Review of Cargraphic Loud exhaust & an audiophile's guide :-) to exhaust auditioning.
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I have a 997.1tt Tip with Fabspeed exhaust installed (don't have any details on the exhaust besides that it says "fabspeed" on it, as it was installed when I purchased the car).
Overall thoughts: I LOVE it. I would call it "medium loud". Actually the thing I like most about it is I do hear some "rumbles and gurgles" even at low speeds / low RPM's. Sometimes I get stuck in 60mins of terrible Chicago traffic and I like to be reminded I am driving a supercar.
1. There is a slight hum / 'drone', which I do not find annoying at all. It isn't that loud relative to the exhaust sound overall. Generally btwn 2krpm and 3krpm is when I hear it I think but not through that entire range.
2. 2k RPM to 3k RPM.
3. Not a problem at all. I don't hear the drone much and when I do hear it, it doesn't sound bad, nor does it overwhelm the rest of the exhaust sounds. Really I sort of think of it like: the exhaust setup gives you maybe 4 or 5 different sounds ... rumble and gurgle at idle or low speeds ... a bit of throat with initial RPM climb... short drone btwn 2krpm and 3krpm... starting to scream (& hear wonderful turbo's spooling) at 4krpm and then an all out scream. I enjoy the whole symphony :-)
Overall thoughts: I LOVE it. I would call it "medium loud". Actually the thing I like most about it is I do hear some "rumbles and gurgles" even at low speeds / low RPM's. Sometimes I get stuck in 60mins of terrible Chicago traffic and I like to be reminded I am driving a supercar.
1. In tiptronic 997.1 Turbo, do you have this same hum? At which rpm?
2. At what rpm do you freeway cruise in your Tiptronic car? Depending on speed I know, but in general, what rpm?
3. Since you can't easily select the gear and therefore select cruising rpm as in a manual car, if the 2400-2800 rpm hum exists, does it present a problem for those with after-market exhausts?
2. At what rpm do you freeway cruise in your Tiptronic car? Depending on speed I know, but in general, what rpm?
3. Since you can't easily select the gear and therefore select cruising rpm as in a manual car, if the 2400-2800 rpm hum exists, does it present a problem for those with after-market exhausts?
2. 2k RPM to 3k RPM.
3. Not a problem at all. I don't hear the drone much and when I do hear it, it doesn't sound bad, nor does it overwhelm the rest of the exhaust sounds. Really I sort of think of it like: the exhaust setup gives you maybe 4 or 5 different sounds ... rumble and gurgle at idle or low speeds ... a bit of throat with initial RPM climb... short drone btwn 2krpm and 3krpm... starting to scream (& hear wonderful turbo's spooling) at 4krpm and then an all out scream. I enjoy the whole symphony :-)
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Don't forget to do the tunnel test; very good especially if you've just had a bad day at work.
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(You might want to also check the following thread for additional info: http://www.rennteam.com/forum/thread...ust/page1.html )
First, my "credential" LOL: I am an all-out nuttier-than-nuts audiophile who cares very much about sound. When I was looking for exhaust systems a while ago, I've had much difficulty when someone waxes poetic about some exhaust system without ever DESCRIBING what it sounds like, so here is my attempt to describe what I hear. I will add some comments on what I have learned about other aspects of exhaust systems (power gain, torque loss, etc.) later. I have listened to many exhaust systems in person so IMHO I have a good frame of reference as to what each of them sounds like. So without further ado: The Cargraphic Loud Exhaust is the first mod installed in my Turbo, about 2 years ago. For anyone curious, the brain/tuner behind the exhaust is Reinhold Schmirler - the RS of RS Tuning, formerly at Ruf and now tunes 911 professional race cars for a living, among other thing. Schmirler has an engine dyno at his facility and I would expect the Cargraphic exhaust's development involves this dyno, a very good thing. Schmirler is not well known in US but is considered to be a top notch tuner in Europe. "Phoenix" based in England is the company that makes the exhaust. So despite of the somewhat odd name "Cargraphic," rest assuredthis is a competently designed exhaust system with an outstanding pedigree.
There are 3 versions of Cargraphic Turbo exhaust, Quiet, Medium, and Loud, and all 3 are available in the US; to be sure you should check with the US importer, Road Sport Supply, a 6speed forum sponsor. They key to remember is this, once windows are up, even the Loud Version (what a silly name, RSS please change it) is not that loud at all. In comparison to other exhausts I've auditioned (many), it has medium loudness. I've been told that in general the trend is that, for US customers, some of those who ask for the more quiet version end up wanting to move to the louder one; the other way around is nearly nonexistent. I've also heard rumor from fairly reliable source that if you are to tune the ECU, the Loud version is the most free-breathing, and therefore the most desirable.
