hard acceleration: pop -> awd/dsc/dbc/start-off an idle surge up and down

borisivan · 07-20-2018, 05:47 PM

Hi,

2010 335xi 159k miles, MT.

Was at a busy intersection forever, waiting to turn left. Finally, the planets align and there is a small gap of traffic in both directions.

Turned DSC off, as I was going to be punching it and turning left, didn't want traction control to kick in and slow me down in the middle of the 2 way traffic.

Put it in 1st, punched it, 2nd, accelerating hard.. didn't get anywhere close to red line, but was under a ton of load. Probably ~ 5-6k RPM, nothing crazy... "POP" almost like a backfire, but not really sure where the sound came from.

Instant christmas tree worth of error codes and limp mode, pulled over right away.

In addition to the limp codes, the idle is surging up and down. Start the car fresh and the idle jumps up to ~ 3k or more and then bounces up and down about once a second.

Had it towed, didn't get a chance to grab codes.

But from the screen:

AWD and DSC malfunction!
DBC malfunction! Drive carefully
Start-off assistance inactive!

Tried a few searches and found some hits regarding potential throttle body problems, but not sure. Other threads involved a battery problem, which seems doubtful. I replaced the battery a few years ago, and the problem happened immediately with the 'pop' under heavy load, something 'went'.

Thoughts?

marcvtec · 07-20-2018, 06:01 PM

Yup,

first thought is check your intake charge pipe where it connects to the throttle body.
It probably cracked and fell off.
Time for a new ER charge pipe.

Emilime75 · 07-22-2018, 10:59 AM

Very similar thing happened to me, except I was on the interstate. Have a thread about it here, somewhere. Charge pipe blew up under heavy load, Xmas tree in the cluster, idle RPM bouncing between 500-1500. Was able to slip the "crack" pipe back on and the clip sort of engaged. Luckily, had my ELM327 OBD-BT adapter, and cleared codes using the Torque App right there on the side of the highway. Lights on dash went away, idle back to normal, milked it the remaining 5 miles home. Replaced with aluminum charge pipe and all has been well since.

borisivan · 07-22-2018, 06:19 PM

Thanks guys, hoping that's what it is, as I assume that most alternatives would be worse.

It was towed to the dealership, will let you know what I hear.

I suppose towing to an indy would have been a better decision.. I need to get the upgraded service from AAA that allows for up to 100 miles towing. Dealership was 4 miles "over" the allotted miles, indy would have been much further. I'm guessing it would have still saved my a bunch of $ in the long run, as a better aftermarket pipe and labor would be a bunch cheaper than the OEM plastic one and dealer labor.

Assuming that's what the problem is, of course.

marcvtec · 07-22-2018, 08:49 PM

Let us know what the dealer says, I'm curious.

borisivan · 07-23-2018, 01:52 PM

broken charge pipe, as you suspected.

They didn't have part on hand, ordering and arriving+installing tomorrow. Don't remember the exact quote but around 600 total for parts+diagnostic+labor.

Wish I had the balls to have had it towed home instead, I've watched the videos and it doesn't look difficult at all. I even have the BT cable to clear the codes, etc.

Or, have paid the extra $ to had it towed to my indy, and I could have supplied a better replacement charge pipe, and had it all out the door for half the price, though paid an extra $40-50 in towing overage.

Hindsight, it's a wonderful thing.

I know it's silly, but I certainly like hearing the dealership confirm it's the least of my fears instead of something unexpected and much worse. Makes the $600 bill (which should be $300 with a better pipe at the indy or my house) MUCH MUCH easier to swallow.

When they call tomorrow and tell me "well we fixed the charge pipe... but....", I'll let you know.

Thanks for your help guys, appreciate it.

