Drew Dowdell

Lesser Known Tech: The In and Out of In and Out - EGR Explained Today we begin a new series of article on lesser known technology. Many of us gear heads hear of different technologies in vehicles and have a general understanding of why they exist, but sometimes there are things that don't generate much thought because...well.. they seem to always have been there. These articles are to help you understand the background of the technology.... the "how?" and the "why?" that are more than just one or two word answers. In this, our first article, we cover EGR. Most people even vaguely interested in automobiles know what EGR means, but just in case you're not one of those people, EGR stands for Exhaust Gas Recirculation. EGR is the process of returning some of the hot exhaust gas leaving the cylinder chamber and returning it back into the intake stream. Simple right? Yes, but why would you want to do that? IN: EGR was introduced in the 1970s as an emissions control measure. The initial systems were simply on/off vacuum switches depending on the load of the engine. Early systems were lambasted (properly I might add) for robbing engines of performance and causing reliability issues. The maze of rubber hoses found in late 70s through late 80s cars is mostly attributable to the addition of pollution controls. When a strong intake manifold vacuum was pulled (the less the throttle was opened i.e. you took your foot off the gas) the EGR valve opens to let exhaust gases into the intake manifold. As more throttle is applied, vacuum drops and the EGR valve closes. That explains the basics behind "how?", but still doesn't explain the "why?". So why would you want to send exhaust back into the intake? I asked resident powertrain expert Dwightlooi to help explain. EGR enables much less fuel to be burned during low load situations such as when idling or cruising at a constant speed. When power is not needed, the engine typically only needs to burn a only very small amount of fuel. The problem is that very little fuel with a lot of fresh air means a very lean mixture -- simply: a lot of air, not much fuel. A state known as "running lean". Lean burning increases combustion temperatures, and more relevantly, increases the production of Nitrous Oxide, Nitrogen Monoxide, Nitrogen Dioxide,Nitrate Free Radicals, among others, which are considered smog agents. High cylinder temperatures increase the possibility of premature detonation (pinging/knocking). By feeding exhaust back into the intake, you are reducing the oxygen content of the intake charge. Therefore, even though the metered fuel amount doesn't change and the volume of gases drawn into the cylinders doesn't change, the fuel-to-oxygen ratio is now not as lean. This allows the engine to use less fuel without getting too hot and/or make too much pollution. As EGR systems became more sophisticated, they began to actually contribute to the fuel economy performance of the engine rather than detract as early systems did. By introducing inert exhaust gas into the intake manifold at low throttle, it allow for an increase in manifold pressure at a given power output. Increased manifold pressure equals reduced pumping losses (the effort the engine puts into sucking air in) equals greater efficiency. So what happens when an EGR valve fails? It depends if it's stuck open or stuck closed. An EGR valve stuck in the open position will rob an engine of power during acceleration. In worst case scenarios, it will cause stumbling and hesitation under part throttle. An EGR valve stuck in the closed position will cause a rough idle or stalling at idle. Under acceleration or at cruising speeds it can cause pinging an knocking. OUT: But even after 30 years of technological advancement to reduce exhaust pollution and increase fuel economy, the EGR valve itself is slowly going the way of the Dodo. The reason? Variable Valve Timing. Dwightlooi continues: Engines with VVT can dial in huge amounts of valve overlap in the same conditions as you would open an EGR valve. By having both the intake and exhaust valve open at same time you allow exhaust gases to backflow into the cylinder through the exhaust valves even as the intake air is being drawn in. The effect is the same an EGR valve would have accomplished, except you are doing it directly through the exhaust valves instead of feeding gases from the manifold to the intake. It is more precise and no additional hardware over the existing VVT system is needed. By removing the older EGR valves and designing similar functionality into the VVT system, automobile manufacturers are removing a point of failure in engines while continuing to provide the pollution control and fuel economy benefits the older system gave. I hope you enjoy this series and if you have any suggestions for topics in future articles, please PM them to me.

Did you burp your baby?

Tax cuts can't stimulate spending when we still have all of this debt....both public and private.

The confusion is with where you are measuring, not what you are measuring. Everyone's natural tendency is to measure what you put in the car to determine if it's a hybrid..... but a car is more about the motive power. And in the Volt, the motive power comes from the electric motors. We don't call Flex-Fuel vehicles hybrids just because they can run two different fuels do we?

I think this is a transition vehicle to get Chrysler to the actual 200. The Sebring is so bad, it won't make it 2 more years.

Thanks Gizhost, and welcome back. You should check out the other article I wrote aboutjournalists being irresponsible about this Volt reporting

Halloween Photohunt: Find the meanest, scariest, automotive face Win yourself a $25 Amazon gift card. Follow the link for rules and entry instructions. Cheers and Gears Photohunt Challenge: Meanest, Scariest, Automotive face

I'm not entering the contest myself. It's got to be a real car with real graphics...... if it doesn't have flames coming out of the headlights, you can't paint them in later with photoshop.

