[daveymcmillan]

I'd recommend changing the spark plugs before changing the coil first... that fixed my issue altogether.

[GoRomeo]

Originally Posted by new0rder

this just to follow up my last post, my rough idling issue. so I did replace my ignition coil, just 1, everything works fine... until now I got another misfire, now its cylinder 6, I guess its on going, I am ordering another one.

Thanks for sharing and follow up. Great info. Keep us posted.

[bimmbo]

Been searching the forums for months on this issue and was never able to find anything solid . To be more exact, I had rough idle and bad hesitation on the highway accelerating from low RPM. Issue was worse when the AC was pumping hard to the point where if I pumped the throttle or tried to accelerate from low RPM (about 2500) for any extended period of time there would be hard engine stuttering. At some points I would get the SES light on and once that happened the car was barely driveable; basically couldn't accelerate. Restarting the car would clear the SES light and no codes could be found, but when the SES light was on I was able to pull a pending code: P0303 Cylinder 3 misfire. Great so now I had a place to start. Swapped the ignition coil with Cyl 2 and spark plug with Cyl 1 to see if I could get the SES fault to migrate to one of the other cylinders. While I had the engine cover off I decided to look at the eccentric shaft sensor connector as I had read about he seal leaking oil into it. Sure enough it had a bunch of oil in it, so I cleaned the connector and harness plug out with isopropyl and cotton swabs, then blew it dry with compressed air. Smeared dielectric grease on the harness plug and reconnected it. Took the car out for a spin and no rough idle and no hesitation while accelerating from low RPMS. Even pumped the throttle repeatedly with the AC cranking for the whole 15 minute drive and no hesitation! Took it for a second 15 minute drive an hour later and then a 30 minute the next day and issue still has not repeated. I'm sure the issue will resurface once the oil has had time to leak into the connector again, but at least I know what needs to be replaced: a $7 eccentric shaft sensor seal.

[kkasson]

Originally Posted by bimmbo

I'm sure the issue will resurface once the oil has had time to leak into the connector again, but at least I know what needs to be replaced: a $7 eccentric shaft sensor seal.

Typically the sensor fails internally which allows oil to leak into the pins. The seal keeps oil from leaking outside of the valve cover, but the oil will still leak into the connector.

I see that you're in CA, though. Does your 328i have an N51? If so the eccentric shaft sensor is covered by the SULEV warranty for 15 years/150k miles. I had mine (and the valve cover gasket) replaced for no charge at the dealership.

[DRAY8110]

Found in another thread, delete

[bimmbo]

kkasson, I understand what you mean about the shaft sensor seal, but I'm not sure I support based on my recent findings. Unfortunately my car is not a N51, it's an N52 from 9/2006; in any case I'm at 158k miles now.

Earlier this year the engine stutter, rough idle and on one occasion SES light returned so I decided to replace the eccentric shaft sensor seal. I did the valve cover gasket at the same time. But after doing this, I noticed that there was not much improvement on the idle and engine hesitation. (FML, that took me probably 8 hours.) I did not replace the eccentric shaft sensor though because the part was ~$200 and I'm a cheap ass.

At that point, I was pretty fed up because I thought I was going to have to replace the sensor and did not feel like spending the time, especially because the car was still driveable.

The next time I got the SES light I ran the code, and found Cylinder 3 and Cylinder 6 misfire codes. At this point my car had about 150k miles on it and I figured the ignition coils and spark plugs could probably use a replacement. So I bought an ignition coil and spark plug set for ~$160. Before I had a chance to install them, my starter went out...nothing like some motivation.

So I installed the new ignition coil set, while replacing the starter. And I also cleaned the MAF sensor which I had not done before. During the install, I took a look in the eccentric shaft sensor and did not find much of any liquid in there. Just some dielectric grease residue from the last work when I replaced the sensor seal. Cleaned the residue with alcohol for good measure. So kkasson, I don't think your statement is true that the eccentric shaft sensor seal cannot allow oil out of the valve cover and into the sensor connector, and that the sensor fails internally and oil comes through the pins (I guess the latter could happen just hasn't to mine).

Fired the car up and the engine idle is smooth, and there are no noticeable hesitations during acceleration. In fact, the car feels a bit peppier than before, likely from the new coils and plugs. I've put about 200 miles on the car so far and everything seems stable. It's even been pretty hot the last week (~90°F) so I've been blasting the AC and there's no sign of the rough idle.

Hopefully the issue's been fixed. If not, I'll update this thread again.