chamber temperatures that are consistently north of 2500° F will cause a lot of bonding between nitrogen and oxygen. These molecules are referred to as oxides of nitrogen or NOx. The N is for nitrogen, the O is for oxygen, and the x is the variable amount of these atoms that can be found together as a result of the combustion process. Usually the molecules that we are dealing with in this situation are NO, nitric oxide, and NO2, nitrogen dioxide.

Particulate matter is another thing that comes from the tailpipe of cars and trucks. Particulates are small microscopic particles that are usually carbon if they come from the tailpipe. These particulates are very minimal in the exhaust from a gasoline powered car or truck but can be quite substantial from the exhaust pipe of a diesel powered vehicle. When you see black plumes from the exhaust pipe of a diesel powered vehicle, these are particulates, usually referred to as soot. Particulates are usually measured in micrometers or microns. One micron is one millionth of a meter. One human hair is about 70 or 80 microns thick. The particulates that are commonly measured coming from a tailpipe are referred to as PM 10’s for the big ones, and PM 2.5’s for the smaller ones. The numbers in these designations refer to diameter of the particle. 
This picture from the DOE puts PM 2.5's into perspective
Other things that come out of the tailpipe can vary a little from one engine to another. Some of these gases are normal trace gasses that are part of the atmosphere such as argon, and some of them result from trace elements found in the fuel such as sulfur. These trace gases are very minute and not much of a concern. Sulfur can be a problem with diesel engines but this has been taken care of through fuel reformulations that eliminate the sulfur. A fair amount of oxygen also comes out the tailpipe because it did not all get used up in the combustion process.

So the things that come out of the tailpipe of a gasoline powered car that are tracked and monitored in some form or another are HC, CO, NOx, CO2, and O2. An important diagnostic tool used by automotive technicians is the 5 gas analyzer that is made to analyze the exhaust for the content of these 5 gases. Of these the ones that are considered hazardous are HC, CO, and NOx.

Carbon Monoxide

Carbon Monoxide is a problem because it is a powerful asphyxiant. This means that it displaces oxygen in the blood stream. The CO itself does not cause tissue damage but considering that it crowds out the oxygen that is normally carried to all of the parts of the body by the red blood cells; it might as well be poison. Prolonged exposure to CO above a level of 50 ppm will lead to a feeling of general flu-like symptoms. Above 200 parts per million and an extreme headache will result after a few hours. Over 1000 ppm and a person would be dead in a few hours. Over 10,000 ppm and a person would be dead after a few breaths. Understanding that this is not a gas that would be good to have coming out the tailpipe is easy.
Carbon monoxide results from incomplete combustion or partial oxidation of the HC’s found in the fuel. You might say that it is fuel that only burned halfway. CO will be very abundant if the engine management system is dumping too much fuel into the engine, and there is not enough oxygen to properly burn it all. This condition is also associated with an extreme amount of carbon buildup in the combustion chamber. When spark plugs are fouled black, chances are the CO emissions from the tailpipe are very high, engine output is low, and fuel economy is down.

If a vehicle is found to have a high amount of CO in the exhaust then the fuel metering system must be examined. Sometimes the problem might just be something like a bad sensor. If the O2 sensor that the engine computer uses to gain feedback about its performance is giving an incorrect reading to due loss of calibration, the computer may dump more fuel into the engine than it needs too. The computer must maintain the air/fuel ratio at 14.7:1, if it adds more fuel than needed the ratio will go down, and the mixture will be too rich. Something like this could also be caused by a plugged fuel injector that is leaking too much gasoline into the intake manifold. The computer might try to lean out the mixture but the leaking fuel is so abundant that the computer can do nothing to correct the situation.


Hydrocarbons which are sometimes referred to as volatile organic compounds (VOC) are linked to the formation of photochemical smog. HC’s react with UV sunlight to form smog which is full of all sorts of lung irritants and respiratory poisons. This smog formation is very common in dry, sunny, climates where big cities are found. HC emissions result anytime HC based fuels are burned. This includes fuels such as gasoline, diesel, and coal.

