ZPOST
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   ZPOST > BMW Z4 Roadster and Coupe > General BMW Z4 Forum
  TireRack

SUPPORT ZPOST BY DOING YOUR TIRERACK SHOPPING FROM THIS BANNER, THANKS!
Post Reply
 
Thread Tools Search this Thread
      09-30-2010, 08:02 AM   #1
dekaliber
Major
74
Rep
1,143
Posts

Drives: '07 Z4MC, '11 JCW, '18 Z06
Join Date: Mar 2008
Location: Los Angeles

iTrader: (1)

RPM dip on startup?

I noticed this a few times in the past week or so and thought I'd post to see if anyone had any thoughts about it. On starting the car in the morning, the RPMs will typically hover at around 1100-1200 RPM for maybe 15-20 seconds, which is normal from my experience. However, in the last week I noticed that a few seconds after starting up the RPMs will suddenly dip below 1000 and then kick back up to 1200, for seemingly no reason. The car doesn't stall or anything but it's definitely a new behavior. Also I don't notice anything amiss during normal driving.

A few things that changed recently: I installed a fresh OEM air filter (Thursday), I used a bottle of Techron (Friday), and I had my first track weekend (Saturday-Sunday).

As for gas, I have always used Shell V-Power 93.

I didn't think it was a problem, but wanted to check to see if anyone had any ideas.
Appreciate 0
      09-30-2010, 08:07 AM   #2
Huz-Z
Brigadier General
Huz-Z's Avatar
Canada
843
Rep
4,051
Posts

Drives: Z4 3.0si, 328 XDrive, X5 35i
Join Date: Aug 2009
Location: Canada

iTrader: (0)

Is the weather starting to cool down a bit? It may have something to do with that, as the car adjusts its operation for different ambient temperatures.
__________________
Huz-Z


BMW Z4 3.0si Roadster. Montego Blue Metallic. Premium and Sport Package.
Appreciate 0
      09-30-2010, 08:07 AM   #3
esqu1re
Lieutenant Colonel
esqu1re's Avatar
41
Rep
1,855
Posts

Drives: M Coupe
Join Date: Jul 2010
Location: East Coast

iTrader: (0)

I don't know what's the problem, if there is one, but mine does the same thing once in a while. I use the same gasoline, old air filter, recently used techron in the last 1700 miles. I don't think those things would make it do that. It doesn't happen often. Perhaps it's something kicking on? Perhaps a bubble in the fuel line? i don't know.
__________________


///M Coupe: RPI Scoop, OE Strut, CDV, Volk RE30, SS Brake Lines, Stromung Exhaust
Appreciate 0
      09-30-2010, 12:40 PM   #4
BAK613
Enlisted Member
5
Rep
38
Posts

Drives: Z4 M Roadster (E85)
Join Date: Apr 2010
Location: Burke, VA

iTrader: (0)

Quote:
Originally Posted by dekaliber View Post
However, in the last week I noticed that a few seconds after starting up the RPMs will suddenly dip below 1000 and then kick back up to 1200, for seemingly no reason. The car doesn't stall or anything but it's definitely a new behavior. Also I don't notice anything amiss during normal driving.
I've had my 06 ZMR since February, it gets driven on weekends. The RPM dip (700-800 RPM) on startup always occurs after it has sat for a week.

I've thought about having the shop look at it, but of course they won't be able to replicate it, after I've driven it over there. <g>

Bruce
Appreciate 0
      09-30-2010, 12:51 PM   #5
rps
Captain
rps's Avatar
United_States
35
Rep
609
Posts

Drives: 2013 X1
Join Date: May 2009
Location: Pace, Fl

iTrader: (11)

My 06 will also do it once in a while. It usually lasts for no more than a few seconds and doesn't appear to be a problem. Mine started doing it after the lifters then head assembly was replaced. I am totally retentive about my car, but it doesn't seem to be a problem.
__________________
NB8S Past Garage: Z4, 135i. Present Garage: 2013 X Drive X1 2.8i.
Appreciate 0
      09-30-2010, 12:55 PM   #6
dekaliber
Major
74
Rep
1,143
Posts

Drives: '07 Z4MC, '11 JCW, '18 Z06
Join Date: Mar 2008
Location: Los Angeles

iTrader: (1)

Yes, the weather is cooling down a bit so in the morning it's in the high 50s/low 60s in my garage vs. 70+ as it has been.

I doubt it's the Techron since I put it in on Friday in the middle of a 3.5 hr drive and have since gone through 2 complete tanks of gas over the course of the weekend.

I'm not too worried about it. Mostly I just wanted to get a sense of whether this was pretty normal or if it's a sign of some larger issue.

