335i seems to lose more power than before when AC is on

satz · 12-06-2016, 08:35 PM

Hi all

my unmodded 335i auto E90 seems to lose more power than I remember last summer when I switch on AC.

The car just loses its 'edge' as soon as I switch on AC. Doesn't spin the tyres, more laggy from standing start.

AC itself seems to run normally. No strange noises from engine bay. Wasn't using the AC all winter, so perhaps I've forgotten the power loss?

Same petrol. The only change was that recently had the plugs changed as part of service.

Any ideas?

cheers

MJ80. · 12-06-2016, 09:48 PM

Honestly i have days in mine where i think "fucking hell its slow today" and other times ill gass it and it will scare the shit out of me.

tawfeeqh · 12-06-2016, 09:50 PM

n54lyf lol

titium · 12-06-2016, 10:48 PM

Quote:

Originally Posted by MJ80.

Honestly i have days in mine where i think "fucking hell its slow today" and other times ill gass it and it will scare the shit out of me.

I've never had that mine feels the exact same every time i drive it.

i barely even notice the difference with the ac on.

DR-JEKL · 12-06-2016, 10:54 PM

Quote:

Originally Posted by satz

Hi all

my unmodded 335i auto E90 seems to lose more power than I remember last summer when I switch on AC.

The car just loses its 'edge' as soon as I switch on AC. Doesn't spin the tyres, more laggy from standing start.

AC itself seems to run normally. No strange noises from engine bay. Wasn't using the AC all winter, so perhaps I've forgotten the power loss?

Same petrol. The only change was that recently had the plugs changed as part of service.

Any ideas?

cheers

do some logs

Boganian Rubes · 12-06-2016, 10:54 PM

Get a shorter serpentine belt and do an AC delete

satz · 12-06-2016, 11:05 PM

MJ80- glad I'm not the only one that feels the car is different every drive.

I do the 'adaptive reset' pretty often. Not sure if it works, but makes me feel better

Could something have been done wrong in the recent service?

Socket · 12-07-2016, 02:14 AM

I run AC all the time... should I turn it off to get another 50kw??

Boganian Rubes · 12-07-2016, 02:17 AM

Quote:

Originally Posted by Socket

I run AC all the time... should I turn it off to get another 50kw??

Lol unrealistic numbers much

It's around 47

Socket · 12-07-2016, 02:22 AM

Quote:

Originally Posted by satz

Hi all

my unmodded 335i auto E90 seems to lose more power than I remember last summer when I switch on AC.

The car just loses its 'edge' as soon as I switch on AC. Doesn't spin the tyres, more laggy from standing start.

AC itself seems to run normally. No strange noises from engine bay. Wasn't using the AC all winter, so perhaps I've forgotten the power loss?

Same petrol. The only change was that recently had the plugs changed as part of service.

Any ideas?

cheers

it is impossible to accurately gauge output or performance by perception especially over a time period as long as a year

DrJ is right you need to do logs and get the data to see if your car is operating at peak condition or is losing pep over time

Doesn't really help you at the moment, but if you really feel the car is sluggish, do the usual maintenance like a walnut blast, coils and oil change (plugs are new so no need for those)

If it is really slug like then maybe there is a boost leak, check the rubber vac lines to see if any are split or have disconnected, check the diverter valves for leaks (or get the mechanic to check for leaks) the charge pipe hose might have come off the intercooler (passenger side front corner) etc etc

maybe what you need is a tune, JB4 and MDH flash is totally safe and will give you a good lift in performance... lots of peeps are concerned about putting on a flash tune (i was one of them once) The only danger is getting the mod bug and ending up like me

Testercles · 12-07-2016, 02:26 AM

Also a possibility for what you're noticing: Our cars are slower on hot days as the air isn't as dense so there may be a correlation between days you choose to crank the AC and external temperature.

Socket · 12-07-2016, 02:34 AM

Quote:

Originally Posted by Boganian Rubes

Lol unrealistic numbers much

It's around 47

hahaha is disagree Rubes 48

Avex · 12-07-2016, 02:51 AM

Quote:

Originally Posted by MJ80.

Honestly i have days in mine where i think "fucking hell its slow today" and other times ill gass it and it will scare the shit out of me.

This. Even on a n52, after a good warmup, boy does the car fly. I climb to 90kmh so quickly sometimes i tend to end up speeding on 70kmh streets without realising it until I see all the cars in my rearview mirror. That and the car generally feels smoother and the cabin feel from 60-110kmh feels no different.

This becomes especially so after a particularly long ride 100km+.

titium · 12-07-2016, 03:22 AM

Quote:

Originally Posted by Testercles

Also a possibility for what you're noticing: Our cars are slower on hot days as the air isn't as dense so there may be a correlation between days you choose to crank the AC and external temperature.

this difference is marginal. the ecu targets a set load to determine boost. (stock tune or mhd V7 and up)

hotter days the ecu will target more boost to make up for the lower density air. the only time you'd notice a performance difference is at high altitudes.

Testercles · 12-09-2016, 12:18 AM

Quote:

Originally Posted by titium

Quote:

Originally Posted by Testercles

Also a possibility for what you're noticing: Our cars are slower on hot days as the air isn't as dense so there may be a correlation between days you choose to crank the AC and external temperature.

this difference is marginal. the ecu targets a set load to determine boost. (stock tune or mhd V7 and up)

hotter days the ecu will target more boost to make up for the lower density air. the only time you'd notice a performance difference is at high altitudes.

