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11-25-2009 12:31 PM #1
Q: Engine management while cold vs. warm 2006, N
My 2006, E53, N62, 4.4, 13.000 km, stutters a bit (maybe misfiring) on rpms up to approx. 1.500 when cold during warm-up. A few minutes (ca. 5) after temp gauge reaches top, the stuttering stops abruptly and all is fine.
Anyone that can share some facts about what differentiates engine management during warm-up from engine management while warm?
11-27-2009 08:33 PM #2
- Tampa, FL, United StatesMember No: 6805
- Join Date
- Feb 2001
- Rep Power
The cold start system, as I recall, simply increases the rpm's and enrichens the fuel mixture, sort of like a choke would. If its sputtering it sounds more like too rich rather than too lean. Not much help, I know. Can you pull codes and have a meter to test? Mine simply quit working a few years ago and I pretty much knew what it was and took it to the dealer and they replaced a sensor. I don't have an extra Saturday to self diagnose and probably would have replaced the wrong gizmo anyway. Ask for a free loaner. Maybe someone else with more experience has a suggestion.
11-28-2009 10:28 PM #3
Maybe unrelated, but...
There was a TSB on my 1999 M Roadster to reprogram the engine management computer to smooth out the idle on warmup. I never had it done and the car stutters until it warms up.
It might be worth a call to the dealer service rep, or if you have the ETK/TIS discs, search for a TSB on the subject.
Also, I presume your secondary air pump, etc. is functioning properly, correct?
12-01-2009 05:08 PM #4
12-01-2009 10:48 PM #5
11-29-2009 05:14 AM #6
Re: Q: Engine management while cold vs. warm 2006, N
My previous X5 was an '04 N62 and it did the exact same thing you are describing, albeit only when the outside temperature was below appx. 40 F degrees. Any outside temperature warmer than that and my N62 engine never missed a beat when cold.
To minimize the nuisance of the slight hesitation when cold, I simply drove the vehicle in the SPORT transmission mode -- thereby running the engine above 1500 rpm as much as possible -- until the temperature gauge reached the normal range.
I had my local BMW dealer test drive my X5 to diagnose the cold weather hesitation, but the technician said he couldn't notice any abnormality. He claimed that the early valvetronic engines (2002 through 2006) are not unknown to develop rough idle symptoms when cold, and left it at that.
I later read somewhere that BMW's valvetronic engine design attempts to meet stringent SULEV emission regulations by severely retarding the timing when cold (when emissions are at their worst), which the valvetronic engine can handle because of its ability to adjust valve lift minutely. I then surmised that the engine management system might be using 40 F degrees as a marker for substantially retarding the timing, which is kind of what the hesitation felt like, i.e., a random misfire (but only a very slight misfire).
The following summer I took my X5 out of storage (I drive my E39 during the summer months) and had my local BMW dealer perform a fuel injection system cleanse for $150 (the technician injects fuel system cleaner directly into the fuel rails while running the engine), thinking that perhaps it might allow the valves/injectors to operate more efficiently when the engine was cold. However, I sold my X5 before winter set in and never did get a chance to test my theoretical remedy.
That being said, I now drive a 2006 E53 with the same N62 engine and I haven't really noticed the slight hesitation below 1500 rpm that my 2004 had, yet the temperatures are below 40 F degrees everyday . . . so I'm not sure what to say.
You might do a search on the E65 board, since those early models had the same N62 engine. My recollection when I looked over there, though, was that the E65s' hesitation problems were much more severe (i.e., rough idling when cold) and not really analogous to what I was experiencing with my 2004 N62.
12-01-2009 05:01 PM #7
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