07-20-2018, 05:47 PM	#1
borisivan craptastic 21 Rep 281 Posts Drives: 2010 335xi Join Date: Jul 2007 Location: hell in a handbasket iTrader: (0)	hard acceleration: pop -> awd/dsc/dbc/start-off an idle surge up and down Hi, 2010 335xi 159k miles, MT. Was at a busy intersection forever, waiting to turn left. Finally, the planets align and there is a small gap of traffic in both directions. Turned DSC off, as I was going to be punching it and turning left, didn't want traction control to kick in and slow me down in the middle of the 2 way traffic. Put it in 1st, punched it, 2nd, accelerating hard.. didn't get anywhere close to red line, but was under a ton of load. Probably ~ 5-6k RPM, nothing crazy... "POP" almost like a backfire, but not really sure where the sound came from. Instant christmas tree worth of error codes and limp mode, pulled over right away. In addition to the limp codes, the idle is surging up and down. Start the car fresh and the idle jumps up to ~ 3k or more and then bounces up and down about once a second. Had it towed, didn't get a chance to grab codes. But from the screen: AWD and DSC malfunction! DBC malfunction! Drive carefully Start-off assistance inactive! Tried a few searches and found some hits regarding potential throttle body problems, but not sure. Other threads involved a battery problem, which seems doubtful. I replaced the battery a few years ago, and the problem happened immediately with the 'pop' under heavy load, something 'went'. Thoughts?
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07-20-2018, 06:01 PM	#2
marcvtec Banned 411 Rep 2,703 Posts Drives: M5 Join Date: Oct 2006 Location: toronto iTrader: (0)	Yup, first thought is check your intake charge pipe where it connects to the throttle body. It probably cracked and fell off. Time for a new ER charge pipe. Last edited by marcvtec; 07-20-2018 at 06:07 PM..
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07-22-2018, 10:59 AM	#3
Emilime75 Colonel 1227 Rep 2,476 Posts Drives: 2010 335i E92 LeMans Blue Join Date: Dec 2017 Location: Merica! iTrader: (1)	Very similar thing happened to me, except I was on the interstate. Have a thread about it here, somewhere. Charge pipe blew up under heavy load, Xmas tree in the cluster, idle RPM bouncing between 500-1500. Was able to slip the "crack" pipe back on and the clip sort of engaged. Luckily, had my ELM327 OBD-BT adapter, and cleared codes using the Torque App right there on the side of the highway. Lights on dash went away, idle back to normal, milked it the remaining 5 miles home. Replaced with aluminum charge pipe and all has been well since.
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07-22-2018, 06:19 PM	#4
borisivan craptastic 21 Rep 281 Posts Drives: 2010 335xi Join Date: Jul 2007 Location: hell in a handbasket iTrader: (0)	Thanks guys, hoping that's what it is, as I assume that most alternatives would be worse. It was towed to the dealership, will let you know what I hear. I suppose towing to an indy would have been a better decision.. I need to get the upgraded service from AAA that allows for up to 100 miles towing. Dealership was 4 miles "over" the allotted miles, indy would have been much further. I'm guessing it would have still saved my a bunch of $ in the long run, as a better aftermarket pipe and labor would be a bunch cheaper than the OEM plastic one and dealer labor. Assuming that's what the problem is, of course.
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07-22-2018, 08:49 PM	#5
marcvtec Banned 411 Rep 2,703 Posts Drives: M5 Join Date: Oct 2006 Location: toronto iTrader: (0)	Let us know what the dealer says, I'm curious.
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07-23-2018, 01:52 PM	#6
borisivan craptastic 21 Rep 281 Posts Drives: 2010 335xi Join Date: Jul 2007 Location: hell in a handbasket iTrader: (0)	ayep broken charge pipe, as you suspected. They didn't have part on hand, ordering and arriving+installing tomorrow. Don't remember the exact quote but around 600 total for parts+diagnostic+labor. Wish I had the balls to have had it towed home instead, I've watched the videos and it doesn't look difficult at all. I even have the BT cable to clear the codes, etc. Or, have paid the extra $ to had it towed to my indy, and I could have supplied a better replacement charge pipe, and had it all out the door for half the price, though paid an extra $40-50 in towing overage. Hindsight, it's a wonderful thing. I know it's silly, but I certainly like hearing the dealership confirm it's the least of my fears instead of something unexpected and much worse. Makes the $600 bill (which should be $300 with a better pipe at the indy or my house) MUCH MUCH easier to swallow. When they call tomorrow and tell me "well we fixed the charge pipe... but....", I'll let you know. Thanks for your help guys, appreciate it.
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