When you move from the stock system to this, you will likely notice that it's a day and night improvement over stock exhaust. It is quite frankly one of the most beloved mods in my car, up there right next to the Bilstein coilover. When I evaluate exhaust, there are 3 parameters I listen for, so here I will compare stock vs. Cargraphic on these 3 parameters:
1. Loudness: I would rate the Cargraphic Loud as high-medium in loudness. Don't let the name fool you, the Loud version of this exhaust is not that loud and about 10% of the times I wish that it is even louder. OF course 10% of the times I wish it *less* loud :-); this is simply the nature of the beast, we don't always want the same thing all the times. For example, the AWE exhaust has similar loudness to this, and the GMG is louder. No right or wrong, just pick what you prefer most here. And below are my rankings of loudness, approximately based mostly on what I heard, and also on what people I think trustworthy have reported. Don't be upset if you disagree please, this is simply my opinion based on the best I could hear, and is subjected to changes any time.
1. GMG
2. A tie between AWE and Cargraphic Loud; BBI would probably be in this group also. Probably.
3. EP2
4. EP1
5. Tubi
2. Frequency balance: Stock sounds whinny, like a hair dryer, with more high frequency. Cargraphic has a low frequency grunt that is fantastic and wonderful to listen too. Plain and simple one of the most important feature of this exhaust system. You hear this most often for example at slight on-throttle, to about 1500 rpm at Stop sign. That's why I sometimes unknowingly act like a juv. delinquent at Stop sign: I rev the engine just to hear it! :-)
At higher rpm, the frequency climbs, until 7000 rpm then it becomes a mechanical scream. If you are in a tunnel, it is deafening, like a race car.
3. Character: Stock is continuous in character, like a Lexus. Cargraphic, especially if you listen from outside, has a spectacular machine gun like staccato. Heard this first time I auditioned this and thought I was in heaven. Inside, like ALL turbo exhaust systems, the sound could never match that of a NA engine. Sorry, just the way it is. I love my Cargraphic but I will be the first to admit that if you want the best interior sound, nothing "turbo" will "crackle" and match the excitement of exhaust systems of GT3, or Lambo, or Ferrari.
4. Hallmark of this system - the deep throat purr LOL: Makes a point to listen for this as you audition exhaust systems because a few other Porsche systems I've listened to seem to lack this low frequency grunt, which gives a sense of power, besides simply sounding d*mn good. Unfortunately until you hear and compare, you won't know what you are missing.
Note that, as in *all* exhaust systems, in-cabin sound is quite different from listening to the car outside, say from the sidewalk with someone else driving the car. The in-cabin sound in general has less of the extreme ends of frequency response and is not as loud. For Cargraphic, the in-cabin sound is very similar to that of GT3 with respect to loudness/freq/character, except it doesn't have as high of a scream associated with the higher RPM climb of the GT3. Bottom line: I would recommend the Cargraphic system without hesitation or reservation over the stock system. It totally changes the driving experience.
Up next, some pointers on exhaust auditioning for those new to this. And lastly, a warning: I am an over-the-top audiophile who still use a tube preamp, so you must take everything I write about audio with a grain of salt.
First, my "credential" LOL: I am an all-out nuttier-than-nuts audiophile who cares very much about sound. When I was looking for exhaust systems a while ago, I've had much difficulty when someone waxes poetic about some exhaust system without ever DESCRIBING what it sounds like, so here is my attempt to describe what I hear. I will add some comments on what I have learned about other aspects of exhaust systems (power gain, torque loss, etc.) later. I have listened to many exhaust systems in person so IMHO I have a good frame of reference as to what each of them sounds like. So without further ado: The Cargraphic Loud Exhaust is the first mod installed in my Turbo, about 2 years ago. For anyone curious, the brain/tuner behind the exhaust is Reinhold Schmirler - the RS of RS Tuning, formerly at Ruf and now tunes 911 professional race cars for a living, among other thing. Schmirler has an engine dyno at his facility and I would expect the Cargraphic exhaust's development involves this dyno, a very good thing. Schmirler is not well known in US but is considered to be a top notch tuner in Europe. "Phoenix" based in England is the company that makes the exhaust. So despite of the somewhat odd name "Cargraphic," rest assuredthis is a competently designed exhaust system with an outstanding pedigree.