Good info, I didn't know that. Makes sense that they'd allow for it.

Socket · 12-09-2016, 12:31 AM

Quote:

Originally Posted by titium

this difference is marginal. the ecu targets a set load to determine boost. (stock tune or mhd V7 and up)

hotter days the ecu will target more boost to make up for the lower density air. the only time you'd notice a performance difference is at high altitudes.

What? like in a hot air balloon ?

DOCTOR.Y · 12-11-2016, 08:05 AM

um...this is common in E90 320i as I have experienced, in 325 its not noticeable, in 335 AC can hardly affect the power.

CashedUpBogan · 12-12-2016, 11:10 AM

Quote:

Originally Posted by Avex

Quote:

Originally Posted by MJ80.

Honestly i have days in mine where i think "fucking hell its slow today" and other times ill gass it and it will scare the shit out of me.

This. Even on a n52, after a good warmup, boy does the car fly. I climb to 90kmh so quickly sometimes i tend to end up speeding on 70kmh streets without realising it until I see all the cars in my rearview mirror. That and the car generally feels smoother and the cabin feel from 60-110kmh feels no different.

This becomes especially so after a particularly long ride 100km+.

must be accelerating at a blistering rate to leave cars driving normally in your mirror

:

7smurfs · 12-12-2016, 08:35 PM

Don't know if it's in my head or not but my car feels faster after my car has been driven any distance and then shut off and turned back on.

Could be because on cold start I baby it aka <3k revs and then let it loose once at 90 degrees.

Also, getting a FMIC gave the car more consistent results.

12-06-2016, 08:35 PM	#1
satz Lieutenant Colonel 388 Rep 1,680 Posts Drives: 2019 BMW X3 M40i Join Date: Dec 2014 Location: A land down under iTrader: (0)	335i seems to lose more power than before when AC is on Hi all my unmodded 335i auto E90 seems to lose more power than I remember last summer when I switch on AC. The car just loses its 'edge' as soon as I switch on AC. Doesn't spin the tyres, more laggy from standing start. AC itself seems to run normally. No strange noises from engine bay. Wasn't using the AC all winter, so perhaps I've forgotten the power loss? Same petrol. The only change was that recently had the plugs changed as part of service. Any ideas? cheers
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12-06-2016, 09:48 PM	#2
MJ80. Major 204 Rep 1,103 Posts Drives: E92 335i DCT Individual Join Date: Oct 2013 Location: Gold Coast, Australia. iTrader: (0)	Honestly i have days in mine where i think "fucking hell its slow today" and other times ill gass it and it will scare the shit out of me.
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12-06-2016, 09:50 PM	#3
tawfeeqh Major 166 Rep 1,175 Posts Drives: 2007 BMW e90 335i Join Date: Jun 2015 Location: Melbourne, Australia iTrader: (0)	n54lyf lol
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12-06-2016, 10:54 PM	#6
Boganian Rubes Lieutenant Coal Burner 162 Rep 1,639 Posts Drives: 2008 BMW 320d e90 Join Date: Aug 2015 Location: Australia, Melbourne iTrader: (0)	Get a shorter serpentine belt and do an AC delete
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12-06-2016, 11:05 PM	#7
satz Lieutenant Colonel 388 Rep 1,680 Posts Drives: 2019 BMW X3 M40i Join Date: Dec 2014 Location: A land down under iTrader: (0)	MJ80- glad I'm not the only one that feels the car is different every drive. I do the 'adaptive reset' pretty often. Not sure if it works, but makes me feel better Could something have been done wrong in the recent service?
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12-07-2016, 02:14 AM	#8
Socket Lieutenant General 4782 Rep 11,975 Posts Drives: 335i Join Date: Nov 2014 Location: Australia iTrader: (4) Garage List 2008 BMW E92 [0.00]	I run AC all the time... should I turn it off to get another 50kw??
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12-07-2016, 02:26 AM	#11
Testercles First Lieutenant 11 Rep 347 Posts Drives: 2008 E90 335iA Join Date: Apr 2014 Location: Adelaide iTrader: (0)	Also a possibility for what you're noticing: Our cars are slower on hot days as the air isn't as dense so there may be a correlation between days you choose to crank the AC and external temperature. __________________ Current: 2008 E90 335iA Sparkling Graphite Metallic Past: 2009 E90 LCI 323iA Black Sapphire Metallic, 2005 E46 325iA Black Sapphire Metallic, 1992 E34 535iA Glacier Blue BMW Driver's Club of South Australia member
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12-11-2016, 08:05 AM	#17
DOCTOR.Y Eric_Y 107 Rep 458 Posts Drives: 2016 340i, 2010 E92 M3 Join Date: Sep 2015 Location: Sydney iTrader: (0) Garage List 2016 bmw m3 f80 [0.00] 2010 M3 E92 [0.00]	um...this is common in E90 320i as I have experienced, in 325 its not noticeable, in 335 AC can hardly affect the power.
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12-12-2016, 08:35 PM	#19
7smurfs Captain 141 Rep 902 Posts Drives: M3 CS Join Date: Apr 2014 Location: Melbourne iTrader: (0)	Don't know if it's in my head or not but my car feels faster after my car has been driven any distance and then shut off and turned back on. Could be because on cold start I baby it aka <3k revs and then let it loose once at 90 degrees. Also, getting a FMIC gave the car more consistent results.
	Appreciate 0 Quote