ac and the power button

KiokenM3 · 07-21-2009, 08:51 AM

i was driving over the wkend. it was hot as hell so i had the ac on blast. so when driving with the ac on you have that lag in the lower gears and you feel that hp loss, i was at a stop sign, decided to hit the power button for fun and

, it was not like the ac was even on. no lagging, barely seemed like any power loss. if you havent tried this yet with your ac give it a try. just thought id share

SoreHead · 07-21-2009, 09:07 AM

Quote:

Originally Posted by KiokenM3

i was driving over the wkend. it was hot as hell so i had the ac on blast. so when driving with the ac on you have that lag in the lower gears and you feel that hp loss, i was at a stop sign, decided to hit the power button for fun and

, it was not like the ac was even on. no lagging, barely seemed like any power loss. if you havent tried this yet with your ac give it a try. just thought id share

I never noticed any lag with aircon?

fpblue · 07-21-2009, 09:54 AM

According to the instructors at the M-school, the AC compressor automatically shuts down under hard throttle. I believe they said 80% throttle. It was 97 degrees in South Carolina and a few of us had the AC off trying to get every bit of HP we could get. They told us not to be crazy and that BMW designed it that way.

!Xoible · 07-21-2009, 10:34 AM

i use my mexican AC. it's just awesome. no lag, no quicker RPM drops resulting in shittier shifts. the thing is awesome!

J08M3 · 07-21-2009, 10:36 AM

Yep AC cuts of under WOT, most cars are like this.

foosh · 07-21-2009, 11:50 AM

The only thing the power button does is remap the amount the pedal must travel before you get to WOT. You're not getting any more power, and with the button off, you can do the same thing with your foot by pushing further. It is nothing more than a change in accelerator pedal feel and travel.

Perhaps that's why you thought the button was affecting your a/c, when all that was happening is that you were pushing your foot less to get to a/c compressor cut-out.

rbk1115 · 07-21-2009, 12:07 PM

Quote:

Originally Posted by SoreHead

I never noticed any lag with aircon?

+1

JCtx · 07-21-2009, 12:52 PM

Quote:

Originally Posted by foosh

The only thing the power button does is remap the amount the pedal must travel before you get to WOT.

Yep. Turn it on with steady throttle and you'd feel the 'surge' of power, but it's nothing more than depressing the gas pedal further in regular mode.

Two more comments. I found the regular mode extremely lethargic; the 'power' mode is the way my other cars behave, so I turned it on permanently.
And the beauty of BMW's compressor is you don't feel/hear it kick on and off like on most other cars

. Good day folks.

KiokenM3 · 07-21-2009, 01:35 PM

i never said you gain hp from the power but i already know that. i did say that you cant tell the ac is on when the power button is on. nodody can tell that they lose power when the ac is on???

zenderm3 · 07-21-2009, 06:58 PM

I'm amazed that it could be that noticable!

SoreHead · 07-21-2009, 07:27 PM

Quote:

Originally Posted by KiokenM3

nodody can tell that they lose power when the ac is on???

Nope. I never noticed it at all. I'll really concentrate next time I'm out in it and see if I can feel anything.

Can't right now as I'm dying from Bronchitis and the antibiotics don't seem to be having a bit an effect. Is it normal to cough up blood? Stupid sickness.

Any of you doctors on here have any tips on how to speed up the process? I'm 3 days without driving now and not loving it.

swamp2 · 07-22-2009, 02:10 AM

Strange, it gets hot and new issues seem to arise. The connection in my car between the AC and lag is brand new and very odd. In the morning with a "cold" car and during the stop and go's before getting on a main road. Just at the points when the car would lag (before my DCT software update) the AC fan speed goes to nearly off then bumps right back to the high level I had it set on. I'm certain this is a new phenomena post my recent DCT software update. Ugh... seems like the law of unintended consequences. Will they ever get this bloody software right...

Also, I've never noticed my AC being cut off - lowered or totally of during WOT and the thing I describe above is at very low throttle.

stylinexpat · 07-22-2009, 03:19 AM

If you plan on getting on it then it is better to turn AC off first. During normal driving I leave my AC on but if I plan on anything over 5500 RPM's then I switch my AC off.

gr8000 · 07-22-2009, 09:15 AM

Quote:

Originally Posted by swamp2

Just at the points when the car would lag (before my DCT software update) the AC fan speed goes to nearly off then bumps right back to the high level I had it set on.