There are 3 versions of Cargraphic Turbo exhaust, Quiet, Medium, and Loud, and all 3 are available in the US; to be sure you should check with the US importer, Road Sport Supply, a 6speed forum sponsor. They key to remember is this, once windows are up, even the Loud Version (what a silly name, RSS please change it) is not that loud at all. In comparison to other exhausts I've auditioned (many), it has medium loudness. I've been told that in general the trend is that, for US customers, some of those who ask for the more quiet version end up wanting to move to the louder one; the other way around is nearly nonexistent. I've also heard rumor from fairly reliable source
that if you are to tune the ECU, the Loud version is the most free-breathing, and therefore the most desirable.When you move from the stock system to this, you will likely notice that it's a day and night improvement over stock exhaust. It is quite frankly one of the most beloved mods in my car, up there right next to the Bilstein coilover. When I evaluate exhaust, there are 3 parameters I listen for, so here I will compare stock vs. Cargraphic on these 3 parameters:
1. Loudness: I would rate the Cargraphic Loud as high-medium in loudness. Don't let the name fool you, the Loud version of this exhaust is not that loud and about 10% of the times I wish that it is even louder. OF course 10% of the times I wish it *less* loud :-); this is simply the nature of the beast, we don't always want the same thing all the times. For example, the AWE exhaust has similar loudness to this, and the GMG is louder. No right or wrong, just pick what you prefer most here. And below are my rankings of loudness, approximately based mostly on what I heard, and also on what people I think trustworthy have reported. Don't be upset if you disagree please, this is simply my opinion based on the best I could hear, and is subjected to changes any time.
1. GMG
2. A tie between AWE and Cargraphic Loud; BBI would probably be in this group also. Probably.
3. EP2
4. EP1
5. Tubi
2. Frequency balance: Stock sounds whinny, like a hair dryer, with more high frequency. Cargraphic has a low frequency grunt that is fantastic and wonderful to listen too. Plain and simple one of the most important feature of this exhaust system. You hear this most often for example at slight on-throttle, to about 1500 rpm at Stop sign. That's why I sometimes unknowingly act like a juv. delinquent at Stop sign: I rev the engine just to hear it! :-)
At higher rpm, the frequency climbs, until 7000 rpm then it becomes a mechanical scream. If you are in a tunnel, it is deafening, like a race car.
3. Character: Stock is continuous in character, like a Lexus. Cargraphic, especially if you listen from outside, has a spectacular machine gun like staccato. Heard this first time I auditioned this and thought I was in heaven. Inside, like ALL turbo exhaust systems, the sound could never match that of a NA engine. Sorry, just the way it is. I love my Cargraphic but I will be the first to admit that if you want the best interior sound, nothing "turbo" will "crackle" and match the excitement of exhaust systems of GT3, or Lambo, or Ferrari.
4. Hallmark of this system - the deep throat purr LOL: Makes a point to listen for this as you audition exhaust systems because a few other Porsche systems I've listened to seem to lack this low frequency grunt, which gives a sense of power, besides simply sounding d*mn good. Unfortunately until you hear and compare, you won't know what you are missing.
Note that, as in *all* exhaust systems, in-cabin sound is quite different from listening to the car outside, say from the sidewalk with someone else driving the car. The in-cabin sound in general has less of the extreme ends of frequency response and is not as loud. For Cargraphic, the in-cabin sound is very similar to that of GT3 with respect to loudness/freq/character, except it doesn't have as high of a scream associated with the higher RPM climb of the GT3. Bottom line: I would recommend the Cargraphic system without hesitation or reservation over the stock system. It totally changes the driving experience.
Up next, some pointers on exhaust auditioning for those new to this. And lastly, a warning: I am an over-the-top audiophile who still use a tube preamp, so you must take everything I write about audio with a grain of salt.
I want to install Europipe Stage I in my 07 tt. I have done an extensive online research I have seen very good reviews and comments.
My doubt is that I can´t hear it in person because there is no one in Madrid with this exhaust, Also I trust you when you say that you need to hear it in person.
Based on your incredible experience how do you rate Europipe I ? I am worried because I don´t want something too loud. What do you think ? For instance have you had the opportunity to hear the OEM sport exhaust on a 991S ? How compares to EP I ? Louder ? More or less the same ?
Thanks a lot in advance,
Antonio
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Hi Can,
I want to install Europipe Stage I in my 07 tt. I have done an extensive online research I have seen very good reviews and comments.
My doubt is that I can´t hear it in person because there is no one in Madrid with this exhaust, Also I trust you when you say that you need to hear it in person.
Based on your incredible experience how do you rate Europipe I ? I am worried because I don´t want something too loud. What do you think ? For instance have you had the opportunity to hear the OEM sport exhaust on a 991S ? How compares to EP I ? Louder ? More or less the same ?
I want to install Europipe Stage I in my 07 tt. I have done an extensive online research I have seen very good reviews and comments.
My doubt is that I can´t hear it in person because there is no one in Madrid with this exhaust, Also I trust you when you say that you need to hear it in person.
Based on your incredible experience how do you rate Europipe I ? I am worried because I don´t want something too loud. What do you think ? For instance have you had the opportunity to hear the OEM sport exhaust on a 991S ? How compares to EP I ? Louder ? More or less the same ?
I have driven 991S without sport exhaust, and have driven/listened to 997/997S with and without sport exhaust; the comparison here would be to my Turbo Cargraphic exhaust.