Photohunt: Meanest, Scariest automotive face We haven't had a contest in a while. In celebration of Halloween: Do your best to find the scariest, meanest automotive face, if chosen the winner, you'll receive a $25 Amazon gift card. Contest Rules: 1. One entry per user.... choose wisely. 2. Kit vehicles and custom vehicles are welcome.... but it has to be a real, physical, life size car. No scale models or CGI. 3. You need not be the photographer, however, if the picture is owned by another member of C&G, you cannot use it. 4. ENTRIES MUST BE UPLOADED TO C&G USING THE ATTACH FILES FUNCTION WHEN POSTING. ENTRIES FROM HOT LINKED IMAGES WILL BE DISQUALIFIED. 5. Entries must be at least 640x480 in size. 6. You can't use "Christine". I already did. Voting begins Friday, October 29th at 8pm eastern. Have your entry in by then. Voting will end Sunday, October 31st at midnight.

So wait... I.R.S. makes your car handle well automatically? I've got I.R.S. in the Toronado..... I should be able to take that new Jetta in an autocross right? right?

What are these based on.... and more importantly, can they make me a Roadmaster version?

I look forward to test driving the turbo

I'm not worked up over the rear suspension. Nearly any suspension type can be made to perform with the proper tuning...... Or did the Cobalt SS have a secretly installed I.R.S. when it took the title of fastest FWD car around the Nürburgring? It's the interior styling/materials and exterior blandness that bother me.

How much did it cost?

What about Japan's unwillingness to deleverage that we are duplicating? No one is willing to take the haircut... so everyone will end up getting one, and that will depress spending for a loooong time.

And every time I've bought a cheaper imitation, I've been sorely disappointed.

I'm still curious how we aren't like Japan.

Older vehicles almost always leak something... I fully expect that I'll need to do the valve cover gaskets this winter after I've switched the car now to full synthetic..... but this is a 30 year old car that I'm trying to preserve. If it needs gaskets... it'll get gaskets.

Multiple accounts are not allowed. Here's your B-day gift.

Oh I don't even agree that all of GM's products are fat.... some of the recent ones are, but only if you compare only price and not size to it's competition. SMK's favorite subject is how "fat" the CTS is compared to the 3-series..... well duh... the 5-series is "fat" compared to the 3-series too. The CTS is within a 10th of an inch of the 5-series in nearly every dimension and is within 70lbs - 150lbs in weight depending on equipment. The Traverse is rather portly if you're comparing it to the Pilot, but look at the size differences between the two. It really takes a "special" kind of student to expect a mid-size car to weigh the same as a large compact.

And while kudos should go to GM for engineering their cars to overcome the laws of physics while having such a weight penalty, imagine what they would be able to do with vehicles that weigh 300-500lbs less. The Camaro and Mustang run so close to each other in ability that most differences are mitigated by driver skill.... now imagine a Camaro with the Mustang's lighter weight. As I said, warranty is what you sell on when you have nothing else going for you. Up until very recently, both Hyundai and Kia were near the back of the pack of any comparison test they were in and their reliability and quality perceptions were the worst of just about anyone. There was no compelling reason to buy a Hyundai/Kia other than Low Cost + Warranty. Now that they've equaled or exceeded their competition in the actual product, I expect the warranty to go first and costs to rise second. Why? Because once the perceptions have changed to be more positive (which there is every sign that's happening already) Hyundai can make more profit on the same product. Hyundai is really aiming for Toyota's perception position they held in 2002. Once they can get people to buy a Hyundai regardless of warranty, looks, or actual reliability (as opposed to perceived) they will have succeeded and the warranty will be toast.

Man... look at that blip there in 1980 and then a constant sinking feeling ever since..... it's almost as if some large even happened in 1980 that changed the way our economic system was organized. Once upon a cold November, back in `80, you'll remember, Came to pass a great election, with a wondrous change in store; By a landslide, one was winning, promising a new beginning; Tall and proud, he stood there, grinning, like so many times before; Who was he, this cool one, grinning, like so many times before? 'Twas The Reagan, nothing more. Once he was inaugurated, Reaganomics he created, Promising a balanced budget, like we had in days of yore; "Though," he said, "our debt is growing, and a bundle we are owing, "I'll cut taxes, 'cause I'm knowing this will save us bucks galore;" "Please explain," a newsman asked, "how will this save us bucks galore?" Quoth The Reagan, "Less is more." Pushing for defense, he pleaded, brand-new missiles would be needed: "That's the only way," he said, "to keep the country out of war;" "True," he said, "they're not required, and they're not meant to be fired; "In five years they'll be retired--still we must build hundreds more;" "Tell us why," a newsman asked, "we must be building hundreds more?" Quoth The Reagan, "Jobs galore." Was he real or from a movie? "Make my day" sure sounded groovy, Standing up to Congress or the rebels in El Salvador; Flicks like "Rambo" he promoted (sev'ral times, it should be noted); Once John Wayne he even quoted, when Kaddafi threatened war; "Does this mean," a newsman asked, "we're heading toward a Mid-East war?" Quoth The Reagan, "Hit the shore." During times he wasn't dozing, many plans he was proposing, Dealing with the deficit, which he no longer could ignore; "Cuts," he said, "I'm recommending, pending our ascending spending, "With attending trends suspending, then extending as before." "Does this mean," a newsman asked, "a balanced budget like before?" Quoth The Reagan, "Nevermore!"