Hydrocarbon emissions are simply the result of not being able to burn all of the fuel in the combustion chamber. This usually happens when there is too much oxygen and not enough fuel to go around. This causes the combustion to be so weak that much of the fuel that is there doesn’t even get touched by the combustion event; it’s almost as if the fuel is just getting pumped right through the engine and out the exhaust pipe. HC emissions also result when a car is refueling. When the fuel tank is empty and the pump nozzle is dispensing fuel down the filler neck, the tank is full of fumes that get displaced by the liquid as it fills the tank. These fumes get pushed up and out the filler neck opening. All new vehicles have an onboard vapor recovery system that prevents these fumes from escaping but it can never capture all of these evaporative emissions.

One cause of high HC readings is a lean condition.  As is the case with a rich condition, a lean condition could be caused by a sensor that is giving an incorrect reading. The problem may result from the sensor being bad, or the sensor being acted upon in a false manner. For example, the mass airflow sensor measures the amount of air coming into the engine. This sensor usually uses a small wire that is heated by the computer. As the air rushes past the wire it cools it down. The more abundant the airflow, the more the computer must work to keep the wire heated. When the sensor wire gets coated with dirt or oil as might happen when the air filter is not properly maintained, the dirt acts to insulate the wire and the sensor ends up telling the computer that there is less air coming in than there really is. This causes the computer to inject less fuel into the engine so that there is an air/fuel ratio greater than 14.7:1.

If a car has high HC readings, the most likely culprit is the ignition system. High HC readings most commonly result from a misfire of the ignition system. The ignition system must deliver a spark to each cylinder at just the right time in order to set off the combustion process. If the spark doesn’t get delivered because the spark plug is bad or the ignition coil isn’t working right then a misfire occurs. When this happens the engine stumbles a bit and the air and fuel that were supposed to be burned in the combustion chamber get pumped straight into the exhaust. Many times this will look the same to an emissions analyzer as a lean condition because not only will the HC level be elevated but so will the O2 levels because neither one reacted in the cylinder as it should have. To make matter worse, the O2 sensor in the exhaust will see all of the oxygen and think that the engine is lean so the injectors will just pump even more fuel into the engine making the HC readings at the tailpipe even higher.

If your gas cap has a bad seal HC emissions will result from the expanding fumes leaking out of the tank past the cap seal. Modern cars are smart enough to know if the gas cap is physically compromised, or if you have left it loose. These cars and trucks will illuminate the check engine light in such an event, and some of the newest cars out there will illuminate an indicator to alert the driver that the fuel cap is loose or missing.

Oxides of Nitrogen

Like hydrocarbons, NOx gases react with UV light from the sun to form the components of photochemical smog. One of the worst things that results from this reaction is ground level ozone, or O3. Ozone in the stratosphere is good because it blocks harmful UV rays from the sun and lets the non-harmful rays through, but ozone at ground level is bad because it is a respiratory irritant that can make you sick, especially if you already have respiratory troubles such as asthma.

To form ozone, the NO2 molecule loses one of its O’s and that free O will quickly join with an O2 to form O3. The NO that remains mixes with rain water to form a very weak nitric acid. This is what they call acid rain and it has been known to cause problems in some urban areas because it can be very corrosive.

High NOx emissions are only a problem with some engines; much of this depends on the overall design of the engine. Historically if a car had high NOx emissions the problem may have been improper adjustment of the ignition distributor. Since NOx forms when combustion chamber temperatures are high, overly advanced ignition timing caused by misadjustment of the distributor results in burning the fuel under higher pressure which also means higher temperatures. Engines that have a tendency towards high combustion chamber temperatures will usually have a system that is meant to specifically reduce NOx formation. This is the Exhaust Gas Recirculation system (EGR).

