DTC Question...

yeefoo335 · 06-10-2010, 01:04 AM

For years now my friends and I, most of whom have BMW's as well have always assumed that leaving DTC inactive, in other words, when you start the car, not touching the DTC button on the dash as opposed to activating DTC, pressing the button once wastes more gas? May sound stupid but I am wondering if anyone else has ever though of that or if it is in fact true...seeing as how leaving DTC inactive makes the car slower, not only when you bog between shifts but just accelerating in general, leads me to believe that it might waste more gas. If i may have confused any of you DTC inactive=light off DTC active=light on. Is there any proof behind this?

AS335i · 06-10-2010, 01:43 AM

DTC does not make the car slower...DTC is the Dynamic Stability Control that works with DSC and all it does it help with traction and other issues. It does hinder wheel spin but does not effect power or anything, there is no reason why it would hurt gas mileage.... Only way that it could possibly hurt gas mileage would be if you turn off DTC and floor it around corners and get your revs up or do a burnout which would eat up gas. If you do that with DTC on it will cut power

mechanixhorseman · 06-10-2010, 06:50 AM

I think you're misunderstanding. DTC is on by default. Every time you start your car. It is OFF when you press the button and the light comes on. The only reason the light comes on at all is to remind you that its off.

Same thing goes for stability control.

2kaccordocoupe · 06-10-2010, 07:22 AM

Quote:

Originally Posted by mechanixhorseman

I think you're misunderstanding. DTC is on by default. Every time you start your car. It is OFF when you press the button and the light comes on. The only reason the light comes on at all is to remind you that its off.

Same thing goes for stability control.

+1
And in theory with it off you may burn more gas as you will probably be screwing around tossing the rear end out

fdsasdasdf · 06-10-2010, 09:14 AM

Quote:

Originally Posted by mechanixhorseman

I think you're misunderstanding. DTC is on by default. Every time you start your car. It is OFF when you press the button and the light comes on. The only reason the light comes on at all is to remind you that its off.

Same thing goes for stability control.

Actually, BMW is really weird and has it backwards.

DTC is on when you hit the button, but what it's really doing is turning off traction control/engine management while leaving DSC on. When the DTC light is on, DTC is turned on. When the DSC light is on, DSC is turned off.

http://www.bmw.com/com/en/insights/t...n_control.html

Ron1n · 06-10-2010, 09:44 AM

This debate drives me batty.

http://www.e90post.com/forums/showthread.php?t=319519

Read that thread.

Alexander · 06-10-2010, 10:31 AM

No when you press the DTC button once it limits the computer to 30% control (DTC DSC). If you hold it for 5 seconds or so it turns everything 100% off, meaning 0% computer interference.

mechanixhorseman · 06-10-2010, 10:38 AM

Quote:

Originally Posted by Zell

Actually, BMW is really weird and has it backwards.

DTC is on when you hit the button, but what it's really doing is turning off traction control/engine management while leaving DSC on. When the DTC light is on, DTC is turned on. When the DSC light is on, DSC is turned off.

http://www.bmw.com/com/en/insights/t...n_control.html

I don't want to come off as douchey or anything, but you just contradicted yourself in that statement and agreed with me at the same time. Maybe you meant DTC is on before you hit the button.

When you press the button (once, and for less than 4 seconds) traction control is off and stability control is still on. When you press and hold the button for 4 seconds or more, both DTC and DSC are off. Both DSC and DTC are always on by default, unless disabled.

The reason you can't use cruise control while the DTC light is on is because DTC is OFF.

granadablanca · 06-10-2010, 10:39 AM

Zell's post in that thread above couldn't be written better, thank you.

Quick question - if the car (DSC, w/ or w/o DTC) is modulating the throttle input, will it always show the warning icon on the dash as that happens?

Trying to diagnose a poor-acceleration/hesitation/low-power-from-a-stop issue, I was thinking maybe it was just the DSC restricting power, but then it occurred to me that maybe I should be seeing the icon flash on the dash in that case.

markinva · 06-10-2010, 10:41 AM

traction control != DTC

dynamic is a very important word here...

granadablanca · 06-10-2010, 10:42 AM

Quote:

Originally Posted by mechanixhorseman

I don't want to come off as douchey or anything, but you just contradicted yourself in that statement and agreed with me at the same time. Maybe you meant DTC is on before you hit the button.

