Erratic rpms at start

1Hokie · 11-19-2015, 08:42 AM

So... When I start the car in the mornings things seem normal. But when I pop it in reverse it stutters and rpms bounce around and if I'm not careful or feed it extra gas it almost stalls. Doesn't do it if I go into first afterwards. Just reverse. Odd? Also my car has dropped into limp mode on the highway twice in the past month. Not even WOT or anything. Once while accelerating at maybe 3500 and another just cruising at 3k. New ignition cools and plugs. I'm thinking injectors now but before I shell out a bunch of dough I wanted to get some more thoughts. Pulled codes and once it was secondary air. Another time it said misfires

RoundelM3 · 11-20-2015, 08:12 AM

Could be the eccentric shaft sensor for the Valvetronic system. I just had this repair done to the wife's 128i at 40K miles after noticing erratic idle at cold start, surging at constant throttle, and lumpy idle/stalling when warmed up. Repair runs just under $1K including parts and labor at a good Indy shop.

1Hokie · 11-20-2015, 11:33 AM

Quote:

Originally Posted by roundel335

Could be the eccentric shaft sensor for the Valvetronic system. I just had this repair done to the wife's 128i at 40K miles after noticing erratic idle at cold start, surging at constant throttle, and lumpy idle/stalling when warmed up. Repair runs just under $1K including parts and labor at a good Indy shop.

Yeah. Bc that's inside the valve cover right. Damn. I just replaced the cover gasket too myself. Hated taking it apart

RoundelM3 · 11-21-2015, 07:55 AM

Quote:

Originally Posted by 1Hokie

Yeah. Bc that's inside the valve cover right. Damn. I just replaced the cover gasket too myself. Hated taking it apart

Yep, that's where it is. There's actually a DIY for the procedure on this forum. There's also another internal gasket/seal required for the sensor removal/replacement. Sometimes this seal fails, allowing oil to seep in and cause the sensor to fail. The shop I used had done this repair before, had all the tools, and they guarantee their work, so I decided it was worth paying them rather than tackling it myself.

ryanSTL · 01-26-2016, 08:46 PM

i assume you're getting a check engine light? my 2008 128 convertible is having the exact same problem. rough idle on cold start. car hesitates & stalls going in reverse. it seems to drive OK in forward gears, but you can tell the car isn't right.

I had an independent shop look at it this morning and they told me the car is throwing VANOS codes. They mentioned some sort of engine flush and cleaning or replacing of sensors. I haven't researched this issue until tonight and wondering if you've found anything out about your car and/or had it fixed since this post?

thanks

RoundelM3 · 01-27-2016, 08:19 AM

There is a known problem with broken VANOS bolts that BMW has issued a recall/extended warranty on, but nothing for the Valvetronic sensor problem that I had. I'm not sure what an "engine flush" consists of, but they may be referring to making sure there's no sludge in either of these valve-control mechanisms. If you're getting VANOS codes and not any referring to "eccentric shaft sensor", then it may be that the bolts need replacing. While they're in there, though, it might not be a bad idea to have the eccentric shaft sensor replaced as well to prevent having to do it later on.

1Hokie · 01-27-2016, 11:30 AM

So I had my car taken in for a bunch of work from the dealership since mine falls under the SULEV warranty and turns out it was a combination of secondary air pump failing and 2nd exhaust manifold being faulty. one or both were causing rough reverse rpms and misfires and such.

11-19-2015, 08:42 AM	#1
1Hokie Banned 24 Rep 242 Posts Drives: 08 328i, 10 z4 35i Join Date: Jun 2015 Location: crystal city iTrader: (2) Garage List 2008 BMW 328i E92 [0.00] 2010 BMW Z4 sDrive35i [7.00]	Erratic rpms at start So... When I start the car in the mornings things seem normal. But when I pop it in reverse it stutters and rpms bounce around and if I'm not careful or feed it extra gas it almost stalls. Doesn't do it if I go into first afterwards. Just reverse. Odd? Also my car has dropped into limp mode on the highway twice in the past month. Not even WOT or anything. Once while accelerating at maybe 3500 and another just cruising at 3k. New ignition cools and plugs. I'm thinking injectors now but before I shell out a bunch of dough I wanted to get some more thoughts. Pulled codes and once it was secondary air. Another time it said misfires
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11-20-2015, 08:12 AM	#2
RoundelM3 Major General 1833 Rep 6,986 Posts Drives: 15 F80 M3, 22 G01 X3 30i Join Date: Apr 2010 Location: Wendell, NC iTrader: (2) Garage List 2022 BMW X3 [9.83] 2015 BMW M3 [6.50]	Could be the eccentric shaft sensor for the Valvetronic system. I just had this repair done to the wife's 128i at 40K miles after noticing erratic idle at cold start, surging at constant throttle, and lumpy idle/stalling when warmed up. Repair runs just under $1K including parts and labor at a good Indy shop. __________________ 2015 F80 ///M3 Sedan 7DCT Tanzanite, 2022 X3 sDrive30i 8AT Brooklyn Grey
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01-26-2016, 08:46 PM	#5
ryanSTL First Lieutenant 116 Rep 347 Posts Drives: '15 435GC rwd Join Date: Mar 2014 Location: St. Louis iTrader: (0)	i assume you're getting a check engine light? my 2008 128 convertible is having the exact same problem. rough idle on cold start. car hesitates & stalls going in reverse. it seems to drive OK in forward gears, but you can tell the car isn't right. I had an independent shop look at it this morning and they told me the car is throwing VANOS codes. They mentioned some sort of engine flush and cleaning or replacing of sensors. I haven't researched this issue until tonight and wondering if you've found anything out about your car and/or had it fixed since this post? thanks
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01-27-2016, 08:19 AM	#6
RoundelM3 Major General 1833 Rep 6,986 Posts Drives: 15 F80 M3, 22 G01 X3 30i Join Date: Apr 2010 Location: Wendell, NC iTrader: (2) Garage List 2022 BMW X3 [9.83] 2015 BMW M3 [6.50]	There is a known problem with broken VANOS bolts that BMW has issued a recall/extended warranty on, but nothing for the Valvetronic sensor problem that I had. I'm not sure what an "engine flush" consists of, but they may be referring to making sure there's no sludge in either of these valve-control mechanisms. If you're getting VANOS codes and not any referring to "eccentric shaft sensor", then it may be that the bolts need replacing. While they're in there, though, it might not be a bad idea to have the eccentric shaft sensor replaced as well to prevent having to do it later on. __________________ 2015 F80 ///M3 Sedan 7DCT Tanzanite, 2022 X3 sDrive30i 8AT Brooklyn Grey
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01-27-2016, 11:30 AM	#7
1Hokie Banned 24 Rep 242 Posts Drives: 08 328i, 10 z4 35i Join Date: Jun 2015 Location: crystal city iTrader: (2) Garage List 2008 BMW 328i E92 [0.00] 2010 BMW Z4 sDrive35i [7.00]	So I had my car taken in for a bunch of work from the dealership since mine falls under the SULEV warranty and turns out it was a combination of secondary air pump failing and 2nd exhaust manifold being faulty. one or both were causing rough reverse rpms and misfires and such.
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