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Discussion Starter · #1 ·
Ok so this night be common knowledge but I'm asking because I can't find anything about it. I have a custom exhaust that g's a great rumble/growl at idle so it is very easy for me to pick up on exhaust note changes.

Has anyone noticed that when you change your settings from comfort or sport to advanced the exhaust note changes? The engine idles up very slightly, not enough for the rpm gauge to move, but enough to change the exhaust note dramatically. I know advanced is suppose to change suspension settings and throttle response, what else does it change?
 

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Anything that creates an electrical load will cause idle speed to increase momentarily as the alternator receives the draw and the ecu compensates with a subtle (or sometimes not so subtle) idle speed change.
 

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Discussion Starter · #3 ·
Anything that creates an electrical load will cause idle speed to increase momentarily as the alternator receives the draw and the ecu compensates with a subtle (or sometimes not so subtle) idle speed change.
It doesn't change momentarily, it stays like that. But what changes electrically from comfort/sport to advanced?
 

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Yes this happens on MT's iirc when you put it in advanced since the timing is slightly increased.
 

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This is common with my SR. The note actually gets deeper.
 

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Discussion Starter · #6 ·
Oh ok so it also changes timing. Anything else? Ignition?
And yes the note gets deeper. I found myself putting in advanced mode while I ran into the store just to come back out and here it. Such a gorgeous sound.
 

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It affects the variable valve timing points as well (or at least I am pretty sure it does), but I don't know why that would affect it at idle.
 

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Where did you get any of this info?
Somebody hook up the VIDA and look at parameters when the different SUM settings are selected.
It may be NOTHING more than the TCM ramps up line pressure and the load of pump is the sensation via higher engine load and the results of that (auto trans models only).
The Advanced setting does not get a get of jail free pass from the EPA so I doubt there is a cam timing change. There is a change of the mapping for APM and how the ECM responds with control of ETA.

The a/c compressor cycling makes your car, together with motor mounts not as well damped as when new, have a coarser feel.

I'd do some research but I'm out of town for two weeks and I have no R with me to investigate.
 

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I always just assumed that it had something to do with the struts receiving more current or something...in comfort/sport at idle my boost gauge reads at exactly 20in Hg, in advanced it reads at about 18 or 19in Hg. Of course when the AC compressor kicks in it jumps to about 15-16in Hg.
 

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I read somewhere that it changes the throttle mapping. I can't seem to find the thread now, but I definitely hear/notice the difference too.
 

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Discussion Starter · #11 ·
Where did you get any of this info?
Somebody hook up the VIDA and look at parameters when the different SUM settings are selected.
It may be NOTHING more than the TCM ramps up line pressure and the load of pump is the sensation via higher engine load and the results of that (auto trans models only).
The Advanced setting does not get a get of jail free pass from the EPA so I doubt there is a cam timing change. There is a change of the mapping for APM and how the ECM responds with control of ETA.

The a/c compressor cycling makes your car, together with motor mounts not as well damped as when new, have a coarser feel.

I'd do some research but I'm out of town for two weeks and I have no R with me to investigate.
It's not the engine or A/C. A/C is turned off and I know the difference between vibration and an exhaust note. I know the advanced setting affects throttle response, and of course the suspension, but I wouldn't be surprised if it did advance the timing just a tad. Kinda like dual loading an ECU with a flip switch for different tune maps. I had that on my civic but it was of course aftermarket, I don't know if volvo would put something that advanced on a car.
 

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Discussion Starter · #13 ·
Advanced changes the sound in my R....a lot more "gurggle" on idle/downshift especially. I always assumed it was the increased turbo response.
I will add that the turbo deff takes a little less time to spool whilst in advanced mode. Comfort and sport at idle there is not a discernible note of turbo spool. Advanced, you can hear it spooling.
 

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Oh ok so it also changes timing. Anything else? Ignition?
And yes the note gets deeper. I found myself putting in advanced mode while I ran into the store just to come back out and here it. Such a gorgeous sound.
Ignition IS timing
 
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