EGR reduces combustion chamber temperatures by circulating inert exhaust gases from the exhaust manifold into the intake manifold. These exhaust gases displace oxygen, and because they are inert, or already spent, they don’t affect the combustion process. With less oxygen in the combustion chamber, the burn will not be as intense and temperatures will go down.

Newer vehicles do not have distributors so there is nothing to be misadjusted and cause an increase in NOx emissions. Most of them do have EGR systems however, so if NOx levels at the tailpipe are too high then the problem is almost guaranteed to be related to a malfunction of the EGR system. Sometimes an overheated engine will produce too much NOx for reasons that are obvious, but if you have an extremely overheated engine you likely have much bigger issues to deal with than high NOx from the tailpipe.

Oxygen, Carbon Dioxide, and Water

None of these gases are pollution. O2 and CO2 are monitored by a 5 gas analyzer because they give clues about the overall efficiency of the combustion in the engine that is being tested. CO2 output should be about 14% and O2 output should be around 1%. If oxygen is higher than that, a lean condition is present. If it is lower than that, then a rich condition is indicated.

Water is the most abundant byproduct of the combustion process. This is very visible when a car is started and driven with very low ambient temperatures. The white plumes that come from the exhaust on a cold morning are the condensation of this water vapor. Many times it is possible to see water dripping from the tailpipe of a car that is idling. This water is also the reason that exhaust systems always seem to rust out eventually. With so much water coming out of that tailpipe it’s amazing they don’t rust out sooner than they do.

Normal Readings

Emissions testing that invovles simulated driving of the vehicle
 Looking at the results of emissions testing in a heavily populated area that requires such testing annually, one might routinely see the following readings on newer cars and trucks: CO 0.00%, HC 0 ppm, and NOx 0ppm. Does this mean that these new cars don’t pollute? No, it just means they are so clean now that the emissions analyzers cannot read that low. Modern cars are very clean compared to what they used to be, but they can probably get even cleaner and will likely continue to do so. In the old days the three nasty gases mentioned above (CO, HC, NOx) were responsible for the major pollution in the air of big cities around the country. While air pollution is still a problem in some places, things are much cleaner than they used to be.

One of the biggest pollutants from vehicles now is particulate matter. As stated previously the exhaust of a gasoline powered car doesn’t contain much in the way of particulates. The particulates that come from cars and trucks now comes from things like the tires wearing down, or normal dust and dirt being kicked up from the road surface as the car passes over it. Cars really are so clean now that pollution from bits of tire is now one of the biggest concerns.

CO2 is and likely will remain the biggest controversies in relation to tailpipe emissions. The issue lies in the fact that many, not all, and maybe not even most, scientists link CO2 emissions to global warming. CO2 is said to be a greenhouse gas and the fact of the matter is that a significant portion of car exhaust is CO2. The problem here is that CO2 is also in the air we exhale as we breathe. So are human beings just living and breathing also contributing to global warming? Some of the extremists on the left would say so. If 14% CO2 from the exhaust pipe causes global warming, why doesn’t anyone address all of the water vapor that comes out of the tailpipe? Water vapor in the atmosphere is such a powerful greenhouse gas that it is almost singlehandedly makes this planet inhabitable. Is 14% CO2 really contributing to global warming more than the 86% water vapor?

No matter what happens with the theory of global warming or climate change, air pollution problems are real, burning fossil fuels has led to sickness and death in the past, emission controls are very important and emissions laws do have a place. The perceived right of one party to spew whatever they want into the air does not trump the literal right of others to breathe air that is untainted. These problems are all local problems that apply to small areas, meaning certain cities or counties, and not entire contents as a whole. Any attempt to push such things onto larger, all-encompassing areas becomes problematic. Cause and effect cannot be proven, so for now we should all keep our vehicles running properly so we don’t pollute.

If your check engine light is on it means that your vehicle is polluting and you should get it fixed as soon as possible. If your vehicle is putting out excessive emissions, it is also likely to be using more gas then it should, and not producing as much power as it ought to be able to produce. Surely those are things that everyone can understand.