stewart@pt.lu

hello all. I have a 530i with a N53B engine, 2007 112,000km. Early this year it suddenly started to run really rough, missfiring etc. into the local main dealer, replaced all coils, plugs O2 sensors and injectors. Now its out of warranty and 3000km later and it starts to play up again. From a cold start it coughs and seems to missfire, after a fw mins running the car is perfect, great to drive. I was advised to get the codes so I did, missfire #4 & #6 no other codes, so 2 new coils, no change, so then I changed all coils and plugs. #2 plug was really black. also there was a tiny bit of oil on the white ceramic of the plug. so 6 coils & 6 plugs later, all original BMW parts. its better but still not right, no codes at all. cold start ticks over fine for a short while or until touching the throttle, then it hunts and seems to missfire, I can drive it but it coughs and splutters, at a standstill in neutral the revs go up and down when driving after maybe 2 to 3 mins maximum suddenly the fault dissapears and all is wonderfull.
If I stop and restart the engine when it is warm everything is fine (stop for gas etc). anybody have a guess at the cause of this? or seen it before? or can anybody tell me what tels the engine "OK you are warmed up now switch to warm running instead of cold start mode" or whatever it does ???

AchtungE60

Sounds like a vacuum leak. If you're having misfires though, you should really check the air intake, manifold and anything related in there. Sorry wish I knew more about your engine but this is very common on all cars. Camshaft position sensors can also have this effect.

stewart@pt.lu

Thanks, I will start to look there next. I should have mentioned, I also fitted a new MAF so that is ruled out...

pcy

Where did you buy that new MAF? Is that a genuine part?

stewart@pt.lu

Yeah, genuine article, VDO Siemens unit., identical to the one I removed.
The fault is just like in the good old days if you did not pull the choke all the way out. That's why I wonder what tells the engine it has warmed up

pjk0159

Stewart, I have an 07' 530i and have the same issue.

I had turned my car in for transmission problems, but the rumbling issue is one of the reasons why I turned it in as well.

If I learn anything new I'll keep you posted. In the meantime, it would be great if you can let us know too if you discovered a way to fix this.

L337E60

Wasn't the rumbling related to exhaust vibrations that was fixed by installing a modified exhaust bracket? There is a TSB somewhere...

L337E60

From a post in the "other" forum:

"Service Bulletin 18 02 08

Customer may complain of a slight vibration and/or droning noise when the vehicle is idling in park, neutral, drive and reverse when engine is at operating temperature.


CAUSE
Insufficient vibration dampening of the exhaust system.


PROCEDURE
1.Verify the complaint. Vibration/droning is most prevalent when engine is at operating temperature.

2.Remove the lower bracket for the exhaust system. If droning/vibration is gone, proceed to step three. If vibration/droning still exists with the lower bracket removed; continue troubleshooting exhaust/driveline for other causes or conditions

3.Remove complete bracket assembly and replace it with the bracket (1) PN 18 20 7 521 346 using two new ASA bolts (PN 07 12 9 905 417. Tighten to 21Nm.
Install front pipe bracket (1) PN 18 20 7 521 347 with four rubber bushings (2) (PN 18 20 7 546 579) to the new 346 bracket with two ASA bolts (PN 07 12 9 904 559) and two nuts (PN 07 12 9 904 580). Tighten down to 21Nm

4: Replace the stock 88Hz exhaust vibration dampener (1) with the 32hz dampener PN 18 10 7 506 145. Tighten to 21Nm.

After performing this procedure the vehicle will exhibit the same amount of normal driveline vibration as a comparably equipped E60 with a M54 or N52 engine."




Now what follows is the exact wording from the invoice of what the dealer did to repair my car:

“Insufficient vibration dampening of the exhaust system. As per service bulletin 18 02 08, verified vibration, removed lower bracket from exhaust system, vibration no longer present, removed and replaced complete exhaust bracket assembly and replaced exhaust vibration dampener, test drove vehicle OK. Defect Code: 18 11 00 39 00 Labor op: 18 99 000”

stewart@pt.lu

Thanks guys, for sure it's not exhaust rumble, this is missing. I found some mention of an idle control valve during a google search, just looking to see if I have such a thing and that will be next. Not sure when I will get the chance to investigate, heavy weekend coming up. I will of course let you know what I find.