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I have the cete device and it IS able to perform a cold start. What you need to do is press the power button twice without having your foot on the gas. The first press will power the car on, and the second press will illuminate the driving mode knob. Select sport + and then press the power button a third time with the gas pedal pressed. This will perform the cold start with the valves open and it will sound much louder. I have a 2019 GT for reference.
It's basically the same as the renntech EVM, minus the remote control, for half the price. If you search it here, you can find some reviews. Here's the link to the item. I had to use google's translate feature to place my order. https://www.active-sound.eu/en/merce...-valve-control
Members,
Still a bit confused. I know, I know, this is a never-ending discussion on the forum.
1) What do the CETE / Renn EVM do exactly? I realize they both 'fully' open the (2) valves... but what does that mean?
2) Removing the 2nd Cats, what exactly does this do?
What are the different effects for both 1) & 2).
Lastly, in the discussion above, mentions the 'pops & crackles' are only heard in S+. I only drive in R and hear the pops & crackles when letting off the gas (above 4,500RPM) and/or downshifting.
Members,
Still a bit confused. I know, I know, this is a never-ending discussion on the forum.
1) What do the CETE / Renn EVM do exactly? I realize they both 'fully' open the (2) valves... but what does that mean?
2) Removing the 2nd Cats, what exactly does this do?
What are the different effects for both 1) & 2).
Lastly, in the discussion above, mentions the 'pops & crackles' are only heard in S+. I only drive in R and hear the pops & crackles when letting off the gas (above 4,500RPM) and/or downshifting.
Pops and Crackles: only in S+ and R with a stock ECU Mapping. The car doesnt do this kind of mapping of exhaust gas in the other settings. Valves: stock values dont open the valves fully to keep noise emissions from being a problem for Mercedes. So 'open' means more like flap is 75% open. Cete and Renntech remap the car to open 100% Secondary Cats: not all cars have em. If you do its going to contribute to noise suppression. I removed them on a 2018 GTC I had. It was minor in its effect compared to the EVM module.
Thank you Skilly, yes, that does clear up some of my confusion, what does what and why.
May I ask, are you planning to remove the 2nd Cats on your Pro.?
Thank you Skilly, yes, that does clear up some of my confusion, what does what and why.
May I ask, are you planning to remove the 2nd Cats on your Pro.?
Im not. I have a stage 1 renntech and its enough. If I go deeper it will be removing the cats all together and doing a stage 2.
If you go down that path, my recommendation is don't go the cheap way and cut your cats out. Do it right and spend the money to have them removed in 1 piece. Your next owner will thank you...and you will be happy in case you need to bring it back to stock - OEM cats arent cheap or readily available in the used space (unless they are in 2 pieces...lol).
Valves: stock values dont open the valves fully to keep noise emissions from being a problem for Mercedes. So 'open' means more like flap is 75% open. Cete and Renntech remap the car to open 100%.
Not on 2018 GTR's as me and another member has confirmed besides cold start and comfort warm start the Renntech/ASR module does nothing.
Not on 2018 GTR's as me and another member has confirmed besides cold start and comfort warm start the Renntech/ASR module does nothing.
Are you saying that the 18 GTR (GTC will be the same) has the valves fully open when you select the button or move to S+ and R? Not clear what you are saying. I have experience with an 18 GTC (same set up as GTR) and a 2020 GTR Pro so want to understand before I comment.
My experience is with the Cete module, which because of how it integrates, its my preference. It has a material change in valve position for the open setting. Its downside is it takes away cold start and doesn't offer a persistent setting like the ASR/Renntech set up does.
Pops and Crackles: only in S+ and R with a stock ECU Mapping. The car doesnt do this kind of mapping of exhaust gas in the other settings. Valves: stock values dont open the valves fully to keep noise emissions from being a problem for Mercedes. So 'open' means more like flap is 75% open. Cete and Renntech remap the car to open 100% Secondary Cats: not all cars have em. If you do its going to contribute to noise suppression. I removed them on a 2018 GTC I had. It was minor in its effect compared to the EVM module.