Quote:
Originally Posted by BAK613 View Post
I've had my 06 ZMR since February, it gets driven on weekends. The RPM dip (700-800 RPM) on startup always occurs after it has sat for a week.
That was one of my thoughts as well. That was another thing that changed for me. Since I got the ZHP 2 months ago, I only drive the M coupe on weekends or at most once or twice during the week. Today was the first time I drove it since Sunday. Maybe stagnant fuel in the lines or something?
Appreciate 0
      09-30-2010, 01:04 PM   #7
007MCoupe
Lieutenant Colonel
007MCoupe's Avatar
United_States
91
Rep
1,546
Posts

Drives: '18 Sakhir M3 ZCP
Join Date: Jun 2010
Location: ( ///// )

iTrader: (5)

mine just started doing this too. I drive it daily. The temp has gotten a LOT cooler in the mornings. It's just a cold engine start. notice your tach has the rpm lit up al lthe way to like 5K then once it warms up it's settles down to 7500?
__________________
Appreciate 1
Ms. M0.00
      09-30-2010, 02:45 PM   #8
r4gs
Viper Driver
Singapore
36
Rep
1,311
Posts

Drives: F-16
Join Date: Aug 2010
Location: Singapore

iTrader: (2)

i've only just recently started experiencing these same symptoms, and it has indeed gotten a lot cooler in the mornings. i do notice that the dip in rpm occurs after a slightly longer than normal crank for engine start and after having sat overnight in approximately 60 degree temperatures.

btw, i've started leaving my air conditioning completely off when i start the car to help with getting it to start better. maybe i'm getting paranoid?
Appreciate 0
      09-30-2010, 03:54 PM   #9
GP20
Major
Canada
95
Rep
1,269
Posts

Drives: Z4M, F80 M3, 991.2 GTS
Join Date: Jan 2007
Location: Canada

iTrader: (5)

It's most likely the gas and ethanol in your area that are causing the cold start issue. It used to happen everyday to my '04 3.0i, even when I was filling up at Chevrons and Shells. Then I moved to a different area and started filling up at different gas stations and the problem went away instantly.

These days I fill up with Chevron 94 with 0.0% of ethanol and have never experienced the cold start issue again. The engine just fires up effortlessly with a really clean sound and stable idle.
__________________
2019 Porsche 911 4 GTS
2016 BMW M3
2008 BMW Z4M coupe
Appreciate 0
      09-30-2010, 04:36 PM   #10
dekaliber
Major
74
Rep
1,143
Posts

Drives: '07 Z4MC, '11 JCW, '18 Z06
Join Date: Mar 2008
Location: Los Angeles

iTrader: (1)

Incidentally, I was just reading about ethanol-free gas this morning because I had noticed the 10% max ethanol content stickers on the Shells around here for a little while. I wonder if the ethanol in the gas does something after sitting for more than a few days. Unfortunately, I don't think ethanol-free gas exists anymore in the Chicagoland area.

For me, the behavior always manifests as a sudden drop in RPMs within the first 10 seconds or so that goes back up right away. The dip never lasts longer than a half second or second.
Appreciate 0
      09-30-2010, 04:50 PM   #11
RBull
Captain
Canada
12
Rep
725
Posts

Drives: 2007 M Coupe
Join Date: Apr 2010
Location: Nova Scotia

iTrader: (0)

I have the same issue sporadically. It seems to be more common the longer the car sits.
Appreciate 0
      09-30-2010, 07:35 PM   #12
pokeybritches
Colonel
pokeybritches's Avatar
United_States
479
Rep
2,782
Posts

Drives: ESS/G-Power Z4M, VF Z4, 996tt
Join Date: Sep 2009
Location: Los Angeles

iTrader: (12)

Garage List
2006 BMW Z4M  [10.00]
2006 BMW Z4M  [8.50]
2003 BMW Z4 3.0i  [9.00]
You can add me to that list of people experiencing the same symptoms. My 2003 3.0i has even had the RPM dip so low that the engine died and I had to restart. I would have guessed it was an ECU issue, like it has a hard time adapting to cold starts with different gas. It's something I would think software could fix, rather than forcing the driver to change the variables (use different gas, etc).
Appreciate 0
      09-30-2010, 07:53 PM   #13
MZHammer
Lieutenant
MZHammer's Avatar
45
Rep
516
Posts

Drives: E85 Z4M, F82 M4
Join Date: Sep 2010
Location: Hamilton, ON

iTrader: (2)

Garage List
2016 M4  [0.00]
2006 BMW Z4M Roadster  [0.00]
My 06 Z4MR experiences the 'blip' on startup too, after it has sat for a while or when it gets cooler. First time it happened, my heart sank, but it seems to be a pretty normal thing, judging by responses here and in another thread on this site. A lot of guys seem to eliminate it with 0% ethanol gas.
Appreciate 0
      10-01-2010, 01:46 PM   #14
thenewkid
Private
0
Rep
54
Posts

Drives: 06' 3.0si
Join Date: Apr 2010
Location: fort worth, texas

iTrader: (1)

i had the same issue a while back, started in the spring to it in and they acutally found the same problem. they changed my idle rpm a little lower and solved the problem, before i was idling around 12 now it around 9 just my $.02
Appreciate 0
      10-01-2010, 02:04 PM   #15
RickC
Private
United_States
4
Rep
74
Posts

