E46 BMW Social Directory E46 FAQ 3-Series Discussion Forums BMW Photo Gallery BMW 3-Series Technical Information E46 Fanatics - The Ultimate BMW Resource BMW Vendors General E46 Forum The Tire Rack's Tire Wheel Forum Forced Induction Forum The Off-Topic The E46 BMW Showroom For Sale, For Trade or Wanting to Buy

Welcome to the E46Fanatics forums. E46Fanatics is the premiere website for BMW 3 series owners around the world with interactive forums, a geographical enthusiast directory, photo galleries, and technical information for BMW enthusiasts.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

Go Back   E46Fanatics > E46 BMW > ///M3 Forum

///M3 Forum
The BMW E46 ///M3 is the M version E46 and puts out an amazing 333 HP and 262 lb-ft of torque at stock specs! There are an amazing amount of modifications for both the coupe and convertible models so read up and get started modifying your cars today!

Reply
 
Thread Tools Search this Thread Rating: Thread Rating: 1 votes, 5.00 average. Display Modes
Old 01-04-2010, 02:26 PM   #1
infantrytroop22
Registered User
 
Join Date: Mar 2009
Location: SoCal
Posts: 114
My Ride: M3
Why do my RPMs drop when coming to a stop?

I have an '05 E46 M3 and the big issue I am having is the RPM's dropping when I come to a quick stop. They drop to between 600 and 800 before jumping right back up and holding steady at 900. It only happens when I come to a quick stop and it only seems to happen when the car is warm. The RPM's will also fluctuate up and down (about 50 to 100 variation) every once in a while at a stand still. My car has 27k miles, Delage intake, pulleys, supersprint section 2 pipe, and GruppeM muffler. Other than those few things, the engine is stock. I am taking my car in to my mechanic early next week, so I am hoping to get a good idea of what I may be looking at...Thanks.
infantrytroop22 is offline   Reply With Quote
Ads by Google

Guests, get your FREE E46Fanatics.com membership to remove this ad.
Old 01-04-2010, 03:16 PM   #2
KiNi///SoN
Registered User
 
Join Date: Dec 2009
Location: Miami
Posts: 30
My Ride: E46///M3
My car has done the same thing since the day i got it. Its not a big deal, and in some cases sounds kinda cool. I dont really think its a problem man. U can also prevent it by giving it a little gas in neutral while ur coming to that stop. Does it only happen when you got the clutch in? guessing ur not in an SMG.
__________________
KiNi///SoN is offline   Reply With Quote
Old 01-04-2010, 03:34 PM   #3
twboy1999
Registered User
 
Join Date: Mar 2003
Location: toronto
Posts: 148
My Ride: 03 CB/KIWI
same problem here (SMG)

only when the car is warm up, for me the problem got worse grdually, and it wont go away

i read somewhere ppl have the same problem and said it was the vanos solenoid, and my vanos did have problem, i clean up the vanos because it was very clug up, the car runs alot better now, but the RPM still drops

if u find out the peoblem, please let us know
twboy1999 is offline   Reply With Quote
Old 01-04-2010, 03:46 PM   #4
infantrytroop22
Registered User
 
Join Date: Mar 2009
Location: SoCal
Posts: 114
My Ride: M3
I should have specified. My car is an SMG.
infantrytroop22 is offline   Reply With Quote
Old 01-04-2010, 03:52 PM   #5
AtotheJ
Registered User
 
Join Date: Jun 2009
Location: San Diego
Posts: 163
My Ride: E46/E90/R53
http://forum.e46fanatics.com/showthr...ight=idle+drop
__________________
"Do or do not..there is no try.." Yoda
AtotheJ is offline   Reply With Quote
Old 01-04-2010, 03:59 PM   #6
dcf
Registered User
 
Join Date: Aug 2007
Location: Illinois
Posts: 763
My Ride: 02 e46 M3 SMG - LSB
That is the delay before the computer "pushes in the clutch pedal". Then, once the driveline is disengaged, the RPM's come back up to the normal operating idle. Nothing out of the ordinary in what you described.
dcf is offline   Reply With Quote
Old 01-04-2010, 08:28 PM   #7
toddkageals
Registered User
 
Join Date: May 2003
Location: Roanoke
Posts: 779
My Ride: 2008 335i sport/prem
Quote:
Originally Posted by dcf View Post
That is the delay before the computer "pushes in the clutch pedal". Then, once the driveline is disengaged, the RPM's come back up to the normal operating idle. Nothing out of the ordinary in what you described.
Hate to disagree with you and it's hard to tell just by a written description but what you wrote is NOT consistent with how my SMG transmission operates. When coming to stop, mine disengages smoothly right BEFORE 900 RPM. Now....I DO have an idle drop problem when the A/C is on but not when coming to a stop.
toddkageals is offline   Reply With Quote
Old 01-04-2010, 08:39 PM   #8
EndlessAP1
Registered User
 
Join Date: Jul 2004
Location: West Coast
Posts: 588
My Ride: e92 M3, e70 X5, TL
Quote:
Originally Posted by toddkageals View Post
Hate to disagree with you and it's hard to tell just by a written description but what you wrote is NOT consistent with how my SMG transmission operates. When coming to stop, mine disengages smoothly right BEFORE 900 RPM. Now....I DO have an idle drop problem when the A/C is on but not when coming to a stop.
That sounds normal to me. My NSXs, 350z, S2000, M3, etc all did that when AC is turned on or off. That is normal. Sorry to say, but true.
__________________
Acura TL
E92 M3
E70 X5
EndlessAP1 is offline   Reply With Quote
Old 01-04-2010, 09:30 PM   #9
toddkageals
Registered User
 