Originally Posted by Skilly
Are you saying that the 18 GTR (GTC will be the same) has the valves fully open when you select the button or move to S+ and R? Not clear what you are saying. I have experience with an 18 GTC (same set up as GTR) and a 2020 GTR Pro so want to understand before I comment.
My experience is with the Cete module, which because of how it integrates, its my preference. It has a material change in valve position for the open setting. Its downside is it takes away cold start and doesn't offer a persistent setting like the ASR/Renntech set up does.
Yes if the car is warmed up and you switch to S+ or R the Modules do nothing.
Here is a quick video of how the renntech/ASR module changed my startup. Car sounds amazing on cold start but I think the valve mod really shows itself on warm start. Big difference between the renntech/ASR and Cete is the Renntech/ASR keeps your flaps always open after turning off/on the car. The Cete functions like the stock and closes the valve after turning the car off. To get it open prior to startup you have to turn on the car with foot off the gas to get the electronics on and press the exhaust switch to open the valve and then start the engine. I would think there is less wear/tear and risk for failure with the valves not constantly opening and closing every time the car is turned on/off.
start of video: warm start stock valve position
0:26 valves opened with module
0:42 warm start with valves open with module
1:04 valves returned to stock position
1:12 valves open with module
To me there is also a huge difference in the daily driving. The car sounds way deeper and grumbly without being too loud at normal driving speeds. I’m guessing anyone who installed a module and doesn’t see this result either has a defective module or didn’t install it correctly. The ASR/Renntech module keeps the valves open all the time and I never have to touch the exhaust button.
Here is a quick video of how the renntech/ASR module changed my startup. Car sounds amazing on cold start but I think the valve mod really shows itself on warm start. Big difference between the renntech/ASR and Cete is the Renntech/ASR keeps your flaps always open after turning off/on the car. The Cete functions like the stock and closes the valve after turning the car off. To get it open prior to startup you have to turn on the car with foot off the gas to get the electronics on and press the exhaust switch to open the valve and then start the engine. I would think there is less wear/tear and risk for failure with the valves not constantly opening and closing every time the car is turned on/off.
start of video: warm start stock valve position
0:26 valves opened with module
0:42 warm start with valves open with module
1:04 valves returned to stock position
1:12 valves open with module
To me there is also a huge difference in the daily driving. The car sounds way deeper and grumbly without being too loud at normal driving speeds. I’m guessing anyone who installed a module and doesn’t see this result either has a defective module or didn’t install it correctly. The ASR/Renntech module keeps the valves open all the time and I never have to touch the exhaust button.
The ASR/RT is a complete bypass of the stock system. Your exhaust button and moving through the driving modes doesn't do anything. It's just the remote that will turn the exhausts flaps open/close. Some people have programmed one of the homelink buttons to act as the remote so they dont have to have that at the ready to make a change.
there are plus and minus options for each. For me it felt a little JV to have it act like a bypass so I opted for Cete because you wouldn't even know its there - everything operates as designed...except for the cold start.
As they say, variety is the spice of life. In this case two options that get you there in different ways.
Yes if the car is warmed up and you switch to S+ or R the Modules do nothing.
For what it's worth, the ASR/RT mod bypasses the stock system. So moving through the drive modes wouldn't have an effect. It would be working per the design.
That said, your remote switching on/off should have a very audible difference. If it doesn't, something is wrong with your module, the installation, or the valves.
Is keeping the valves open all the time (like with the Renntech module) bad for the car in any way? Don't the flaps stay closed to build back pressure or something?
I swore I've seen coders who say they can code the exhaust flaps open......am I assuming this really means they are only coding them to what Mercedes considers open (which is only 75% open) and not CETE/Renntech's 100% open?
Is keeping the valves open all the time (like with the Renntech module) bad for the car in any way? Don't the flaps stay closed to build back pressure or something?
