RPM dip on startup?

Hoa · 10-03-2010, 09:17 AM

mine did this as well. i drive mines daily. its not caused by the weather. it can be in the middle of the day during a hot summer and the engine is already warmed up, it would do it. i notice it would happen more if i drive and then stop for a few mins with the engine on. one time it shuts off on me on a cold start. the engine started and struggled for a few seconds and then shuts off. after that, it starts just fine again.

i took it to bmw and they claimed the car is normal since they cant pull any code and cant reproduce the problem. i just think that they dont want to do warranty work. if its out of warranty and i have to for out money, im sure they would do what it takes to find out the problem and charge me

PrinceMiro · 10-03-2010, 08:09 PM

Quote:

Originally Posted by Hoa

mine did this as well. i drive mines daily. its not caused by the weather. it can be in the middle of the day during a hot summer and the engine is already warmed up, it would do it. i notice it would happen more if i drive and then stop for a few mins with the engine on. one time it shuts off on me on a cold start. the engine started and struggled for a few seconds and then shuts off. after that, it starts just fine again.

i took it to bmw and they claimed the car is normal since they cant pull any code and cant reproduce the problem. i just think that they dont want to do warranty work. if its out of warranty and i have to for out money, im sure they would do what it takes to find out the problem and charge me

But you still don't know what's wrong?

thekurgan · 10-04-2010, 09:53 AM

Quote:

Originally Posted by PrinceMiro

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?

How many miles on your plugs and coil packs? I'm thinking fuel (filter/pump) or ignition and not always, will either cause a code.

007MCoupe · 10-04-2010, 10:10 AM

ok, i've got a quick question...

where do these codes show up and how would I check if i get one?

thekurgan · 10-04-2010, 10:16 AM

Quote:

Originally Posted by 007MCoupe

ok, i've got a quick question...

where do these codes show up and how would I check if i get one?

These:

http://www.peakeresearch.com/fcx3.htm

Work quite well, not expensive.

007MCoupe · 10-04-2010, 02:41 PM

a ha...thanks.

and back to your regularly scheduled thread...

thekurgan · 10-04-2010, 02:51 PM

Quote:

Originally Posted by 007MCoupe

a ha...thanks.

and back to your regularly scheduled thread...

That link didn't work, some kind of redirect, here's the model for our cars:

http://www.peakeresearch.com/fcx3.htm

Pheonix · 10-04-2010, 03:10 PM

How about the car was driven for about 2 hours (over 160 miles) then all sudden it shut down while you were doing about 50 MPH (at around 3000 RPM, 4th Gear)?

Hoa · 10-05-2010, 03:09 PM

Quote:

Originally Posted by PrinceMiro

But you still don't know what's wrong?

still dont know

r4gs · 10-05-2010, 05:17 PM

alright, just had a pretty clear cut rpm dip on startup again. have not topped up fuel in over a week so it's still on shell v-power from two weekends ago. car was sitting for two days and started up early in the morning with temperatures in the 60s, and a pretty severe rpm dip to almost 300 or so. no abnormal vibrations and dip lasted about half a second. engine ran completely normal thereafter. need to get a video of this.

PrinceMiro · 10-05-2010, 05:49 PM

Quote:

Originally Posted by thekurgan

How many miles on your plugs and coil packs? I'm thinking fuel (filter/pump) or ignition and not always, will either cause a code.

Just replaced plugs and coil packs a few months ago.

BAK613 · 10-05-2010, 09:36 PM

Quote:

Originally Posted by Hoa

>>it can be in the middle of the day during a hot summer and the engine is already warmed up, it would do it. i notice it would happen more if i drive and then stop for a few mins with the engine on.<<.

That sounds a lot like the conditions that produce vapor-lock. Something I've seen on fuel-injected piston aircraft engines, you can't get them re-started, but rarely on car engines.

Bruce

r4gs · 10-07-2010, 06:03 PM

i took a video on my phone this morning of this rpm dip phenomenon. simple straightforward crank-start with no prior fuel pump priming by leaving the key in position two. temperature was in the low 60s if that is at all a factor.

how can i post up the video without having to register on youtube et al?

em2b96p · 10-07-2010, 06:49 PM

my 04 3.0i does this if i havent driven it for a day or two. Ive learned to live with it, so i hope its not a problem since others are experiencing it as well

P-Man · 10-10-2010, 12:17 PM

Mine does it with every statup......briefly but still does it. No problem with running cold after the dip tho....

usurp · 10-18-2010, 02:39 AM

I had a similar issue but with mine it sometimes dipped so low it shut off the car and i had to restart it. Again it only happened on startup in the mornings.

Problem turned out to be my exhaust. Seems I hit a speed bump too hard and it loosened some welding between my rear exhaust and exhaust pipe which created a hole that was sucking air in or something. I got it welded and problem got fixed.

PrinceMiro · 10-18-2010, 02:54 PM

I can't remember where I heard this, but someone told me that it might be a leak somewhere in the vacuum system (hoses or whatever).

007MCoupe · 10-19-2010, 07:10 AM

so I've got a question. I noticed this morning that i've picked up this habit and want to know if it's bad.

To combat the dip, I rev the gas just a tad and it's ok. Start it up, quick blip, then off we go. There's no more dip! lol

pokeybritches · 10-19-2010, 08:09 AM

Quote:

Originally Posted by 007MCoupe

so I've got a question. I noticed this morning that i've picked up this habit and want to know if it's bad.

To combat the dip, I rev the gas just a tad and it's ok. Start it up, quick blip, then off we go. There's no more dip! lol

I wouldn't be revving your engine until oil pressure is built up. The only thing I'd do is give it just enough gas to keep from stalling (keeping rpm < 1000). If it's not in danger of stalling - don't do it.

007MCoupe · 10-19-2010, 03:19 PM

Quote:

Originally Posted by pokeybritches

I wouldn't be revving your engine until oil pressure is built up. The only thing I'd do is give it just enough gas to keep from stalling (keeping rpm < 1000). If it's not in danger of stalling - don't do it.

that's what i mean by blip. it really feels like it's going to die when the revs drop at startup, so i've been counteracting that with rev, no higher than 1K, 1200 at the MOST.

Z4Murder · 10-22-2010, 02:47 PM

Quote:

Originally Posted by 007MCoupe

that's what i mean by blip. it really feels like it's going to die when the revs drop at startup, so i've been counteracting that with rev, no higher than 1K, 1200 at the MOST.

i do the same thing, and have on other cars in the past. i dont believe its harmful at such a low rpm. as long as we're not liek the ricers who rev high on startup to make sure their fart cans are heard

dekaliber · 10-22-2010, 06:58 PM

Oddly enough, I haven't experienced this problem since I posted about it. Not sure I understand why, but I'm not complaining. I haven't been doing anything to "prime" it or anything, but maybe I am subconsciously making an effort to take it out more often.

10-03-2010, 09:17 AM	#23
Hoa Major 513 Rep 1,356 Posts Drives: BMW Join Date: May 2010 Location: GA iTrader: (9)	mine did this as well. i drive mines daily. its not caused by the weather. it can be in the middle of the day during a hot summer and the engine is already warmed up, it would do it. i notice it would happen more if i drive and then stop for a few mins with the engine on. one time it shuts off on me on a cold start. the engine started and struggled for a few seconds and then shuts off. after that, it starts just fine again. i took it to bmw and they claimed the car is normal since they cant pull any code and cant reproduce the problem. i just think that they dont want to do warranty work. if its out of warranty and i have to for out money, im sure they would do what it takes to find out the problem and charge me
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10-04-2010, 10:10 AM	#26
007MCoupe Lieutenant Colonel 92 Rep 1,546 Posts Drives: '18 Sakhir M3 ZCP Join Date: Jun 2010 Location: ( ///// ) iTrader: (5)	ok, i've got a quick question... where do these codes show up and how would I check if i get one? __________________ Become a ///Member!
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10-04-2010, 02:41 PM	#28
007MCoupe Lieutenant Colonel 92 Rep 1,546 Posts Drives: '18 Sakhir M3 ZCP Join Date: Jun 2010 Location: ( ///// ) iTrader: (5)	a ha...thanks. and back to your regularly scheduled thread... __________________ Become a ///Member!
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10-04-2010, 03:10 PM	#30
Pheonix Captain 371 Rep 999 Posts Drives: 2007 Z4 M Coupe 2012 e93 M3 Join Date: Sep 2008 Location: Bay Area, CA iTrader: (8) Garage List 2007 BMW/Z4MC [0.00]	How about the car was driven for about 2 hours (over 160 miles) then all sudden it shut down while you were doing about 50 MPH (at around 3000 RPM, 4th Gear)?
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10-05-2010, 05:17 PM	#32
r4gs Viper Driver 36 Rep 1,311 Posts Drives: F-16 Join Date: Aug 2010 Location: Singapore iTrader: (2)	alright, just had a pretty clear cut rpm dip on startup again. have not topped up fuel in over a week so it's still on shell v-power from two weekends ago. car was sitting for two days and started up early in the morning with temperatures in the 60s, and a pretty severe rpm dip to almost 300 or so. no abnormal vibrations and dip lasted about half a second. engine ran completely normal thereafter. need to get a video of this.
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10-07-2010, 06:03 PM	#35
r4gs Viper Driver 36 Rep 1,311 Posts Drives: F-16 Join Date: Aug 2010 Location: Singapore iTrader: (2)	i took a video on my phone this morning of this rpm dip phenomenon. simple straightforward crank-start with no prior fuel pump priming by leaving the key in position two. temperature was in the low 60s if that is at all a factor. how can i post up the video without having to register on youtube et al?
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10-07-2010, 06:49 PM	#36
em2b96p Private First Class 15 Rep 184 Posts Drives: cbr600rr Join Date: Feb 2006 Location: philadelphia iTrader: (0)	my 04 3.0i does this if i havent driven it for a day or two. Ive learned to live with it, so i hope its not a problem since others are experiencing it as well
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10-10-2010, 12:17 PM	#37
P-Man Enlisted Member 8 Rep 43 Posts Drives: 2006 Z4M Roadster Join Date: Oct 2010 Location: Seattle iTrader: (2)	Mine does it with every statup......briefly but still does it. No problem with running cold after the dip tho....
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10-18-2010, 02:39 AM	#38
usurp Private 7 Rep 52 Posts Drives: 2005 BMW Z4 Roadster - 3.0i Join Date: Apr 2008 Location: Kuwait iTrader: (0)	I had a similar issue but with mine it sometimes dipped so low it shut off the car and i had to restart it. Again it only happened on startup in the mornings. Problem turned out to be my exhaust. Seems I hit a speed bump too hard and it loosened some welding between my rear exhaust and exhaust pipe which created a hole that was sucking air in or something. I got it welded and problem got fixed. __________________ 2005 BMW Z4 Roadster - 3.0l, SMG, M Seats, Eisenmann exhaust and Hardtop.
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10-18-2010, 02:54 PM	#39
PrinceMiro Lieutenant 39 Rep 407 Posts Drives: z4 3.0i Join Date: Apr 2008 Location: CNJ iTrader: (3)	I can't remember where I heard this, but someone told me that it might be a leak somewhere in the vacuum system (hoses or whatever).
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10-19-2010, 07:10 AM	#40
007MCoupe Lieutenant Colonel 92 Rep 1,546 Posts Drives: '18 Sakhir M3 ZCP Join Date: Jun 2010 Location: ( ///// ) iTrader: (5)	so I've got a question. I noticed this morning that i've picked up this habit and want to know if it's bad. To combat the dip, I rev the gas just a tad and it's ok. Start it up, quick blip, then off we go. There's no more dip! lol __________________ Become a ///Member!
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10-22-2010, 06:58 PM	#44
dekaliber Major 74 Rep 1,143 Posts Drives: '07 Z4MC, '11 JCW, '18 Z06 Join Date: Mar 2008 Location: Los Angeles iTrader: (1)	Oddly enough, I haven't experienced this problem since I posted about it. Not sure I understand why, but I'm not complaining. I haven't been doing anything to "prime" it or anything, but maybe I am subconsciously making an effort to take it out more often.
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