550 cold start rough idle
10-12-2008, 02:02 PM
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My Ride: '06 550i
'84 Nissan S12 Turbo
I just recently bought a '06 550 with 36k miles. I've noticed that when I crank it after it's been sitting overnight, it will idle kinda rough for about 8-10....then smooths out and is fine.
Is this normal on these cars? I saw an old youtube vid of someone doing a cross country road test on a brand new '06 m5, and when he came out in the morning and cranked it up, he commented on the cold start rough idle, which sounded similar to what mine is doing.
Is this normal on these cars? I saw an old youtube vid of someone doing a cross country road test on a brand new '06 m5, and when he came out in the morning and cranked it up, he commented on the cold start rough idle, which sounded similar to what mine is doing.
10-12-2008, 07:41 PM
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My Ride: 07 550 i, mystic blue, black leather, cold weather package, nav, sport, shades, bags, rear heat, V1 hardwired.
05 F350 TD Crew Cab
04 Range Rover HSE
91 964 C4 Cabrio
07 997 Turbo Cabrio
The rough idle gets better with the latest program update, but never goes completly away. It gets worse the colder the car is, and the longer it sits without being driven. When the ambient temp climbs above 68, you should not notice any problems. If I were to guess, I would pin it to incomplete fuel atomization in the injectors.
10-12-2008, 08:13 PM
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10-13-2008, 03:04 AM
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My Ride: 2008 Space Gray 550i, Light Poplar Wood, Anthracite Head Liner, Sport Package, Sport Automatic Transmission, Cold Weather Package, Front Ventilated Comfort Seats in Black Nasca Leather, NAV, HUD, Active Steering, Comfort Access, Night Vision, Lane Deviation Warning, Active Cruise Control, Heated Rear Seats, Folding Rear Seats, Power Shade w/ Rear Side-Shades, Rear Air Bags, Logic 7, HD Radio, Sirius Satellite Radio, iPod/USB Adapter. Car in BMW Body Shop, estimated completion 01/24/07.
I have an '08 550i with 10K miles, and it exhibited this rough-idle behavior for the first time yesterday, while backing out of the garage. An engine alert symbol appeared. I shut the engine down for about 10 seconds, then restarted and all was fine. Pretty sure I have a ProgMan version well advanced beyond the v25.0 in the SIB. Weird.
Cal
Cal
10-13-2008, 07:02 AM
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My Ride: '06 550i
'84 Nissan S12 Turbo
I have to go to the dealer tomorrow....I'll see if they can check out what software version I have...or can I check? Just for kicks, how does a software update have anything to do with rough idling? Keep in mind I am a total noob to bmw......I've always owned Nissans.
I still need to find a service manual....is there one on here somewhere thats downloadable?
I still need to find a service manual....is there one on here somewhere thats downloadable?
10-14-2008, 12:02 AM
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My Ride: 07 550 i, mystic blue, black leather, cold weather package, nav, sport, shades, bags, rear heat, V1 hardwired.
05 F350 TD Crew Cab
04 Range Rover HSE
91 964 C4 Cabrio
07 997 Turbo Cabrio
My best guess...
When you turn the car on, a computer reads a series of information on the ambient temps, altitude, mass air density, and some other fine points, and then determines the correct fuel air mixture to use, and ignition sequence. The whole system is based upon an algorithmic program that always tries to adjust for maximum engine output, and cleanest emissions. But it is a continuing work of art, and some things need to be tweaked in the program. However, that being said, there are just some parameters that can't be readily solved. One, is the remaining fuel in the injectors after you shut down the car. The colder the car, the more dense the air molecules are, and the mixture gets changed for the fuel, which may or may not be the best set up for that particular combination of external environmental factors. After you start the car, this imbalance causes incomplete fuel atomization, hence the rough idle. This condition lasts until the fuel in the injector line has been blown through, and the correct mixture enters the car's cylinders. Other factors might also contribute as well, but the above statement represents my best guess as to why the idle is rough, and then goes away. It happens on my 210, but is easily solved with minute changes to the fuel mixture as the engine temps climb into the green.
When you turn the car on, a computer reads a series of information on the ambient temps, altitude, mass air density, and some other fine points, and then determines the correct fuel air mixture to use, and ignition sequence. The whole system is based upon an algorithmic program that always tries to adjust for maximum engine output, and cleanest emissions. But it is a continuing work of art, and some things need to be tweaked in the program. However, that being said, there are just some parameters that can't be readily solved. One, is the remaining fuel in the injectors after you shut down the car. The colder the car, the more dense the air molecules are, and the mixture gets changed for the fuel, which may or may not be the best set up for that particular combination of external environmental factors. After you start the car, this imbalance causes incomplete fuel atomization, hence the rough idle. This condition lasts until the fuel in the injector line has been blown through, and the correct mixture enters the car's cylinders. Other factors might also contribute as well, but the above statement represents my best guess as to why the idle is rough, and then goes away. It happens on my 210, but is easily solved with minute changes to the fuel mixture as the engine temps climb into the green.
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