When you press the button (once, and for less than 4 seconds) traction control is off and stability control is still on. When you press and hold the button for 4 seconds or more, both DTC and DSC are off. Both DSC and DTC are always on by default, unless disabled.

The reason you can't use cruise control while the DTC light is on is because DTC is OFF.

Argh! Could BMW have made this any more confusing? I think we're boiling down to the semantics now, with the "on" and "off" stuff.

PS - love your name. you must go WAY back in the day.

fdsasdasdf · 06-10-2010, 10:43 AM

Quote:

Originally Posted by mechanixhorseman

I don't want to come off as douchey or anything, but you just contradicted yourself in that statement and agreed with me at the same time. Maybe you meant DTC is on before you hit the button.

When you press the button (once, and for less than 4 seconds) traction control is off and stability control is still on. When you press and hold the button for 4 seconds or more, both DTC and DSC are off. Both DSC and DTC are always on by default, unless disabled.

The reason you can't use cruise control while the DTC light is on is because DTC is OFF.

It literally says on BMW's website that DTC is on when you hit the button. DSC is off when you hold it for 5 seconds.

Quote:

If the front wheels are stuck in snow and cannot spin properly, this leads to slip on the rear wheels (when they spin faster than the front wheels, generally a sign that performance has been exceeded) and DSC acts to change engine output: the power needed for forward movement is reduced. Switching to DTC has a positive effect on this situation, as traction is improved without a loss of power.

That's why it sounds backwards, since normally we attribute traction control lights with it being off. When DTC is on, traction control is off, but DSC is still on. It also says this in the manual. Attributing the name "Dynamic Traction Control" with no traction control as being "on" when the button is pushed sounds really weird, which is why I wish they would just say that DTC is off when you hit the button. Saves confusion.

Anyway, to the OP: I don't think it would really matter. I mean, technically yeah I guess if you turned on DTC you would waste more gas since engine output is no longer being limited when you start to slip the wheels and thus you're using more gas. But the amount of times that happens is not enough to make any real-world difference. I wouldn't worry about it. This reminds me of a physics question my teacher asked us on a test one time..."If you hit more bugs when driving, does it reduce gas mileage?" The answer was "Technically yes," but the real-life scenario answer was "No, it's completely negligible."

Alexander · 06-10-2010, 10:57 AM

DTC is on to 30%
Hold it all systems off.

mechanixhorseman · 06-10-2010, 11:03 AM

I wasn't aware that there were two modes of traction control on the vehicle, in addition to stability control. If that's the case, then I suppose I'm wrong. Either way its a horrible choice of names and words.

If you're turning one off, you probably are wanting to turn everything off. If I even touch that button its because I don't want the car to nanny me.

Quote:

Originally Posted by granadablanca

PS - love your name. you must go WAY back in the day.

Ya, not many people catch it.

Alexander · 06-10-2010, 11:06 AM

Quote:

Originally Posted by mechanixhorseman

I wasn't aware that there were two modes of traction control on the vehicle, in addition to stability control. If that's the case, then I suppose I'm wrong. Either way its a horrible choice of names and words.

If you're turning one off, you probably are wanting to turn everything off. If I even touch that button its because I don't want the car to nanny me.

Ya, not many people catch it.

I always have DTC limited to 30%. (AKA press the DTC button)
I rarely turn it off (hold the button) unless I'm doing autox.

fruition3000 · 06-10-2010, 01:10 PM

Here is an easy way to think of it
DTC off = Wheelspin
DSC off = Lateral Movement

I don't know which one cuts throttle.

mechanixhorseman · 06-10-2010, 01:30 PM

Quote:

Originally Posted by fruition3000

Here is an easy way to think of it
DTC off = Wheelspin
DSC off = Lateral Movement

Not sure if that's directed towards me, but I don't think anyone is debating the difference between traction and stability control, but rather the difference between the multiple levels of traction control available.

benny90 · 06-10-2010, 01:41 PM

Quote:

Originally Posted by AS335i

DTC does not make the car slower...DTC is the Dynamic Stability Control that works with DSC and all it does it help with traction and other issues. It does hinder wheel spin but does not effect power or anything, there is no reason why it would hurt gas mileage.... Only way that it could possibly hurt gas mileage would be if you turn off DTC and floor it around corners and get your revs up or do a burnout which would eat up gas. If you do that with DTC on it will cut power

Well put!

benny90 · 06-10-2010, 01:42 PM

Quote:

Originally Posted by Ron1n

This debate drives me batty.

http://www.e90post.com/forums/showthread.php?t=319519

Read that thread.

This is always a heated debate, everyone always thinks they're right...

granadablanca · 06-10-2010, 01:43 PM

Quote:

Originally Posted by granadablanca

Quick question - if the car (DSC, w/ or w/o DTC) is modulating the throttle input, will it always show the warning icon on the dash as that happens?

I'm bumping my own question before it gets overlooked, because I'm annoying like that.

Can anyone confirm that the dash icon will always flash when DTC is interfering with the throttle?

yeefoo335 · 06-10-2010, 03:38 PM

Well I am just going by what the idrive tells me, when I press the DTC button once, it says DTC active. So when the light is not on it is inactive. I forgot what it says for the DSC something like DSC limited and DTC active when I hold it for 3+ seconds. I read somewhere that the overall acceleration is slower with DTC inactive. Someone should test this with a Vbox and stock tune so you don't bog between shifts with any extra power. One run with DTC inactive and one run with DTC active then another run with DTC active and DSC limited. I am willing to bet you will get a slower time without any lights on the dash given that you dont break traction...

fruition3000 · 06-10-2010, 07:32 PM

Quote:

Originally Posted by yeefoo335

Well I am just going by what the idrive tells me, when I press the DTC button once, it says DTC active. So when the light is not on it is inactive. I forgot what it says for the DSC something like DSC limited and DTC active when I hold it for 3+ seconds. I read somewhere that the overall acceleration is slower with DTC inactive. Someone should test this with a Vbox and stock tune so you don't bog between shifts with any extra power. One run with DTC inactive and one run with DTC active then another run with DTC active and DSC limited. I am willing to bet you will get a slower time without any lights on the dash given that you dont break traction...

What?

These functions are traction and stability control mechanisms. DTC and DSC are on by default every time you get in the car. When you turn either one of them off the car will notify you. If the wheels start to spin Dynamic Traction Control will kick in and apply the brakes and cut throttle if needed. If you take a really hard turn and the back end of the car starts to slide out Dynamic Stability Control will kick in. When both of them are on they work together.

They do not make your car slower or affect performace unless you meet the conditions that requires these functions to activate.