VERY weird... Haven't noticed such a thing in mine, not before not after the latest software update. By "AC fan" I assume you mean the cabin fan (not the fan of the AC cooler in the engine).

M3 Montreal · 07-22-2009, 10:23 AM

Quote:

Originally Posted by elp_jc

Two more comments. I found the regular mode extremely lethargic; the 'power' mode is the way my other cars behave, so I turned it on permanently.
And the beauty of BMW's compressor is you don't feel/hear it kick on and off like on most other cars

. Good day folks.

+1 ... I always have the power button on. I find it easier to Blip and revmatch on downshifting with teh power button on. Once you get used to it it's hard going back.

foosh · 07-22-2009, 10:44 AM

Quote:

Originally Posted by gr8000

VERY weird... Haven't noticed such a thing in mine, not before not after the latest software update. By "AC fan" I assume you mean the cabin fan (not the fan of the AC cooler in the engine).

No, I assume he meant a/c compressor, which is one of the accessories, along with the alternator which is driven via belt by the crank pulley. It has a "clutch," which takes the load off the engine when not running. It is reported that the S65 has a circuit which automatically switches it off when you reach 80% WOT.

The HVAC fans can't have any influence.

gr8000 · 07-22-2009, 12:37 PM

Quote:

Originally Posted by foosh

No, I assume he meant a/c compressor, which is one of the accessories, along with the alternator which is driven via belt by the crank pulley. It has a "clutch," which takes the load off the engine when not running. It is reported that the S65 has a circuit which automatically switches it off when you reach 80% WOT.

The HVAC fans can't have any influence.

But he (swamp) clearly said AC fan, he didn't mention anything about the AC compressor. That's why I say its weird.

drey · 07-22-2009, 02:16 PM

"+1 ... I always have the power button on. I find it easier to Blip and revmatch on downshifting with teh power button on. Once you get used to it it's hard going back."

How does always having the power button on affect gas mileage? Any other possible disadvantage to leaving it on? Any mechanics out there?

JCtx · 07-22-2009, 02:20 PM

Quote:

Originally Posted by drey

How does always having the power button on affect gas mileage? Any other possible disadvantage to leaving it on?

Doesn't affect anything if you can control its 'sensitivity'. As I said, all my other cars feel exactly the same way than my M3 with 'power on', so I'm used to that 'sensitivity'. Try it and decide for yourself.

swamp2 · 07-22-2009, 02:46 PM

The cabin AC fan is what greatly diminishes in srength/output for me.

