Notice the engine RPMs dropping before it warms up

BMW135pls · 02-26-2015, 12:00 AM

6AT here. I've noticed lately when I start driving on a cold engine, when I take my foot off the throttle, the RPMs immediately take a nosedive, and head straight for 1k, where I guess some anti-stall software kicks in, and it'll bounce off of 1k until I downshift or hit the throttle again. Once the engine gets warmed up, it'll behave like normal and slowly drop from the RPM it was resting, at a rate relative to how fast the car is slowing down.

Now I'm not saying there's anything wrong with this, but it is pretty peculiar behavior, and this is the first vehicle I've driven that I've noticed this. I'm wondering if this is a software controlled phenomenon because the engine knows it's cold, or if this is just a behavioral property of how an engine runs when it's cold.

Yeineken · 02-26-2015, 06:23 AM

Best bet is that the software knows it's cold. My car does this when I pull out of the parking garage on a cold engine. But after 5 mins it goes away.

mtowle182 · 02-26-2015, 08:36 AM

same thing happens here. its annoying. i've just started warming the car up for 5-7 minutes in the morning because it was really grinding my gears.

sparky1_2007 · 02-26-2015, 08:37 AM

6AT as well here, mine does the same thing when the trans is cold. It goes away after driving for ~5-10 minutes. Usually by the time I make it to the freeway from my house the trans is acting normally.

135Pats · 02-27-2015, 11:34 PM

Same

Kosta135i · 02-27-2015, 11:41 PM

+1 same

MightyMouseTech · 02-28-2015, 08:28 AM

Your oil and trans fluid are cold and thick as hell. Cold going to cold.

twinboost_MD · 02-28-2015, 12:43 PM

Normal. My 135 starts at 1100 when I first start it then goes to 1000. Once it get to 900 I give it a little rev to 2 1/2 then another little one to 2k and let it settle to 600 rpm before I drive. Usually takes about 3 minutes max in sub 30 degree weather

BMW135pls · 02-28-2015, 12:53 PM

Quote:

Originally Posted by MightyMouseTech

Your oil and trans fluid are cold and thick as hell. Cold going to cold.

I know the BMW handbook says not to let the car idle, just get in and drive after the idle calms down, but if my car is behaving this way because its fluids haven't properly warmed up, does that mean I shouldn't be driving it yet?

MightyMouseTech · 03-01-2015, 03:02 PM

The fluids will never warm up just idling, you have to drive it.

Sitting idling is doing nothing but causing unnecessary wear.

02-26-2015, 12:00 AM	#1
BMW135pls First Lieutenant 90 Rep 341 Posts Drives: Bucket of screws and sadness Join Date: Jul 2014 Location: NJ, USA iTrader: (0)	Notice the engine RPMs dropping before it warms up 6AT here. I've noticed lately when I start driving on a cold engine, when I take my foot off the throttle, the RPMs immediately take a nosedive, and head straight for 1k, where I guess some anti-stall software kicks in, and it'll bounce off of 1k until I downshift or hit the throttle again. Once the engine gets warmed up, it'll behave like normal and slowly drop from the RPM it was resting, at a rate relative to how fast the car is slowing down. Now I'm not saying there's anything wrong with this, but it is pretty peculiar behavior, and this is the first vehicle I've driven that I've noticed this. I'm wondering if this is a software controlled phenomenon because the engine knows it's cold, or if this is just a behavioral property of how an engine runs when it's cold. __________________ Model: '08 135i N54 6AT Coupe ///M Sport - E85 + 93 = E30 Mods: AA DPs + Gen I - BMS JB4 (Race + Map 2) + DCI + OCC - Cobb CP - ///M RSFB + Front Control Arms - Koni Yellow - Swift Spec R - Vorshlag camber plates - MPSS 225/255 - x-ph Angel Eyes 160w
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02-26-2015, 06:23 AM	#2
Yeineken Colonel 1301 Rep 2,093 Posts Drives: '11 135i M Sport Join Date: Dec 2013 Location: Delmarva Peninsula iTrader: (3) Garage List '11 135i [8.20] '16 Ford Hatchback [0.00] '15 X5 [10.00]	Best bet is that the software knows it's cold. My car does this when I pull out of the parking garage on a cold engine. But after 5 mins it goes away. __________________ Pyrat Clone
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02-26-2015, 08:36 AM	#3
mtowle182 Private First Class 17 Rep 101 Posts Drives: 2009 135i Join Date: Aug 2014 Location: Maryland iTrader: (0)	same thing happens here. its annoying. i've just started warming the car up for 5-7 minutes in the morning because it was really grinding my gears. __________________
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02-26-2015, 08:37 AM	#4
sparky1_2007 Private 10 Rep 96 Posts Drives: 08' 135i Join Date: Jan 2014 Location: Michigan iTrader: (0)	6AT as well here, mine does the same thing when the trans is cold. It goes away after driving for ~5-10 minutes. Usually by the time I make it to the freeway from my house the trans is acting normally.
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02-27-2015, 11:34 PM	#5
135Pats Major General 456 Rep 6,478 Posts Drives: A few BMWs Join Date: May 2012 Location: Maryland iTrader: (3)	Same __________________ E88 N54 Alpinweiss/Coral Red/Motiv HTA 3586r Tial .82AR/Other stuff...652WHP F30 N55 XDrive EBII
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02-27-2015, 11:41 PM	#6
Kosta135i Second Lieutenant 16 Rep 202 Posts Drives: Black sapphire 135i 2008. Join Date: Aug 2013 Location: Connecticut iTrader: (1)	+1 same __________________ [B][COLOR="Red"]Vrsf 3'' Dps~Vrsf 7'' FMIC~AA Gen 2 Exhaust ~BMS DCI ~VRSF CP with Tial BOV~Cobb V3 With Custom PTF E40 stg2+ Tune
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02-28-2015, 08:28 AM	#7
MightyMouseTech Major General 4338 Rep 6,196 Posts Drives: 13 135i 6MT LeMans Blue MSport Join Date: Feb 2013 Location: Ottawa, Canada iTrader: (0)	Your oil and trans fluid are cold and thick as hell. Cold going to cold.
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02-28-2015, 12:43 PM	#8
twinboost_MD Private First Class 19 Rep 188 Posts Drives: AW 135i Join Date: Feb 2015 Location: Washington, DC iTrader: (0)	Normal. My 135 starts at 1100 when I first start it then goes to 1000. Once it get to 900 I give it a little rev to 2 1/2 then another little one to 2k and let it settle to 600 rpm before I drive. Usually takes about 3 minutes max in sub 30 degree weather __________________ E46 M3 ---> AW 135i on Coral Red - JB4 w/MHD Backend - Alpina B3 - Koni Yellows - H&R Super Sport Springs - Powerflex Rear Upper Shock Mounts - ///M Strut Tower Bar
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03-01-2015, 03:02 PM	#10
MightyMouseTech Major General 4338 Rep 6,196 Posts Drives: 13 135i 6MT LeMans Blue MSport Join Date: Feb 2013 Location: Ottawa, Canada iTrader: (0)	The fluids will never warm up just idling, you have to drive it. Sitting idling is doing nothing but causing unnecessary wear.
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