06-10-2010, 01:04 AM	#1
yeefoo335 Private First Class 33 Rep 101 Posts Drives: 335i Join Date: Nov 2008 Location: Los Angeles iTrader: (1)	DTC Question... For years now my friends and I, most of whom have BMW's as well have always assumed that leaving DTC inactive, in other words, when you start the car, not touching the DTC button on the dash as opposed to activating DTC, pressing the button once wastes more gas? May sound stupid but I am wondering if anyone else has ever though of that or if it is in fact true...seeing as how leaving DTC inactive makes the car slower, not only when you bog between shifts but just accelerating in general, leads me to believe that it might waste more gas. If i may have confused any of you DTC inactive=light off DTC active=light on. Is there any proof behind this?
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06-10-2010, 01:43 AM	#2
AS335i Second Lieutenant 12 Rep 237 Posts Drives: e90 335i, f30 330i Join Date: May 2010 Location: Austin, Texas iTrader: (0) Garage List 2017 BMW 330i [0.00] 2009 BMW 335i [0.00]	DTC does not make the car slower...DTC is the Dynamic Stability Control that works with DSC and all it does it help with traction and other issues. It does hinder wheel spin but does not effect power or anything, there is no reason why it would hurt gas mileage.... Only way that it could possibly hurt gas mileage would be if you turn off DTC and floor it around corners and get your revs up or do a burnout which would eat up gas. If you do that with DTC on it will cut power
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06-10-2010, 06:50 AM	#3
mechanixhorseman Second Lieutenant 18 Rep 261 Posts Drives: 2007 335i Coupe Join Date: Jan 2010 Location: North County San Diego, CA iTrader: (0)	I think you're misunderstanding. DTC is on by default. Every time you start your car. It is OFF when you press the button and the light comes on. The only reason the light comes on at all is to remind you that its off. Same thing goes for stability control. __________________ ///2007 335i Coupe Space Metal Gray///Sports///Premium///6AT///Piano Black Forgestar 18" F14 8.5" front 10" rear///JB3///Cooling Mist CMGS Methanol Kit///aFe DCI///Stett Chargepipe///Tial BOV///BSH Oil Catch Can
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06-10-2010, 09:44 AM	#6
Ron1n Speed Demon 205 Rep 3,690 Posts Drives: 2021 M5C Join Date: Oct 2009 Location: Irvine iTrader: (6) Garage List 2021 M5 Competition [0.00] 2016 BMW 550i [0.00] 2011 335is [0.00] 2009 E93 M3 [10.00] 2010 335d [9.50]	This debate drives me batty. http://www.e90post.com/forums/showthread.php?t=319519 Read that thread. __________________ Current: '21 M5C, '15 X6 50i Previous: '18 M550i, '16 550i, '11 335is, '09 E93 M3 DCT, '10 E90 335d, '07 E90 328i
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06-10-2010, 10:31 AM	#7
Alexander Mad tyte EuR0 style boooi <--- Joke 212 Rep 2,472 Posts Drives: E30, E85, MKVI Join Date: Nov 2009 Location: Deal's Gap iTrader: (0)	No when you press the DTC button once it limits the computer to 30% control (DTC DSC). If you hold it for 5 seconds or so it turns everything 100% off, meaning 0% computer interference.
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06-10-2010, 10:39 AM	#9
granadablanca Private First Class 19 Rep 178 Posts Drives: E90 330i, AP1 Join Date: May 2010 Location: Los Angeles, CA iTrader: (0)	Zell's post in that thread above couldn't be written better, thank you. Quick question - if the car (DSC, w/ or w/o DTC) is modulating the throttle input, will it always show the warning icon on the dash as that happens? Trying to diagnose a poor-acceleration/hesitation/low-power-from-a-stop issue, I was thinking maybe it was just the DSC restricting power, but then it occurred to me that maybe I should be seeing the icon flash on the dash in that case.
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06-10-2010, 10:41 AM	#10
markinva Lieutenant 20 Rep 402 Posts Drives: 2021 M4 G82 Join Date: Nov 2008 Location: NOVA iTrader: (0)	traction control != DTC dynamic is a very important word here...
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06-10-2010, 10:57 AM	#13
Alexander Mad tyte EuR0 style boooi <--- Joke 212 Rep 2,472 Posts Drives: E30, E85, MKVI Join Date: Nov 2009 Location: Deal's Gap iTrader: (0)	DTC is on to 30% Hold it all systems off.
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06-10-2010, 01:10 PM	#16
fruition3000 Captain 29 Rep 769 Posts Drives: Down Ocean Drive Join Date: Apr 2010 Location: Le-Bron Town iTrader: (0)	Here is an easy way to think of it DTC off = Wheelspin DSC off = Lateral Movement I don't know which one cuts throttle. __________________ Last edited by fruition3000; 06-10-2010 at 01:39 PM..
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06-10-2010, 03:38 PM	#21
yeefoo335 Private First Class 33 Rep 101 Posts Drives: 335i Join Date: Nov 2008 Location: Los Angeles iTrader: (1)	Well I am just going by what the idrive tells me, when I press the DTC button once, it says DTC active. So when the light is not on it is inactive. I forgot what it says for the DSC something like DSC limited and DTC active when I hold it for 3+ seconds. I read somewhere that the overall acceleration is slower with DTC inactive. Someone should test this with a Vbox and stock tune so you don't bog between shifts with any extra power. One run with DTC inactive and one run with DTC active then another run with DTC active and DSC limited. I am willing to bet you will get a slower time without any lights on the dash given that you dont break traction...
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