991S without Sport Exhaust: If you ever wonder how sound, or lack thereof, could ruin an otherwise great sports car, drive this car. Good note, much better than stock Turbo, but still, too insulated, too quiet. Some sound was crying and dying to get out of the 991.
997S with Sport Exhaust: Much better than standard, deeper and louder, very nice sounding outside of car. Just not loud enough, especially inside of car.
997 Turbo with Cargraphic: An example of how a great exhaust could totally transform the driving experience, from polite and cute to blunt and menacing (to me anyway LOL). Deeper note, screams on throttle, louder, more muscular - in all aspects, except for conversation-friendliness, it is plain and simple better. I would roll down windows and revs the car just to hear more of the sound. I would expect your experience with EP to be similar to this, with less loudness.
Good luck and have fun. BTW, fans of great exhaust notes should drive a naturally aspirated cars such as Lambo, Ferrari, or GT3 with muffler bypass, etc. The GT3 with muffler-bypass nearly caused me to pass out from the noise ecstasy - my chest was literally vibrating with every jab of the throttle; not exactly neighbor friendly though. If you think any Turbo exhaust is king-of-the-road, you have not heard enough. Sadly the nature of the beast is such that our Turbo could never match the howls and crackles of these naturally aspirated cars, especially as they climb the rpm's. But it's OK, ours has low end torque they can't match.
Last edited by cannga; Aug 18, 2012 at 03:21 AM.
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Some interesting read about the muffler. I couldn't quote the diagram so you might want to visit the site to understand the resonator:
>>>>>>>>>>>>>
http://auto.howstuffworks.com/muffler4.htm
How Can You Cancel Out Sound?
The key thing about sound waves is that the result at your ear is the sum of all the sound waves hitting your ear at that time. If you are listening to a band, even though you may hear several distinct sources of sound, the pressure waves hitting your ear drum all add together, so your ear drum only feels one pressure at any given moment.
Now comes the cool part: It is possible to produce a sound wave that is exactly the opposite of another wave. This is the basis for those noise-canceling headphones you may have seen. Take a look at the figure below. The wave on top and the second wave are both pure tones. If the two waves are in phase, they add up to a wave with the same frequency but twice the amplitude. This is called constructive interference. But, if they are exactly out of phase, they add up to zero. This is called destructive interference. At the time when the first wave is at its maximum pressure, the second wave is at its minimum. If both of these waves hit your ear drum at the same time, you would not hear anything because the two waves always add up to zero.
How sound waves add and subtract
In the next section, we'll see how the muffler is designed to create waves that cause as much destructive interference as possible.
Inside a Muffler
Located inside the muffler is a set of tubes. These tubes are designed to create reflected waves that interfere with each other or cancel each other out. Take a look at the inside of this muffler:<li class="font7 marginVertical3 pagelink">The exhaust gases and the sound waves enter through the center tube. They bounce off the back wall of the muffler and are reflected through a hole into the main body of the muffler. They pass through a set of holes into another chamber, where they turn and go out the last pipe and leave the muffler.
A chamber called a resonator is connected to the first chamber by a hole. The resonator contains a specific volume of air and has a specific length that is calculated to produce a wave that cancels out a certain frequency of sound. How does this happen? Let's take a closer look ...<li class="font7 marginVertical3 pagelink">
<li class="font7 marginVertical3 pagelink">The Resonator
When a wave hits the hole, part of it continues into the chamber and part of it is reflected. The wave travels through the chamber, hits the back wall of the muffler and bounces back out of the hole. The length of this chamber is calculated so that this wave leaves the resonator chamber just after the next wave reflects off the outside of the chamber. Ideally, the high-pressure part of the wave that came from the chamber will line up with the low-pressure part of the wave that was reflected off the outside of the chamber wall, and the two waves will cancel each other out.<li class="font7 marginVertical3 pagelink">The animation below shows how the resonator works in a simplified muffler.<li class="font7 marginVertical3 pagelink">http://auto.howstuffworks.com/muffler4.htm
>>>>>>>>>>>>>
http://auto.howstuffworks.com/muffler4.htm
How Can You Cancel Out Sound?
The key thing about sound waves is that the result at your ear is the sum of all the sound waves hitting your ear at that time. If you are listening to a band, even though you may hear several distinct sources of sound, the pressure waves hitting your ear drum all add together, so your ear drum only feels one pressure at any given moment.
Now comes the cool part: It is possible to produce a sound wave that is exactly the opposite of another wave. This is the basis for those noise-canceling headphones you may have seen. Take a look at the figure below. The wave on top and the second wave are both pure tones. If the two waves are in phase, they add up to a wave with the same frequency but twice the amplitude. This is called constructive interference. But, if they are exactly out of phase, they add up to zero. This is called destructive interference. At the time when the first wave is at its maximum pressure, the second wave is at its minimum. If both of these waves hit your ear drum at the same time, you would not hear anything because the two waves always add up to zero.