I swore I've seen coders who say they can code the exhaust flaps open......am I assuming this really means they are only coding them to what Mercedes considers open (which is only 75% open) and not CETE/Renntech's 100% open?
Back pressure is good for NA engines not much effect on FI engines.
Thought I would jump back in here. Some of the ideas how these flaps work and how the interventions of the Cete/Renntech devices function are getting a little wayward.
Starting from the end, the exhaust flaps return to a "home" position at the end of every ignition cycle. This is a must even with the intervention devices because at startup, the flaps MUST go through a diagnostics startup test otherwise DTCs will be set. There are a series of P-xxxxxx (powertrain faults) assigned to both startup diagnostics and simple operating functions and controlled through the ECU (N3/10). I'll list the codes at the end.
Tuners can go through a data table with hack software and manually "uncheck" operating DTCs so the ECU simply quits reporting them. I've done this numerous times in tunes. However, the diagnostics software is hard code that is inaccessible. Tuners are always doing workarounds to this and the workarounds are always clugey. Long story short, the diagnostics have to run and these devices bypass the operating functions (open/close/partially open) by sending full voltage to the flap motors, but not before the diagnostics run on every startup cycle. If there is doubt this happens, look at the harnesses supplied with the devices. If it were a simple matter of supplying full voltage to the flaps there would only need to be two wires - a ground and an ignition switchable voltage feed.
The other important part of the level of sophistication - both the Cete and the Renntech devices are bypassing the diagnostics (and allowing them to happen) via a splice into the controller area network (CANBUS). If this didn't happen, the flaps would fail at diagnostics. Once diagnostics pass then full voltage is sent to the flap motors keeping them 100% open. Even though the ECU will send varying voltages to the flap motors during various operating cycles (different RPMs, different selectable performance modes, etc.) there are no more functional tests other than opens, shorts, sticking flaps (via turbo pressure sensor inputs that are out of expected values at performance RPMs).
So, a couple of ideas that are not true:
The flaps are not kept open after ignition shutdown. The voltage needed to do that alone would kill a battery before morning.
The intervention is not simply a +v and ground bypass.
The flaps open 100%, at times, with no intervention, but those moments are in certain selectable settings, RPMs ECTs and ETC positions. They are not limited to only 75%, but when they are 100% open, so many other sounds are happening the driver isn't noticing more exhaust sound.
Here are the codes I am aware that are assigned to the exhaust flaps. Some are operating and others are startup diagnostics (exhaust flap 2 is the right side flap):
Last edited by Acta_Non_Verba; 09-15-2022 at 08:44 AM.
The actuators are not simple open - close drives. They are PWM-controlled actuators with self-diagnosis. These consume almost no energy in idle mode. The flaps are moved by a motor via a self-locking gear from 0 - 90 degrees.
Researched but unchecked:
The actuators carry out a self-diagnosis each time they are started (ignition on). i.e. they drive automatically from 0 -90 degrees (stop to stop) If the self-diagnosis is positive, the variable PWM values supplied by the engine control unit are then set to the corresponding opening angle.
In the event of an incorrect self-diagnosis, the PWM line is grounded. (Possibly also a certain voltage level) This is then evaluated by the ECU as an error.
The control unit supposedly recognizes a 2KOhm resistor in the PWM line (to ground) as an existing (and error-free) actuator.
I own a Cete module. This apparently waits (time-controlled?) for the diagnosis mode. Then it takes over the actuator. I get it because, despite the flap button being closed, it gets loud for a moment and only then does the exhaust flap close completely.
Maybe I'll manage to deal with it properly in winter.
I was considering buying the Renntech more out of interest in seeing how they intervene in the controller area network, not to try to reverse engineer it, just curiosity. I was looking for a used one because I am not all that interested or needing fully opened exhausts all the time at the cost of the Renntech.
On the PWM, since these devices go 100% open they only need to complete the ground and no need to pulse like the ECU does.
I was considering buying the Renntech more out of interest in seeing how they intervene in the controller area network, not to try to reverse engineer it, just curiosity. I was looking for a used one because I am not all that interested or needing fully opened exhausts all the time at the cost of the Renntech.