Join Date: May 2003
Location: Roanoke
Posts: 779
My Ride: 2008 335i sport/prem
Uhh...no...not in this case. I'm not talking about 100RPMs or so. In my car, engaging the A/C (or the automatic cycling of the compressor) causes the RPMs to drop so low that the engine vibrates the inside of the car. I have had this problem in all 3 of the BMWs that I have owned. I corrected the issue on my 328i by having the VANOS replaced (under warranty thank God). On my 330i I found a vac. leak that was causing the problem. Both cars had a rock steady idle (A/C on or not) once the repairs were completed. I will find the cause on the M3, I just have not had time to work on it yet. Again...I'm sure some RPM drop is normal but not to the extent that I have it!
toddkageals is offline   Reply With Quote
Old 01-04-2010, 09:35 PM   #10
toddkageals
Registered User
 
Join Date: May 2003
Location: Roanoke
Posts: 779
My Ride: 2008 335i sport/prem
Oh...I should mention that I temporarily fixed this "problem" by resetting the DME adaptation values using carsoft 6.5. Worked for about a day and then went back to dropping revs. once it started adapting again.
toddkageals is offline   Reply With Quote
Old 01-05-2010, 11:46 AM   #11
mirob
Registered User
 
Join Date: Mar 2009
Location: Texas
Posts: 273
My Ride: E46 M3
usually its a early symptom of VANOS Solenoid failure, happened to me...
mirob is offline   Reply With Quote
Old 01-05-2010, 02:28 PM   #12
infantrytroop22
Registered User
 
Join Date: Mar 2009
Location: SoCal
Posts: 114
My Ride: M3
The VANOS solenoid is not that expensive to fix, right?
infantrytroop22 is offline   Reply With Quote
Old 01-05-2010, 03:46 PM   #13
mirob
Registered User
 
Join Date: Mar 2009
Location: Texas
Posts: 273
My Ride: E46 M3
Quote:
Originally Posted by infantrytroop22 View Post
The VANOS solenoid is not that expensive to fix, right?
its easy, but not exactly cheap, you are looking at approximatelly $650 includeing the seal plate ($20), and I do recommend changing that as well...
mirob is offline   Reply With Quote
Old 01-05-2010, 04:52 PM   #14
twboy1999
Registered User
 
Join Date: Mar 2003
Location: toronto
Posts: 148
My Ride: 03 CB/KIWI
infantrytroop22

if u get it done, let us know how it goes
twboy1999 is offline   Reply With Quote
Old 01-05-2010, 04:52 PM   #15
infantrytroop22
Registered User
 
Join Date: Mar 2009
Location: SoCal
Posts: 114
My Ride: M3
How many hours of labor is it?
infantrytroop22 is offline   Reply With Quote
Old 01-05-2010, 08:31 PM   #16
twboy1999
Registered User
 
Join Date: Mar 2003
Location: toronto
Posts: 148
My Ride: 03 CB/KIWI
changing solenoid, should be under 1hr

read somehwere, only take like 30-40 mins to change
twboy1999 is offline   Reply With Quote
Old 01-05-2010, 10:10 PM   #17
m3e46freak
Registered User
 
Join Date: Feb 2009
Location: 'MERICA
Posts: 1,493
My Ride: e46/bike/Airplane?
Quote:
Originally Posted by twboy1999 View Post
same problem here (SMG)

only when the car is warm up, for me the problem got worse grdually, and it wont go away

i read somewhere ppl have the same problem and said it was the vanos solenoid, and my vanos did have problem, i clean up the vanos because it was very clug up, the car runs alot better now, but the RPM still drops

if u find out the peoblem, please let us know

Well since you spoke about it.. how did you clean up the vanos.. perhaps it will help my problem.
__________________
Rock Hard Abs Racing


2004 JB / Cinnamon SMG - NAV - Heated Seats
Sonic Tuning Spacers 15mm
Alcantara Wheel/Boot/Pillars
BMC filter
Carbon Fiber: Doors/Seat Back/Trim/Paddles
Scorza muffler
CSL Bumper/Trunk
ST Coilovers

m3e46freak@yahoo.com for outside contacting
m3e46freak is offline   Reply With Quote
Old 01-05-2010, 11:35 PM   #18
twboy1999
Registered User
 
Join Date: Mar 2003
Location: toronto
Posts: 148
My Ride: 03 CB/KIWI
Quote:
Originally Posted by DonovanM3 View Post
Well since you spoke about it.. how did you clean up the vanos.. perhaps it will help my problem.
no idea
my shop did it for me
twboy1999 is offline   Reply With Quote
Old 01-06-2010, 02:10 AM   #19
m3e46freak
Registered User
 
Join Date: Feb 2009
Location: 'MERICA
Posts: 1,493
My Ride: e46/bike/Airplane?
Cant be that hard.. hrm...
*search*
__________________
Rock Hard Abs Racing


2004 JB / Cinnamon SMG - NAV - Heated Seats
Sonic Tuning Spacers 15mm
Alcantara Wheel/Boot/Pillars
BMC filter
Carbon Fiber: Doors/Seat Back/Trim/Paddles
Scorza muffler
CSL Bumper/Trunk
ST Coilovers

m3e46freak@yahoo.com for outside contacting
m3e46freak is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Censor is ON





All times are GMT -5. The time now is 03:56 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
(c) 1999 - 2011 performanceIX Inc - privacy policy - terms of use