Unstable rpm at idle

[Dackelone]

Go to your dealer and ask for this SIB to be performed:
SI B12 09 12...intermittent stalling lack of power N55

http://www.scribd.com/doc/151944423/...T-Stalling-TSB

[3rdgear]

Hey thanks Dackelone. Most of the time the rpm goes up and down only stalled on me twice. What does the sib do, is it a newer software. Does it work for n54 engines too

[Dackelone]

Originally Posted by 3rdgear

Hey thanks Dackelone. Most of the time the rpm goes up and down only stalled on me twice. What does the sib do, is it a newer software. Does it work for n54 engines too

Yes, its a new SW update. Uhh... you have a N54. ? No its not for that engine. I now see you have a 1M. Sorry this SIB will not work for that engine.


I would still check things like thrown codes, loose TDC sensor or the output signal of the sensor and for vacuum leaks(ie a leaking valve cover, oil cap, etc).

[3rdgear]

I don't understand Ian, if Cobb isn't installed, I'm only left with stock BMW map right or do you mean they all sucks

[3rdgear]

Oh yes, tks for the reminder. Have unmarried it already

[3rdgear]

Hi guys, after one month of testing the problem is still here, I have removed Cobb and Afe and returned to stock map and intake, tested for vacuum leak and checked for code at dealership along with fuel pump and every test came out fine. So the only mod I have left is the intercooler with ak mid and muffler plus the motul engine oil I had changed.
The car now runs fine but occasionally the rev will go up 500rpm and come down again, while I had Cobb, rev went even higher and it stalled a few times, so the problem has improved but it is still extremely ignoring especially when the dealer can't work on it without seeing any codes and I don't have any specialist I can count on in my area.
I'm totally stressed out as I must fix whatever it is before putting the Cobb and Afe back on, so guys if you have any ideas, plsssssssss help

[headsup7up]

try replacing the coil packs.

[frank35]

Make coding injectors and tell me later

[1swift1]

I had similar symptoms (low rpm that sounded as if it were just about to stall). I also had a low battery warning show up recently. Trickle charging while I was deployed apparently wasn't good enough. Also I have a very short drive to and from work.
Dealer changed the battery after testing it (and also changed an ISB cable). That was 2 weeks ago, and I haven't noticed any of the low RPM, near stalling type problems.
Good luck!

[crex]

I had the same problem on my 135i and I got the walnut blasting and It hasn't happened since.

[Jay-K]

this is only during idle right?
e.g. you are holding the rpm at 2000 and it goes up and down?

i had this before and later found out that the exhaust system create this, however since then i changed to akrapovic, and had bigger problems.. RPM's go low even when its not idle, but after few moments the engine self revved and the RPM go stable.

I would honestly say don't need to worry to much about this, cause last time a friend of mine said turbo engine does this..

good luck

[l888apex]

edit

[3rdgear]

Hey Jay yes self revving when gas padel isn't pressed. Tho it might not be dangerous but if I install Cobb, the problem becomes a lot worse to a point it will stall and it's very stressful not being able to fix it

[3rdgear]

Took my car for a thorough body check today and found the third injector to be quite dirty with water stain and took out some gas to see the quality which turned out to be black color almost. So the guys at the workshop reckon it's the bad gas causing the unstable rpm. So it's possible that Cobb has a higher gas quality requirement and it's more sensitive to bad gas that's when I stalled a few times while running their maps.
So conclusion is to find a better gas station offering cleaner gas which can be difficult in shanghai

[Jay-K]

Originally Posted by 3rdgear

Took my car for a thorough body check today and found the third injector to be quite dirty with water stain and took out some gas to see the quality which turned out to be black color almost. So the guys at the workshop reckon it's the bad gas causing the unstable rpm. So it's possible that Cobb has a higher gas quality requirement and it's more sensitive to bad gas that's when I stalled a few times while running their maps.
So conclusion is to find a better gas station offering cleaner gas which can be difficult in shanghai

Yup,
that's one of the dealer suggestions.
hence i was on stock map before,
my biggest guess for my issue was the carless down pipe or O2 sensors..
nevertheless it got sold before i manage to solve them

[mike@x-ph.com]

I have the same thing with JB4 no codes.
I got tired trying to figure out what's wrong so i just left it as is it has been 1 year no problem

[sutter2k]

Originally Posted by 3rdgear

I hope so too but the unstable rpm does seem to happen more often when I'm running Cobb map, both times I stalled was running their maps. Stock map still unstable but not as frequent

Mine is much worse on the cobb maps than the OEM mapping. I kind of have to run the cobb long term since I have RB turbos.