DB11/DBSS exaust valves
Discussion
Just a word of caution. The exhaust valves on (I think all) VH cars are "dumb", in that the ECU gives instructions for the valves to operate but it has no idea where they are or if they responded - so you can add CCCharger controllers, or take out fuses and the car knows no different.
From what I've read the situation on the 2C cars is different, certainly for the MB V8 engines and, as they all use the MB electrical architecture, possibly for the V12 as well. On these cars the valve controllers are electrical, not vacuum, and they have a feedback circuit into the ECU that tells the car if the valves have obeyed instructions and are at the requested open/closed position, displaying an "engine fault" code if they aren't, possibly putting the car into "limp home" mode, and logging a DTC.
I'm not saying it's not possible as I've seen after-market exhaust systems with no valves for 2C cars, but they have to take the exhaust valve actuators into account.
From what I've read the situation on the 2C cars is different, certainly for the MB V8 engines and, as they all use the MB electrical architecture, possibly for the V12 as well. On these cars the valve controllers are electrical, not vacuum, and they have a feedback circuit into the ECU that tells the car if the valves have obeyed instructions and are at the requested open/closed position, displaying an "engine fault" code if they aren't, possibly putting the car into "limp home" mode, and logging a DTC.
I'm not saying it's not possible as I've seen after-market exhaust systems with no valves for 2C cars, but they have to take the exhaust valve actuators into account.
Fitted an ASR module (same as on my 720 & gtc) butmi wouldnt bother, the fully open valves that are only half open in sports + below 3k rpm, dont sound brilliant and i’m inclined to believe aston thought the same, it wasnt due to db levels but more to do with the note, it just sounds tractor like.
I did 2-300 miles at the weekend toggling between std mode and fully open and ended up level it in std. mode, not an expensive experiment but thought id post for others info.
No codes thrown up at all though, same valve module as all the ams2 astons looking at the spec sheet.
I did 2-300 miles at the weekend toggling between std mode and fully open and ended up level it in std. mode, not an expensive experiment but thought id post for others info.
No codes thrown up at all though, same valve module as all the ams2 astons looking at the spec sheet.
Valves on my 2016 DB11 V12 exhaust failed, likely was just sensor, but the engine went into limp mode as OP was describing. The AM engineer said that basically the system calibrates whether the valve is open or closed when the engine is turned on. If it cant check then it throws into limp mode and the gears kept changing at 3k even in manual mode. The strange thing was it didn't throw any warning lights.
The biggest challenge in fixing this was that AM wont just replace the valve or sensor, they replace the whole rear exhaust system!! Cost was £1,500. After some carful words with them we agreed I'd pay £500 and AM would pick up the rest. I wasn't happy but glad to get it done in the end.
The biggest challenge in fixing this was that AM wont just replace the valve or sensor, they replace the whole rear exhaust system!! Cost was £1,500. After some carful words with them we agreed I'd pay £500 and AM would pick up the rest. I wasn't happy but glad to get it done in the end.
GlassOfBollinger said:
Valves on my 2016 DB11 V12 exhaust failed, likely was just sensor, but the engine went into limp mode as OP was describing. The AM engineer said that basically the system calibrates whether the valve is open or closed when the engine is turned on. If it cant check then it throws into limp mode and the gears kept changing at 3k even in manual mode. The strange thing was it didn't throw any warning lights.
The biggest challenge in fixing this was that AM wont just replace the valve or sensor, they replace the whole rear exhaust system!! Cost was £1,500. After some carful words with them we agreed I'd pay £500 and AM would pick up the rest. I wasn't happy but glad to get it done in the end.
The biggest challenge in fixing this was that AM wont just replace the valve or sensor, they replace the whole rear exhaust system!! Cost was £1,500. After some carful words with them we agreed I'd pay £500 and AM would pick up the rest. I wasn't happy but glad to get it done in the end.
That is interesting. I didn't know that (with second century models), the exhaust valve positions are monitored at engine start.
With VH models it does not matter whether the valves are open, closed, or broken. The engine will start normally.
Those valves can be repaired too, if appropriate.
I wonder on the newer cars, why it matters what position the exhaust valves are in? Wouldn't have thought there would be much significant practical difference.
Some insight:
After around 2015ish exhaust flaps that bypass some or all of the muffler system to provide a more open exhaust, changed from a simple vacuum system to a much more sophisticated electronic one.
AM and every other late model performance car that I've come across now use a system like this. The flaps are now controlled by an electronic step motor at each side. The ECU (ECM) determines which position those step motors will be in upon startup and throughout the running RPM range. The signal voltage sent to these step motors come from the ECU and each reports back that they are, in fact, at the proper location as commanded. If not, the ECU reports a failure and sets a power train code as well as an orange check engine light.
As a performance tuner, I can see the exhaust data tables and manipulate them with other performance tune data changes.
I'll show some of the tables. These came from an AMG, essentially the same platform as used in AMs with the 4.0L V8s.
This is a blowout of the data tables used to set various running conditions - RPM, coolant temps, etc.
When things don't go well, maybe a failed step motor, or a stuck (often rusted) exhaust flap, some power train codes that can be produced:
After around 2015ish exhaust flaps that bypass some or all of the muffler system to provide a more open exhaust, changed from a simple vacuum system to a much more sophisticated electronic one.
AM and every other late model performance car that I've come across now use a system like this. The flaps are now controlled by an electronic step motor at each side. The ECU (ECM) determines which position those step motors will be in upon startup and throughout the running RPM range. The signal voltage sent to these step motors come from the ECU and each reports back that they are, in fact, at the proper location as commanded. If not, the ECU reports a failure and sets a power train code as well as an orange check engine light.
As a performance tuner, I can see the exhaust data tables and manipulate them with other performance tune data changes.
I'll show some of the tables. These came from an AMG, essentially the same platform as used in AMs with the 4.0L V8s.
This is a blowout of the data tables used to set various running conditions - RPM, coolant temps, etc.
When things don't go well, maybe a failed step motor, or a stuck (often rusted) exhaust flap, some power train codes that can be produced:
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