How sound waves add and subtract
In the next section, we'll see how the muffler is designed to create waves that cause as much destructive interference as possible.
Inside a Muffler
Located inside the muffler is a set of tubes. These tubes are designed to create reflected waves that interfere with each other or cancel each other out. Take a look at the inside of this muffler:<li class="font7 marginVertical3 pagelink">The exhaust gases and the sound waves enter through the center tube. They bounce off the back wall of the muffler and are reflected through a hole into the main body of the muffler. They pass through a set of holes into another chamber, where they turn and go out the last pipe and leave the muffler.
A chamber called a resonator is connected to the first chamber by a hole. The resonator contains a specific volume of air and has a specific length that is calculated to produce a wave that cancels out a certain frequency of sound. How does this happen? Let's take a closer look ...<li class="font7 marginVertical3 pagelink">
<li class="font7 marginVertical3 pagelink">The Resonator
When a wave hits the hole, part of it continues into the chamber and part of it is reflected. The wave travels through the chamber, hits the back wall of the muffler and bounces back out of the hole. The length of this chamber is calculated so that this wave leaves the resonator chamber just after the next wave reflects off the outside of the chamber. Ideally, the high-pressure part of the wave that came from the chamber will line up with the low-pressure part of the wave that was reflected off the outside of the chamber wall, and the two waves will cancel each other out.<li class="font7 marginVertical3 pagelink">The animation below shows how the resonator works in a simplified muffler.<li class="font7 marginVertical3 pagelink">http://auto.howstuffworks.com/muffler4.htm
Last edited by cannga; Oct 22, 2012 at 08:25 PM.
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Interesting read on O2 sensors. My understanding is that modern cars have 2 oxygen sensors: pre and post catalytic converter. The pre cat sensor feeds its data/signal to the ECU and that in turn regulates "correct" air/fuel ratio in combustion chambers, and the post cat sensor monitors the catalytic converter to make sure it is working. Any pro or expert pls feel free to chime in as needed.
>>>>>>>>>>>>>
http://www.smogtips.com/oxygen_sensor.cfm
Sensor (O2 Sensor)The Oxygen Sensor, also known as the O2 Sensor is the component responsible for delivering exhaust information to a vehicle's emissions computer. Most late model vehicles will be equipped with both a pre-CAT oxygen sensor and a post-CAT oxygen sensor. The O2 sensor sends an electric signal directly in proportion to the oxygen content in your vehicle's exhaust stream. The higher the oxygen content in the exhaust stream, the lower the voltage signal the O2 will produce, and visa-versa. Through this information the emissions computer can determine whether to deliver more or less fuel to the combustion chambers. Late model vehicles are equipped with two oxygen sensors, one before and one after the CAT in order to monitor oxygen content exiting the exhaust manifold and at the same time to ensure the Catalytic Converter/s are functioning properly.
Heated O2 Sensor: The more recent model of the oxygen sensor is the heated oxygen sensor (H2O Sensor). An oxygen sensor's temperature must be around 650F before it will generate a voltage signal. By adding an internal heater to the oxygen sensor, voltage can be generated long before the engine has completely warmed up. Most oxygen sensors in newer cars are of this type.
Location: Oxygen sensors are always located along the exhaust path and before the tailpipe. In vehicles with only a pre-CAT O2 sensor the sensor will be located either directly before the catalytic converter or on the exhaust manifold. In vehicles with both a pre CAT and post CAT oxygen sensor, one sensor will be located directly before the CAT and the other directly after. Vehicles with dual exhaust systems can have up to four oxygen sensors monitoring exhaust streams on both sides of the engine. Dual bank and dual exhaust engines are typically V-6 or V-8 models.
For the Smog Test: Fuel delivery to an engine's combustion chambers are controlled by the vehicle's emissions computer or engine control unit (ECU) and fuel injectors. In order for an engine to pass a smog inspection, fuel delivery must be preciously controlled to produce the least emissions. If the injectors do not present adequate fuel to the combustion chambers, this causes low CO emissions and a lean fuel mixture causing high HC. In a situation where the injectors present too much fuel, this causes high CO emissions and a rich fuel mixture resulting in high HC emissions. The main component responsible for letting the computer know how much fuel is in the exhaust system at any given moment, is the Oxygen Sensor. The Oxygen Sensor sends an electrical signal to the ECU, letting the computer determine exactly how much fuel it should continue to deliver to the combustion chambers. If for any reason the 02 sensor does not send accurate information to the computer or is lazy in sending the correct signal, the fuel delivery program will be altered.
Operation: During normal operation an oxygen sensors voltage should be switching between 0.1 to 1.0 volt at a rate of approximately 50 cycles per minute. An O2 sensor voltage above 0.45 volts is interpreted by the ECM as a rich exhaust, and an O2 sensor voltage signal below 0.45 volts as a lean exhaust. The ECM's responsibility is to keep the oxygen sensor voltage switching between high and low voltage for optimum fuel efficiency, lowest emissions and highest miles per gallon. Usually the first sign of a damaged or defective oxygen sensor is poor fuel economy.