Drives: 335xi Coupe and Z4
Join Date: Apr 2010
Location: Upstate NY USA

iTrader: (0)

One thing worth a try (works for me) is to turn the key to the point just prior to the engine cranking but allowing the fuel pump to start and prime for about 5-10 seconds then turn to start. Having the fuel pump started and primed gets rid of most of the dip for me
Appreciate 0
      10-01-2010, 05:16 PM   #16
dekaliber
Major
74
Rep
1,143
Posts

Drives: '07 Z4MC, '11 JCW, '18 Z06
Join Date: Mar 2008
Location: Los Angeles

iTrader: (1)

Quote:
Originally Posted by RickC View Post
One thing worth a try (works for me) is to turn the key to the point just prior to the engine cranking but allowing the fuel pump to start and prime for about 5-10 seconds then turn to start. Having the fuel pump started and primed gets rid of most of the dip for me
Interesting. So what you're saying is turn it to position 2 for a few seconds and let everything turn on before starting the engine? I didn't realize the fuel pump came on in position 2, but it seems plausible that it would do the trick since the RPM drop seems fuel related.
Appreciate 0
      10-01-2010, 06:47 PM   #17
VinnieAces
Lieutenant Colonel
VinnieAces's Avatar
Canada
92
Rep
1,603
Posts

Drives: Imola Red Z4MC
Join Date: Apr 2010
Location: Ontario, Can

iTrader: (2)

Garage List
2006 Z4 M Coupe  [8.00]
my 06 MC does this too
__________________
///M - Some Mods 'N Stuff
Appreciate 0
      10-01-2010, 09:06 PM   #18
r4gs
Viper Driver
Singapore
36
Rep
1,311
Posts

Drives: F-16
Join Date: Aug 2010
Location: Singapore

iTrader: (2)

as per the few suggestions concerning ethanol as a constituent of gas, i have been regularly filling up with shell v-power, which contains 'up to 10% ethanol'. i only experience the rpm dip symptom sporadically and cannot recreate it on demand. it does seem to be related to fuel/fuel pump somehow.
Appreciate 0
      10-01-2010, 09:45 PM   #19
Caddyshk
M = Midlife Crisis
Caddyshk's Avatar
Canada
65
Rep
2,006
Posts

Drives: 2006 Z4MC Interlagos
Join Date: May 2007
Location: Fort Erie, Ontario, Canada

iTrader: (0)

Normal...
__________________
2006 Z4MC - #LL93158
SS Race Cans, RE X Pipe, DKF Sec 1, Fabspeed Headers, OE STB, AS Shifter, Dave Z CDV, GC Coil Overs, Stoptech lines, Hawk DTC Pads, RE Clutch Stop, RE Transmission Mounts, Vibra-Technics Engine Mounts, Poly FCAB & RTAB, LeatherZ M Shift Boot, Tekarbon Rear Spoiler, CF Grills, Advan RS DGM
Appreciate 0
      10-02-2010, 11:12 AM   #20
sirmalloc
code monkey
sirmalloc's Avatar
United_States
7
Rep
74
Posts

Drives: 2006 Z4M Roadster Imola/Imola
Join Date: Dec 2008
Location: Tampa, FL

iTrader: (0)

I had the same issue while my car was under warranty. Since I could never recreate it while at the dealer, I took a video of it doing the rev drop for a few days and showed it to my service advisor. They performed some kind of software update and it hasn't happened since. The receipt for the service just says "Fault stored. Need to program DME."
Appreciate 0
      10-02-2010, 04:55 PM   #21
PrinceMiro
Lieutenant
PrinceMiro's Avatar
United_States
39
Rep
407
Posts

Drives: z4 3.0i
Join Date: Apr 2008
Location: CNJ

iTrader: (3)

Is anyone else experiencing this problem at some other time besides starting the car? This happens to me sometimes after I've driven the car for a few minutes (not after I've driven it longer than 5 minutes though). I've experienced the dip on startup where the engine has shut off and I've had to turn the car back on, but the last time that happened was over a year ago. Just last week, however, maybe 5 minutes after starting the car and driving, I was at a red light and I got the dip along with vibrations (not violent). The vibrations I'm talking about are the ones that happen when your engine turns off. Any ideas?
Appreciate 0
      10-02-2010, 09:27 PM   #22
Z4Murder
Major
Z4Murder's Avatar
United_States
28
Rep
1,110
Posts

Drives: > speed limit
Join Date: Apr 2010
Location: Buffalo, NY

iTrader: (1)

i get an rpm dip on a cold start about a few seconds after it cranks
__________________
2007 TiAg ///MCoupe
* Dinan strut bars * ZHP knob * RPI scoop * Ultimate Pedals * RE Diablo * 3.91 TMS gears * Apex PS7 * Eventuri intake* Nitto NT05 * TMS pullies * Zeck CDV * RE tranny mounts * Tekarbon * Mstache 2 *
'14 Jeep Grand Cherokee Overland Hemi... No more snow for the M!
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 Off



All times are GMT -5. The time now is 12:35 PM.




zpost
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST