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  #1  
Old 02-24-2010, 06:35 PM
pbstrickland pbstrickland is offline
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Location: Franklin, TN
 
Join Date: Sep 2008
Posts: 38
Mein Auto: 2001 740iA Sport
Dead spot in acceleration

In the morning when it is cold I sometimes get a rough idle and when I start driving and get a hesitation in the speed around the 1500-2000 rpm. This does not happen all the time add gets better where warmed up, if I gun it ,it will happen all the time. I have replaced the following.

OSV
all the coils
spark plugs
valve cover gaskets
checked for vacum leaks
Ais Mass Sensor

I'm running out of ideas, is it shop time?
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  #2  
Old 02-24-2010, 07:26 PM
drivinfaster's Avatar
drivinfaster drivinfaster is offline
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Location: in the sticks you piney
 
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Mein Auto: rescued bmw's
how many miles?? have you have your icv, and throttle plate cleaned recently?? fuel injection service may help as well.

these are pretty simple, common services that will help improve overall performance and help reduce the erratic idle quality as well as tip in hesitations while driving.

it would be my first place to start checking with the info provided.



df
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  #3  
Old 02-25-2010, 08:00 AM
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rrtec rrtec is offline
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Location: TN 37174
 
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Mein Auto: 540i/6 4/99
I would check again for vacuum leaks... spray some carb cleaner around the engine bay while its running and listen for changes in the idle ect..

How many miles on the car? low compression?
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Last edited by rrtec; 02-25-2010 at 08:02 AM.
  #4  
Old 02-25-2010, 05:11 PM
pbstrickland pbstrickland is offline
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Location: Franklin, TN
 
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Mein Auto: 2001 740iA Sport
Car has 100K on it. what is the icv?
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  #5  
Old 02-26-2010, 06:32 PM
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drivinfaster drivinfaster is offline
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Mein Auto: rescued bmw's
icv = idle control valve.

df
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  #6  
Old 03-05-2010, 09:00 AM
stlbmw stlbmw is offline
stlbmw
Location: Missouri
 
Join Date: Dec 2008
Posts: 225
Mein Auto: 2002 745Li/1999 528i
Quote:
Originally Posted by drivinfaster View Post
icv = idle control valve.

df
Yea, the IAC or ICV what ever your prefer is a good place. Last time I replaced the IAC it was due to a no start condition. Crank and crank, and crank...but no start defines a bad IAC. Not always but usually the case.
My thoughts are to check the above, but check the voltage coming from the Throttle position sensor, or drive by sensor coupling on the throttle body itself. If it is out of range, the cold start idle quality could be affected and create a poor idle.

One thing that comes to mind is a product the one intergtates into the accelerator pedal
assembly. It eliminates the inherent delay in the foot to pedal action when revving up the motor. Kinda like the way our old school cars used to operate with a throttle cable.


http://www.bmw-mania.com/web/Item/SPR2095/InvDetail.cfm

sltbmw
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