[coriolis14]

Hey guys -

I have a N51, bone stock. I've noticed over the past week that my car began to develop a strong stutter/hiccup when I start it when warm (oil temp is between 180-220 - my car typically runs at 240 when fully warmed up). The best way I can describe the problem is that the engine feels like it's stuck in the crank phase for too long. On more than one occasion, the motor quit cranking mid-startup (I waited a couple minutes, and re-started without incident).

This does not happen when the engine is cold.

I checked for codes using BMWLogger and nothing has been thrown. I've run a lot of searches and couldn't find anything directly related to what I'm experiencing. The only service issues to note are that I replaced the coils/plugs at 53K (odo now at 72K) and I had the radiator replaced under warranty at 70K for a bad EAS sensor. Any advice/input would be appreciated!

[Agentphish]

Dude. Wtf.

You're like the 8th person to post about this, including myself, all of a sudden.

What is going on here!

http://www.e90post.com/forums/showthread.php?t=1088830
And
http://www.e90post.com/forums/showthread.php?t=1065542
And
http://www.e90post.com/forums/showthread.php?t=1088894

[Eddien123]

car used to do that quite often. Typically it was only when it was cold. However, after a starter replacement (due to failure) and a new set of spark plugs, it hasn't done it in about a year. And since we're in the middle of a cold winter it's safe to say the issue is solved. I'm not saying these two solve it but for me they did. I have to assume it was one of the two.


Also for the record OP, 240 is a very high temp to be running at. 195-212 is normal temps.

[coriolis14]

Originally Posted by Eddien123

car used to do that quite often. Typically it was only when it was cold. However, after a starter replacement (due to failure) and a new set of spark plugs, it hasn't done it in about a year. And since we're in the middle of a cold winter it's safe to say the issue is solved. I'm not saying these two solve it but for me they did. I have to assume it was one of the two.


Also for the record OP, 240 is a very high temp to be running at. 195-212 is normal temps.

I don't want to get too off-topic here, but I think my temps are high because I live in Los Angeles (usually pretty warm here; pretty much always 50ºF+) and I also have an N51 (higher heat = lower emissions, which is what this engine is supposedly all about). I haven't really had a problem with my engine temps before and my thread-searching has shown that my temps are within reasonable expectation.

Anyways, my stuttering always happens when warm (never when cold) so I'm not sure if we're comparing apples to apples here. In my particular case it looks like the VANOS solenoid might be dirty:

http://www.e90post.com/forums/showthread.php?t=1088830

I'll give that a try over the next week or so and report back with my findings!

[coriolis14]

So I cleaned my VANOS solenoids using this excellent DIY guide that can be found here:

http://www.e90post.com/forums/showthread.php?t=486201

I used carb cleaner to clean off both solenoids and then swapped the intake/exhaust solenoids. Not much buildup came out as it appears they were already fairly clean to begin with (the attached pic was taken before I cleaned them).

After I cleaned/replaced the solenoids, I tested the car with a brief run around the block (3 miles) and noticed a smoother engine ignition with no stuttering; this was with the engine cold, however. I'll have to try again when the engine is warm to see if the problem I originally posted about manifests itself again.

[Three_thirty_I]

Another reason why I insist on more frequent oil changes, and cleaning of these solenoids every now and again. Such an easy job actually, so really worth doing.

[coriolis14]

Attempted 2 warm starts after cleaning my solenoids yesterday and the problem has not shown itself...crossing my fingers and hoping the cleaning solved the problem!