On the PWM, since these devices go 100% open they only need to complete the ground and no need to pulse like the ECU does.
All the Best,
Acta
Be interesting to see how the Cete integrates so much better and learn why it needs to eliminate the cold start function. Given both have to go through the test sequence and both need to end with the flaps given back to control of the ECU to avoid a fault. It feels like he perfect world would be the Cete, with cold start.
Thought I would jump back in here. Some of the ideas how these flaps work and how the interventions of the Cete/Renntech devices function are getting a little wayward.
Starting from the end, the exhaust flaps return to a "home" position at the end of every ignition cycle. This is a must even with the intervention devices because at startup, the flaps MUST go through a diagnostics startup test otherwise DTCs will be set. There are a series of P-xxxxxx (powertrain faults) assigned to both startup diagnostics and simple operating functions and controlled through the ECU (N3/10). I'll list the codes at the end.
Tuners can go through a data table with hack software and manually "uncheck" operating DTCs so the ECU simply quits reporting them. I've done this numerous times in tunes. However, the diagnostics software is hard code that is inaccessible. Tuners are always doing workarounds to this and the workarounds are always clugey. Long story short, the diagnostics have to run and these devices bypass the operating functions (open/close/partially open) by sending full voltage to the flap motors, but not before the diagnostics run on every startup cycle. If there is doubt this happens, look at the harnesses supplied with the devices. If it were a simple matter of supplying full voltage to the flaps there would only need to be two wires - a ground and an ignition switchable voltage feed.
The other important part of the level of sophistication - both the Cete and the Renntech devices are bypassing the diagnostics (and allowing them to happen) via a splice into the controller area network (CANBUS). If this didn't happen, the flaps would fail at diagnostics. Once diagnostics pass then full voltage is sent to the flap motors keeping them 100% open. Even though the ECU will send varying voltages to the flap motors during various operating cycles (different RPMs, different selectable performance modes, etc.) there are no more functional tests other than opens, shorts, sticking flaps (via turbo pressure sensor inputs that are out of expected values at performance RPMs).
So, a couple of ideas that are not true:
The flaps are not kept open after ignition shutdown. The voltage needed to do that alone would kill a battery before morning.
The intervention is not simply a +v and ground bypass.
The flaps open 100%, at times, with no intervention, but those moments are in certain selectable settings, RPMs ECTs and ETC positions. They are not limited to only 75%, but when they are 100% open, so many other sounds are happening the driver isn't noticing more exhaust sound.
Here are the codes I am aware that are assigned to the exhaust flaps. Some are operating and others are startup diagnostics (exhaust flap 2 is the right side flap):
So the cold start sensation even after the car warms up with these devices is only a placebo effect?
Be interesting to see how the Cete integrates so much better and learn why it needs to eliminate the cold start function. Given both have to go through the test sequence and both need to end with the flaps given back to control of the ECU to avoid a fault. It feels like he perfect world would be the Cete, with cold start.
For what it's worth, the ASR/RT mod bypasses the stock system. So moving through the drive modes wouldn't have an effect. It would be working per the design.
That said, your remote switching on/off should have a very audible difference. If it doesn't, something is wrong with your module, the installation, or the valves.
Sorry Skilly I just want to be clear;
18 GTR, warmed in S+ or R remote switching from Stock Open to *ASR/RT Open* back and forth will yield no audible difference at idle or +RPM. The only ammunition I have to refute your claim that MY module/install/valves are faulty is that i've watched the official CETE video of an 18' GTR with them showcasing no difference per my scenarios. Also Whalekiller with an 18' GTR field tested after I made scandalous claims about our beloved Valve Modules in this thread.
18 GTR, warmed in S+ or R remote switching from Stock Open to *ASR/RT Open* back and forth will yield no audible difference at idle or +RPM. The only ammunition I have to refute your claim that MY module/install/valves are faulty is that i've watched the official CETE video of an 18' GTR with them showcasing no difference per my scenarios. Also Whalekiller with an 18' GTR field tested after I made scandalous claims about our beloved Valve Modules in this thread.
No worries but I still I don't know what you are trying to say. The Cete and ASR/RT operate in a completely different way.
Refuting my claim about the RT unit by showing me a Cete video operation is like showing me how to eat an apple and then saying Im eating a banana wrong because I peel it before eating. If the system is bypassing the factory button and opening/closing the values with a remote, it would make sense if it doesn't make a difference of you are in S+ or Race.
we keep using ASR/RT and the Cete Module in the same sentence. They both get to the same place (manipulation of the valve positioning) but operate and get there in a very different way. Watching a Cete video to better understand an ASR module's function won't get you there. Here is a copy of the cheat sheet I shared about a year ago on this subject in another thread (it was just as confusing and I think it had 45+ pages of input from the forum members):
STOCK:
cold start valve position default: 100% open but closes to default close after warm cycle - approximately 30 seconds exhaust valves open at start (post warm up): NO saves exhaust valve setting (open, close etc) from previous run cycle: NO exhaust open setting: manual or when drive settings set to S+ or RACE, I (if programmed) valve setting when selected: <100% (limited open to manage noise; even more so in Gen2 facelift) for complete details see @Acta_Non_Verba very detailed explanation above
CETE:
cold start valve position default: CLOSED exhaust valves open at start (post warm up): NO saves exhaust valve setting (open, close etc) from previous run cycle: NO exhaust open setting: manual operation or when drive settings set to S+ or RACE valve setting when selected: 100% remote switch operation to activate/deactivate the modification: NO (hardwired only) factory exhaust button work per factory function: YES
RENNtech/ASR: button 1 (on): overrides all factory functions and opens the valves to 100% open button 2 (off): reverts back to factory settings saves exhaust valve setting (open, close etc) from previous run cycle: YES remote switch operation to activate/deactivate the modification: YES factory exhaust button work per factory function: NO
we keep using ASR/RT and the Cete Module in the same sentence. They both get to the same place (manipulation of the valve positioning) but operate and get there in a very different way. Watching a Cete video to better understand an ASR module's function won't get you there. Here is a copy of the cheat sheet I shared about a year ago on this subject in another thread (it was just as confusing and I think it had 45+ pages of input from the forum members):
STOCK:
cold start valve position default: 100% open but closes to default close after warm cycle - approximately 30 seconds exhaust valves open at start (post warm up): NO saves exhaust valve setting (open, close etc) from previous run cycle: NO exhaust open setting: manual or when drive settings set to S+ or RACE, I (if programmed) valve setting when selected: <100% (limited open to manage noise; even more so in Gen2 facelift) for complete details see @Acta_Non_Verba very detailed explanation above
CETE:
cold start valve position default: CLOSED exhaust valves open at start (post warm up): NO saves exhaust valve setting (open, close etc) from previous run cycle: NO exhaust open setting: manual operation or when drive settings set to S+ or RACE valve setting when selected: 100% remote switch operation to activate/deactivate the modification: NO (hardwired only) factory exhaust button work per factory function: YES
RENNtech/ASR: button 1 (on): overrides all factory functions and opens the valves to 100% open button 2 (off): reverts back to factory settings saves exhaust valve setting (open, close etc) from previous run cycle: YES remote switch operation to activate/deactivate the modification: YES factory exhaust button work per factory function: NO
Skilly....you said up above that CETE basically takes away the valves automatically opening on cold start. Can't I just press the exhaust button right away after I start the car with CETE to get them to open right up and get the same effect that it takes away? Is there any downside to keeping the valves closed when cold? In other words....why does the stock setting without any valve module open the valves at cold start?
I feel I prefer I might prefer the CETE because the exhaust button will still work as intended and basically open the valves 100%........I get the others have remote controls but it seems a bigger PIA to keep a remote around versus just pressing the dash exhaust button.
09-14-2022, 10:59 AM
