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Discussion Starter · #1 ·
I have a 20 mo old '08 535i with 22k. For the first 15 or so months it was fine. In the past few months it has run rough for the first 30 seconds or so half the time I started it. I took it to the dealer and they found no error codes and, of course, it didn't do it for them.

Today it ran rough for a couple of minutes. This is much longer than I noted before, but I could still drive the car in my neighborhood w/o problem. For what it's worth, at the same time the iDrive computer crashed and re-booted (I presume since the screen went dark and then went thorough the usual startup stuff while I was driving down the street).

I get no warnings and the check engine light isn't set.

Another possible factor: the car sat for 2 weeks in an airport lot until our return yesterday. However, the car started up immediately w/o roughness and I drove it 100 miles at freeway speeds to return home.

These episodes don't effect drivability but they are certainly disconcerting.

Since I thought I might buy it off its 36 month lease, I got the oil changed at my expense at 7.5 k (and the covered service at 15k). Thus it's due for another oil change about now, so I could ask the dealer again to check it. However, should I be more forceful or just wait for a more serious failure? For that matter, should I forget the idea of buying the car and just turn it in at lease end (and save the cost of the 'extra' oil changes)? It does have the extended HPPF warranty, of course.

This certainly seems like a pretty slow-motion failure, if that's what's happening.

I love the car after the first 30 seconds! Your thoughts?
 

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Until your check engine light is illuminated, at which time a fault code will be stored in the DME, or you get an Engine Malfunction - Reduced Power warning on the iDrive, I doubt your dealer will be able to diagnose the issue and attempt to repair it. I experienced the same symptoms on my 535i earlier this year, although my CEL illuminated repeatedly. I still have my original HPFP. However, ultimately all six fuel injectors had to be replaced. No problems at all since.

IMO you may want to seriously consider returning the car at the end of the lease and moving on. I bought my car but plan to unload it just before 50K miles and maybe buy a CPO 550i. That is, as long as it has a naturally-aspirated engine.

Good luck and keep us posted.
 

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Discussion Starter · #3 ·
Today I noted the roughness off and on, but not for more than a minute. Of interest is the computer in the iDrive system is continuing to act up. No screens going blank, but much increased time is starting up... sometimes a minute or so before the audio system starts working. Any thoughts on whether the two problems are related? I don't see a connection.
 

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I doubt the two symptoms you described are connected in any way. My post relates only to the roughness you described. You may have to wait until your CEL appears, which it will sooner or later if the rough idling and ride continues, to get your dealer to diagnose and repair that issue.

My iDrive does strange things every now and then, but has never been a continuing problem. They are a little twitchy at times. Your dealer will tell you they cannot duplicate the problem unless it happens before their own eyes. I have read that the new iDrive in the 2010 model is supposed to be much improved.

Good luck.
 

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This is just a shot in the dark.... but the N54, due to its direct fuel injection design, is more prone to carbon deposit buildup on intake valves. I'm concerned about this as the miles start to add up, and that might be a cause for rough idle / rough running. I've heard some reports of people who have had to get their intake ports/valves cleaned at relative low mileage due to deposit buildup.
 
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