07-21-2009, 08:51 AM	#1
KiokenM3 Lieutenant Colonel 84 Rep 1,504 Posts Drives: LIFTED JEEP JK! Join Date: Dec 2008 Location: LA iTrader: (4)	ac and the power button i was driving over the wkend. it was hot as hell so i had the ac on blast. so when driving with the ac on you have that lag in the lower gears and you feel that hp loss, i was at a stop sign, decided to hit the power button for fun and , it was not like the ac was even on. no lagging, barely seemed like any power loss. if you havent tried this yet with your ac give it a try. just thought id share
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07-21-2009, 09:54 AM	#3
fpblue Second Lieutenant 17 Rep 281 Posts Drives: 2008 Jerez Black E90 Join Date: Jul 2009 Location: My Couch iTrader: (0)	According to the instructors at the M-school, the AC compressor automatically shuts down under hard throttle. I believe they said 80% throttle. It was 97 degrees in South Carolina and a few of us had the AC off trying to get every bit of HP we could get. They told us not to be crazy and that BMW designed it that way. __________________
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07-21-2009, 10:34 AM	#4
!Xoible Banned 837 Rep 46,029 Posts Drives: .... Join Date: Nov 2006 Location: . iTrader: (4) Garage List 2008 M3 [4.00] 2007 335i [9.00] 2008 528i [8.00] 2006 Infiniti - G35 ... [8.00]	i use my mexican AC. it's just awesome. no lag, no quicker RPM drops resulting in shittier shifts. the thing is awesome!
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07-21-2009, 10:36 AM	#5
J08M3 Major General 286 Rep 6,007 Posts Drives: 2011 M3 COUPE Join Date: May 2008 Location: NEW YORK iTrader: (8)	Yep AC cuts of under WOT, most cars are like this. __________________
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07-21-2009, 11:50 AM	#6
foosh Major 27 Rep 1,314 Posts Drives: 2008 M3 E93 Join Date: Mar 2009 Location: Annapolis, MD iTrader: (0)	The only thing the power button does is remap the amount the pedal must travel before you get to WOT. You're not getting any more power, and with the button off, you can do the same thing with your foot by pushing further. It is nothing more than a change in accelerator pedal feel and travel. Perhaps that's why you thought the button was affecting your a/c, when all that was happening is that you were pushing your foot less to get to a/c compressor cut-out. __________________
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07-21-2009, 01:35 PM	#9
KiokenM3 Lieutenant Colonel 84 Rep 1,504 Posts Drives: LIFTED JEEP JK! Join Date: Dec 2008 Location: LA iTrader: (4)	i never said you gain hp from the power but i already know that. i did say that you cant tell the ac is on when the power button is on. nodody can tell that they lose power when the ac is on???
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07-21-2009, 06:58 PM	#10
zenderm3 Lieutenant Colonel 95 Rep 1,996 Posts Drives: E36 M3 DY/2010 E92 M3 Join Date: Jun 2009 Location: Brisbane iTrader: (0)	I'm amazed that it could be that noticable! __________________ ________________ My ///M is in my garage .... and it is a beast! 2010 E92 M3 Space Grey \| Fully Loaded 1996 E36 M3 Dakar Yellow - SOLD 2004 Honda Accord Euro - SOLD
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07-22-2009, 02:10 AM	#12
swamp2 Lieutenant General 611 Rep 10,407 Posts Drives: E92 M3 Join Date: Sep 2006 Location: San Diego, CA USA iTrader: (3)	Strange, it gets hot and new issues seem to arise. The connection in my car between the AC and lag is brand new and very odd. In the morning with a "cold" car and during the stop and go's before getting on a main road. Just at the points when the car would lag (before my DCT software update) the AC fan speed goes to nearly off then bumps right back to the high level I had it set on. I'm certain this is a new phenomena post my recent DCT software update. Ugh... seems like the law of unintended consequences. Will they ever get this bloody software right... Also, I've never noticed my AC being cut off - lowered or totally of during WOT and the thing I describe above is at very low throttle. __________________ E92 M3 \| Space Gray on Fox Red \| M-DCT \| CF Roof \| RAC RG63 Wheels \| Brembo 380mm BBK \| \| Vorsteiner Ti Exhaust \| Matte Black Grilles/Side Gills/Rear Emblem/Mirrors \| \| Alekshop Back up Camera \| GP Thunders \| BMW Aluminum Pedals \| Elite Angels \| \| XPEL Full Front Wrap \| Hardwired V1 \| Interior Xenon Light Kit \|
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07-22-2009, 03:19 AM	#13
stylinexpat Major 415 Rep 1,427 Posts Drives: Join Date: Aug 2008 iTrader: (0)	If you plan on getting on it then it is better to turn AC off first. During normal driving I leave my AC on but if I plan on anything over 5500 RPM's then I switch my AC off.
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07-22-2009, 02:16 PM	#18
drey Second Lieutenant 21 Rep 222 Posts Drives: 2009 M3 Sedan, JZB/BB Join Date: Mar 2009 Location: Norcal iTrader: (0)	"+1 ... I always have the power button on. I find it easier to Blip and revmatch on downshifting with teh power button on. Once you get used to it it's hard going back." How does always having the power button on affect gas mileage? Any other possible disadvantage to leaving it on? Any mechanics out there?
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07-22-2009, 02:46 PM	#20
swamp2 Lieutenant General 611 Rep 10,407 Posts Drives: E92 M3 Join Date: Sep 2006 Location: San Diego, CA USA iTrader: (3)	The cabin AC fan is what greatly diminishes in srength/output for me. __________________ E92 M3 \| Space Gray on Fox Red \| M-DCT \| CF Roof \| RAC RG63 Wheels \| Brembo 380mm BBK \| \| Vorsteiner Ti Exhaust \| Matte Black Grilles/Side Gills/Rear Emblem/Mirrors \| \| Alekshop Back up Camera \| GP Thunders \| BMW Aluminum Pedals \| Elite Angels \| \| XPEL Full Front Wrap \| Hardwired V1 \| Interior Xenon Light Kit \|
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