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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 7 Series / 8 Series > 7 Series - E38 (1995 - 2001)

7 Series - E38 (1995 - 2001)

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  #1  
Old 04-24-2013, 09:33 PM
Danny Wolfe Danny Wolfe is offline
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Location: USA
 
Join Date: Feb 2011
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Mein Auto: 2001 740i
Exclamation Decarbonization????

I've had a rough idle for a long time now...i ran BG44k thru the injection system and also two cans thru the gas tank....car has new plugs, fuel filter, air cleaner, and sometimes runs smooth but at idle and at first take off the car shudders MILDLY...and intermittently....suggestions? I was wondering if i needed to go the de carbon using water mist thru the intake....anyone done this? IF SO PLEASE TELL ME HOW TO DO IT and what your results were.....THANKS!!!!
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  #2  
Old 04-25-2013, 04:45 PM
aom aom is offline
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Join Date: Jan 2002
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Mein Auto: 750i 740i 330ci
how are your throttle body gaskets, MAF, emissions hoses? Seems like it might not be carbon issue (kind of rare on these) and more like a vacuum issue? I'd guess.
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  #3  
Old 04-25-2013, 08:04 PM
Danny Wolfe Danny Wolfe is offline
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i sprayed cleaner CNC i think it is around the intake, and throttle body as well as the OSV and found nothing. I cannot find a vacum leak at all. I also sprayed the tube from MAF to the throttle body and the tube to the air cleaner, found no leaks or change in engine speed.
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  #4  
Old 04-25-2013, 08:08 PM
aom aom is offline
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Location: SoCal
 
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Mein Auto: 750i 740i 330ci
how's your MAF, when was it last replaced and how many miles to you have now?
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F01 750i Dark Graphite Metallic
M-Sport | Driver Assistance | Luxury Seating | Camera | Convenience | Premium Sound | 20" 303M Wheels | Ceramic Controls
MODS: BMS Stage 1 Tune | PedalBox | M-Sport Paddle Shift Steering Wheel | 5000k HID | Tint | Coded.
E38 740i Jet Black
Sport | PDC | Convenience | Sunshade | Navigation
MODS: Paddle Shift Retrofit | Brushed Aluminum Gauge Rings | Tint | MKIV NAV | 4500K HID | 3M DiNOC Carbon Fiber Trim | Heated Seats | Coded
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  #5  
Old 04-26-2013, 09:52 PM
Danny Wolfe Danny Wolfe is offline
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Location: USA
 
Join Date: Feb 2011
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Mein Auto: 2001 740i
my car has 189k miles. The maf was replaced at 138K. THANKS!
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  #6  
Old 04-27-2013, 12:49 AM
aom aom is offline
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Location: SoCal
 
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Mein Auto: 750i 740i 330ci
Hmm, interesting. Do you have access to a DIS or INPA? It might be interesting to see, when the car does do this, what the "Smooth Values" are for each cylinder. Kind of like... OK, this morning it's idling roughly and look, INPA says cylinder 5 is waaaay off, then after a few minutes, it's back to normal again and engine is smooth. Then you could start testing with that knowledge. But, let's say all values are just fine for all 8 cylinders, even w/ the rough idling, then we know it might be something post or pre cylinder... Like OSV or Cats. Just wild guess
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F01 750i Dark Graphite Metallic
M-Sport | Driver Assistance | Luxury Seating | Camera | Convenience | Premium Sound | 20" 303M Wheels | Ceramic Controls
MODS: BMS Stage 1 Tune | PedalBox | M-Sport Paddle Shift Steering Wheel | 5000k HID | Tint | Coded.
E38 740i Jet Black
Sport | PDC | Convenience | Sunshade | Navigation
MODS: Paddle Shift Retrofit | Brushed Aluminum Gauge Rings | Tint | MKIV NAV | 4500K HID | 3M DiNOC Carbon Fiber Trim | Heated Seats | Coded
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