In Case of Failure: The average lifetime of an unheated oxygen sensor is 50,000 miles, and the heated oxygen sensor, 100,000 miles. Needless to say oxygen sensors require periodic replacement. Failure to do so will more then likely cause a smog check failure. 4 out of 10 high CO failed smog checks will be due to a defective, damaged or lazy oxygen sensor. It is probably one of the most underrated emissions components and should be payed much closer attention. Often passing the smog inspection is a simple as installing a new oxygen sensor. We recommended an experienced auto smog or emissions repair mechanic perform the removal, installation and diagnosis of this component.
>>>>>>>>>>>>>
http://www.smogtips.com/oxygen_sensor.cfm
Sensor (O2 Sensor)The Oxygen Sensor, also known as the O2 Sensor is the component responsible for delivering exhaust information to a vehicle's emissions computer. Most late model vehicles will be equipped with both a pre-CAT oxygen sensor and a post-CAT oxygen sensor. The O2 sensor sends an electric signal directly in proportion to the oxygen content in your vehicle's exhaust stream. The higher the oxygen content in the exhaust stream, the lower the voltage signal the O2 will produce, and visa-versa. Through this information the emissions computer can determine whether to deliver more or less fuel to the combustion chambers. Late model vehicles are equipped with two oxygen sensors, one before and one after the CAT in order to monitor oxygen content exiting the exhaust manifold and at the same time to ensure the Catalytic Converter/s are functioning properly.
Heated O2 Sensor: The more recent model of the oxygen sensor is the heated oxygen sensor (H2O Sensor). An oxygen sensor's temperature must be around 650F before it will generate a voltage signal. By adding an internal heater to the oxygen sensor, voltage can be generated long before the engine has completely warmed up. Most oxygen sensors in newer cars are of this type.
Location: Oxygen sensors are always located along the exhaust path and before the tailpipe. In vehicles with only a pre-CAT O2 sensor the sensor will be located either directly before the catalytic converter or on the exhaust manifold. In vehicles with both a pre CAT and post CAT oxygen sensor, one sensor will be located directly before the CAT and the other directly after. Vehicles with dual exhaust systems can have up to four oxygen sensors monitoring exhaust streams on both sides of the engine. Dual bank and dual exhaust engines are typically V-6 or V-8 models.
For the Smog Test: Fuel delivery to an engine's combustion chambers are controlled by the vehicle's emissions computer or engine control unit (ECU) and fuel injectors. In order for an engine to pass a smog inspection, fuel delivery must be preciously controlled to produce the least emissions. If the injectors do not present adequate fuel to the combustion chambers, this causes low CO emissions and a lean fuel mixture causing high HC. In a situation where the injectors present too much fuel, this causes high CO emissions and a rich fuel mixture resulting in high HC emissions. The main component responsible for letting the computer know how much fuel is in the exhaust system at any given moment, is the Oxygen Sensor. The Oxygen Sensor sends an electrical signal to the ECU, letting the computer determine exactly how much fuel it should continue to deliver to the combustion chambers. If for any reason the 02 sensor does not send accurate information to the computer or is lazy in sending the correct signal, the fuel delivery program will be altered.
Operation: During normal operation an oxygen sensors voltage should be switching between 0.1 to 1.0 volt at a rate of approximately 50 cycles per minute. An O2 sensor voltage above 0.45 volts is interpreted by the ECM as a rich exhaust, and an O2 sensor voltage signal below 0.45 volts as a lean exhaust. The ECM's responsibility is to keep the oxygen sensor voltage switching between high and low voltage for optimum fuel efficiency, lowest emissions and highest miles per gallon. Usually the first sign of a damaged or defective oxygen sensor is poor fuel economy.
In Case of Failure: The average lifetime of an unheated oxygen sensor is 50,000 miles, and the heated oxygen sensor, 100,000 miles. Needless to say oxygen sensors require periodic replacement. Failure to do so will more then likely cause a smog check failure. 4 out of 10 high CO failed smog checks will be due to a defective, damaged or lazy oxygen sensor. It is probably one of the most underrated emissions components and should be payed much closer attention. Often passing the smog inspection is a simple as installing a new oxygen sensor. We recommended an experienced auto smog or emissions repair mechanic perform the removal, installation and diagnosis of this component.
Last edited by cannga; Oct 23, 2012 at 08:14 PM.
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Here are some of my observations of the loud cargraphic exhaust:
- much better than stock, makes the car seem more exotic
- has some drone in 6th gear at 65mph, 5th gear much less drone
- is much louder outside the car and does turn heads, even trundling about in a parking lot
- at WOT there is a point where the sound becomes much louder and takes on a "blatty" quality, I suspect this is at max boost when excess exhaust flow bypasses the turbos. For me, this tone is a bit too loud and from what I read the EP might be a better, stealthier choice for me.
- much better than stock, makes the car seem more exotic
- has some drone in 6th gear at 65mph, 5th gear much less drone
- is much louder outside the car and does turn heads, even trundling about in a parking lot
- at WOT there is a point where the sound becomes much louder and takes on a "blatty" quality, I suspect this is at max boost when excess exhaust flow bypasses the turbos. For me, this tone is a bit too loud and from what I read the EP might be a better, stealthier choice for me.
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Here are some of my observations of the loud cargraphic exhaust:
- much better than stock, makes the car seem more exotic
- has some drone in 6th gear at 65mph, 5th gear much less drone
- is much louder outside the car and does turn heads, even trundling about in a parking lot
- at WOT there is a point where the sound becomes much louder and takes on a "blatty" quality, I suspect this is at max boost when excess exhaust flow bypasses the turbos. For me, this tone is a bit too loud and from what I read the EP might be a better, stealthier choice for me.
- much better than stock, makes the car seem more exotic
- has some drone in 6th gear at 65mph, 5th gear much less drone
- is much louder outside the car and does turn heads, even trundling about in a parking lot
- at WOT there is a point where the sound becomes much louder and takes on a "blatty" quality, I suspect this is at max boost when excess exhaust flow bypasses the turbos. For me, this tone is a bit too loud and from what I read the EP might be a better, stealthier choice for me.
When I added EVOMSit Stage 2 ECU tune to my Turbo with Cargraphic a few years ago, the Cargraphic's exhaust became unbearably loud, so loud that I would have a headache every time I drove the car. I love the tune otherwise but had to return it (the EVOMS people was very nice about this; I have no complaint whatsoever). IMHO this was neither the exhaust's, or the tune's, fault - it was merely a unfortunate combination LOL.I discussed this on the first page of this thread, a topic that's very rarely talked about: other components in your car affect the sound of the exhaust, in particular the ECU tune. ALL ECU tunes change exhaust sound, some more than others, a lot more, at least based on the 2 that I tried. In a high power weekend car it is no problem, but for a daily driver, this is a crticical issue. I switched the tune and have been in heaven ever since.
Last edited by cannga; Oct 24, 2012 at 10:58 AM.
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I do have an EVOMSit tune, not sure of the "stage" but most likely stage 1. As another data point, at one time the car had bad plugs, poor throttle response, and I believe the ECU went into some kind of protection state. Then the exhaust was extremely loud. After new plugs and reflash by Sharkwerks, the car runs great and the exhaust noise is much subdued, but still sounds a bit "blatty" at WOT.
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I do have an EVOMSit tune, not sure of the "stage" but most likely stage 1. As another data point, at one time the car had bad plugs, poor throttle response, and I believe the ECU went into some kind of protection state. Then the exhaust was extremely loud. After new plugs and reflash by Sharkwerks, the car runs great and the exhaust noise is much subdued, but still sounds a bit "blatty" at WOT.
. Anytime I hear an unusual review on any exhaust - odd noise, odd drone, odd CEL that no one else reports - my suspicion has always been *what else is on this car*. More specifically, what tune is on this car.Anyway, what's odd is in my car I had a different problem: with the EVOMSit tune added, the car was not just loud, but extremely loud, and sounded high strung, stressful at idle, much like a diesel truck. No one else had talked about the following either but I found out that EVOMS raised the idle RPM by a couple hundreds RPM, regardless of what mode, and this added to the loudness problem at idle. I got a headache every time I drove the car so we decided to remove the EVOMS tune. Immediately, the noise problem disappeared. In retrospect, I am glad for EVOMS's generous return policy that allowed me to switch to GIAC, which in my car has no noise problem whatsoever. I found it amazing that the 2 tunes, EVOMS and GIAC, sound so differently (and drive so differently) from each other.
OT: Just curious - when your car had the above problems, did it have the EVOMS tune in or was it stock? Was there a problem with the original tune? Otherwise, why did they have to re-flash? Did they tell you what was changed in the re-flash?
Last edited by cannga; Oct 25, 2012 at 09:05 AM.
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5 year "anniversary." (Wow has time flown by that quickly? Have I gotten 5 years older just like that, a blink of an eye? :-))
Today I realize that this exhaust has been in my car for 5 years and so, time for an update. And the update is that, knock on woods, no problem so far. No CEL, no problem with the cat, and externally everything looks ok. At $5000, I really shouldn't be surprised that everything is perfect, but if you are into the mod game, you know what I mean. "Enter at your own risk" LOL. Even some stock components of the car have given me a few huge headaches lately (hint: !@#$%^&* coolant leak) so I remain thankful when things are ok.
My only complaint remains the high cost of entry, albeit a mild complaint because the spectacular sound of this exhaust does completely change the driving experience. And of course the reduction in back pressure is critical to my ECU tune. The stock sound of the 997.1 Turbo, which sounds like either a louder Lexus or a hairdryer, along with its soft suspension, remain the two weakest aspects of the car for me (YMMV), so this remains a highest recommendation!
Today I realize that this exhaust has been in my car for 5 years and so, time for an update. And the update is that, knock on woods, no problem so far. No CEL, no problem with the cat, and externally everything looks ok. At $5000, I really shouldn't be surprised that everything is perfect, but if you are into the mod game, you know what I mean. "Enter at your own risk" LOL. Even some stock components of the car have given me a few huge headaches lately (hint: !@#$%^&* coolant leak) so I remain thankful when things are ok.
My only complaint remains the high cost of entry, albeit a mild complaint because the spectacular sound of this exhaust does completely change the driving experience. And of course the reduction in back pressure is critical to my ECU tune. The stock sound of the 997.1 Turbo, which sounds like either a louder Lexus or a hairdryer, along with its soft suspension, remain the two weakest aspects of the car for me (YMMV), so this remains a highest recommendation!
Last edited by cannga; Mar 31, 2013 at 02:07 PM.
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I can't agree more, Can ... I have (I guess?) 4 years on my 2009 Cargraphic Loud and think it's the best thing I've added to the car.
The B&M sport shifter is keen, too. And, the satin black HREs and new skins are right up there as well.
The stock exhaust sounded like a Hoover vacuum. What a disappointment. But, the Cargraphic is just wundermuss !
I still have the car and may keep it when the new Turbo comes out. I'm getting price sensitive these days. Plus, I love this car ! And, the 991 is just OK in my book. Some things I like about the car ... others, not so much.
The B&M sport shifter is keen, too. And, the satin black HREs and new skins are right up there as well.
The stock exhaust sounded like a Hoover vacuum. What a disappointment. But, the Cargraphic is just wundermuss !
I still have the car and may keep it when the new Turbo comes out. I'm getting price sensitive these days. Plus, I love this car ! And, the 991 is just OK in my book. Some things I like about the car ... others, not so much.
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I have the cargraphic exhaust on my car and enjoy the exhaust note. Just failed OBD II diagnostics smog check. Secondary Air System Not Ready and Oxygen Sensor not ready. Car was warmed up and passed the Idle Emission Test. Vehicle did not pass the OBD systime check because its OBD system was not ready to test. Exhaust has the 200 cell cats.
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I have the cargraphic exhaust on my car and enjoy the exhaust note. Just failed OBD II diagnostics smog check. Secondary Air System Not Ready and Oxygen Sensor not ready. Car was warmed up and passed the Idle Emission Test. Vehicle did not pass the OBD systime check because its OBD system was not ready to test. Exhaust has the 200 cell cats.
Re. Secondary Air System Not Ready: Again while anything, including exhaust, is possible cause, this is not a common exhaust related trigger to best of my knowledge. This is a function where air is injected into the exhaust path (header, etc.) to assist with warming up and efficiency of the catalyst (The extra air/oxygen assists with catalysis of unburned hydrocarbons and carbon monoxide.).
Although I don't know the cause, I would *not* be surprised if this alarm is also related post cat O2 sensor, and possible the tune or other mods/problems you might have had in the car previously, and not necessarily the exhaust itself.
BTW, did you drive the car a certain amount of time before the smog check? In certain cars, there is an elaborate pattern of driving (at various speed, time, rpm, etc.) to turn this off - google to find out. I do not know if this is the problem here though.
The most common exhaust related trigger is from catalyst's damage or inefficiency, by any number of reasons, including ECU tune, oil and other contaminants damaging the cat, wear and tear on the cat. What happens is that in a properly functional system, the post cat/downstream O2 sensor (which should show low level of oxygen) is compared against the pre cat/upstream O2 sensor (which should should show high level of oxygen), when there is not enough difference of O2 levels between these 2 sensors, i.e. when the catalyst is not cleaning and therefore O2 levels are not reduced in post cat sensor, the alarm is triggered.
As mentioned different situations would trigger this, among the more common ones: a. catalyst damage by itself or by after-market ECU tune, b. ECU tuning running too rich, or c. the after-market catalyst is not as efficient as stock (nothing wrong with "c" per se, it *could* be part of the territory when you decrease the catalyst density/cpsi from 600 to 200). If it is c, the way around this is the cheater plug (google spark plug non fouler), which cheats by physically distancing the post cat O2 sensor from exhaust stream and should take no more than 1/2 hour to install by pro's.
These alarms could be such a headache. What a bummer and sorry to hear this. Please report what you find and what solutions have been proposed.
Last edited by cannga; Apr 1, 2013 at 05:03 PM.