rpm drop on initial start-up

[Swimjim]

hi all:
this just started happening last week. on the first start-up of the day, the engine needs a little longer to fire up and when it does, the rpm drops to near stall. ideas?

vehicle is 2008 128i sport, 85000 miles, all original. could this be a battery issue? fuel pump or filter?

but it only happens on the first start of the day... no other time.

thanks

[fs88]

did you ever get this figure out?

I had similar issue on my 2012 with N51 engine (only 20k miles). At beginning of the day when I stop at the red light, I get rough idling. Not to the point of stalling....until this past weekend at 7 eleven after a long 2 hr drive...it stalls on me at start 10x. Had to call Roadside Assistance. But when they got to me (about 30-45 min), we were able to start the car with no problem.

I took it to dealership by work the next day. They are changing my fuel pump. Hope that would fix the problem.

p.s. Below are some related issue I found. Also forwarded to my Service Adviser.

"For the longest time I had a rough idle on my 2008 SULEV 328i, N51B30. I looked into all kinds of possible issues but wasn't able to diagnose the issue. If you're driving along and come to a stop, the idle would settle in, but the rpm would bounce by 2-300 rpm randomly and intermittently. Needless to say, there were unpleasant vibrations and noises when this happened. This was happening when the car was still under warranty at 30000 mi, and the dealer tried a few things but nothing worked (there was no fault code or SES light). They finally ended up increasing the idle speed to 650 rpm at my request so that the unpleasant vibrations would at least be minimized, but the problem continued. I contemplated getting the intake valves blasted but realized that would be useless on a Port Fuel Injected engine like the N51/N52."

http://www.e90post.com/forums/showthread.php?t=778082


http://www.e90post.com/forums/showth...1#post16726430

[chris82]

Originally Posted by fs88

did you ever get this figure out?

I had similar issue on my 2012 with N51 engine (only 20k miles). At beginning of the day when I stop at the red light, I get rough idling. Not to the point of stalling....until this past weekend at 7 eleven after a long 2 hr drive...it stalls on me at start 10x. Had to call Roadside Assistance. But when they got to me (about 30-45 min), we were able to start the car with no problem.

I took it to dealership by work the next day. They are changing my fuel pump. Hope that would fix the problem.

p.s. Below are some related issue I found. Also forwarded to my Service Adviser.

"For the longest time I had a rough idle on my 2008 SULEV 328i, N51B30. I looked into all kinds of possible issues but wasn't able to diagnose the issue. If you're driving along and come to a stop, the idle would settle in, but the rpm would bounce by 2-300 rpm randomly and intermittently. Needless to say, there were unpleasant vibrations and noises when this happened. This was happening when the car was still under warranty at 30000 mi, and the dealer tried a few things but nothing worked (there was no fault code or SES light). They finally ended up increasing the idle speed to 650 rpm at my request so that the unpleasant vibrations would at least be minimized, but the problem continued. I contemplated getting the intake valves blasted but realized that would be useless on a Port Fuel Injected engine like the N51/N52."

http://www.e90post.com/forums/showthread.php?t=778082


http://www.e90post.com/forums/showth...1#post16726430

They can just up the idle RPM up like that? I can see myself taking advantage of that. Cold start, EVERY start lol

[RoundelM3]

Valvetronic eccentric shaft sensor...having this problem now, getting repair estimates. RPM stumbles at idle, then surges at steady throttle while cruising. The eccentric shaft sensor goes bad mainly due to oil seeping into it past the seal, requiring replacement of the sensor, seal, and valve cover gasket. 6 months out of warranty, and one shop gave estimate of $1425 which included a new valve cover, which they say "is plastic and can warp over time, needs replacement to guarantee no leaks". All the repair articles and videos do not show valve cover replacement (part and gaskets is ~$355-$425). OP's problem may indeed be fuel pump, but checking codes, I found 2A31, which is the eccentric shaft sensor fault.

[RoundelM3]

Got estimates yesterday for replacing eccentric shaft sensor, seal, valve cover gasket and bolts:

BMW Dealership: $1590
Local Indy Shop: $979

Guess which one I'm going with!

[bNks334]

Do you guys have the latest software?

I was having this issue on my 2013 N51 and an update by the dealer solved my rpm fluctuations.

[RoundelM3]

Ours has the latest software as of March of this year. It's also an N52, and the software would likely not be the same as that of an N51. That aside, were you getting 2A31 fault code? That indicates a fault with the sensor, although oil can seep into the connector and cause false signals, but by then the damage to the sensor is already done. I've researched this extensively and it's a known problem, so I'm going to contact BMW of North America to see if they'll cover all or part of this repair. A component like this should not fail at 40K miles, especially if the car has been maintained carefully by BMW dealerships all through its warranty period. It's been driven less than 10K miles per year, mostly by my wife, and has never been abused in any way.

[Swimjim]

update... i have not had any issues with car since the post was started. i am not sure if it was a "cold weather" issue, but no problems.

since the posted was started, i did have the ecu flashed with an AA tune... did that "fix" it? i dont know.

[RoundelM3]

Brought the 128 in yesterday morning to an Indy shop in Wilmington, got it back last evening. Came in under budget ($914), problem gone, great customer service, everyone's happy! Anyone in the Wilmington area looking for a great Indy shop for their BMW, PM me for details.

Meanwhile, still no word from BMW USA about financial assistance on this premature repair. Will keep everyone posted once I am in communication with them.

[NIB]

Originally Posted by roundel335

Valvetronic eccentric shaft sensor...having this problem now, getting repair estimates. RPM stumbles at idle, then surges at steady throttle while cruising. The eccentric shaft sensor goes bad mainly due to oil seeping into it past the seal, requiring replacement of the sensor, seal, and valve cover gasket. 6 months out of warranty, and one shop gave estimate of $1425 which included a new valve cover, which they say "is plastic and can warp over time, needs replacement to guarantee no leaks". All the repair articles and videos do not show valve cover replacement (part and gaskets is ~$355-$425). OP's problem may indeed be fuel pump, but checking codes, I found 2A31, which is the eccentric shaft sensor fault.

Mine 128i with 37,500km was averaging 7.9km/l and I entered a pothole at speed, the Check engine, ABS, brake light and DTC light came on and I took it to mine Mechanic. Diagnosis was carried out and I was told to change the rear left wheel ABS Speed sensor, the Ignition coil and Plug and do an alignment after. All this has been done with stock parts. When put under the OBD2 Machine with intent to clear the error, it was still giving the following codes, 94C2, 94C7 and 5DB6. I have not done the alignment yet. Please what are the meaning of the fault codes.

[RoundelM3]

I don't have access to a list of codes, but I have a feeling that those you list may be something to do with the steering angle sensor. This would be affected if you hit a pothole at speed. I had one go bad on my previous car (2007 335i) and it was replaced, which then required coding by the dealership.