Trouble Shooting 29DC Code

joyride · 04-27-2014, 11:26 AM

Hey Guys, just want to put this out there to see if anyone see's anything else.

Car has been stumbling under higher loads. Started at the Track and has been getting worse ever since. 3 - 6 gear, under light or hard throttle input, can feel the car stumble.

Car has been throwing 29DC codes, sometimes get CEL, other times, it just does the normal car shaking feels/sounds like it's running on -1 cylinder. Stop/Restart and runs normal.

I've replace spark plugs and coils - they were pretty old anyways.

My further research has pointed to a lot of info saying it's LPFP or LPF Sensor.

Looking at the datalog, you can see the the LPFP drop, but also the HPFP drop extremely. Does this seem cause and effect? I'm leaning towards the higher upstream problem, causing the issues down stream.

I've got a new LPFP and LPF Sensor in hand, going to swap out the LPFP first and then take a look at the logs. Does anyone else see anything crazy I should worry about? If the HPFP still has issues, I should be able to get that done under the ext. warranty.

http://datazap.me/u/joyride/lpfp-335...mark=1800-1974

Sorry about the long datalog, i zoomed into the 2nd gear pull and marked it at 1800-1974.

Thanks guys!!!

joyride · 04-28-2014, 01:34 PM

Added the LPFP - didn't really help anything. Going to put in the new LPF Sensor to verify.

http://datazap.me/u/joyride/lpfp-335...mark=2508-2724

If the LPF Sensor doesn't help at all, it's looking like it's the HPFP. Looking at the datalog. You can see where the HPFP pressure takes a nose dive and gets as low as 150PSI. The requested is high, so it doesn't seem like a controller, more like issue with the pump itself.

Question, has anyone datalogged a bad HPFP and then had the Dealer do their tests to verify and swap it out under the extended HPFP warranty?

It's throwing the 29DC, and depending on how hard I want to push it, i can get the CEL. But trying to push it thru the stumbling just goes against my nature, clearing he's having trouble.

joyride · 05-09-2014, 06:35 PM

Just wanted to put a quick update for anyone else trouble shooting.

Replaced LFP Sensor - still having issues, so IMO all signs are pointing to the HPFP.

The logs are clearly showing that the HPFP isn't keeping up with requested PSI and quickly dropping under load.

Took car to dealer to have them diagnose and do the HPFP test.

Got the call today, sure enough, HPFP failed and replaced under the 10yr/120mile warranty. I'll do a datalog to show the difference between my failing and hopefully solved HPFP fueling issues.

MatrixE93 · 05-09-2014, 07:06 PM

Glad I saw your thread, my car has the same issues as you and I just replaced the plugs and coils. Looks like I'll be making a trip to the dealer next week for a hpfp
http://www.e90post.com/forums/showthread.php?t=983191

e90Mark · 05-09-2014, 07:20 PM

Wow, this is really weird..

Check my thread. Pretty sure I have the same problem, @MatrixE93..

http://www.e90post.com/forums/showthread.php?t=983249

My car is going to the dealer tomorrow, but it was for a different service. Gonna let them know about a possible HPFP problem.. Still on factory AFAIK.

04-27-2014, 11:26 AM	#1
joyride Second Lieutenant 43 Rep 231 Posts Drives: X5 M-Sport Join Date: Mar 2008 Location: Detroit iTrader: (2)	Trouble Shooting 29DC Code Hey Guys, just want to put this out there to see if anyone see's anything else. Car has been stumbling under higher loads. Started at the Track and has been getting worse ever since. 3 - 6 gear, under light or hard throttle input, can feel the car stumble. Car has been throwing 29DC codes, sometimes get CEL, other times, it just does the normal car shaking feels/sounds like it's running on -1 cylinder. Stop/Restart and runs normal. I've replace spark plugs and coils - they were pretty old anyways. My further research has pointed to a lot of info saying it's LPFP or LPF Sensor. Looking at the datalog, you can see the the LPFP drop, but also the HPFP drop extremely. Does this seem cause and effect? I'm leaning towards the higher upstream problem, causing the issues down stream. I've got a new LPFP and LPF Sensor in hand, going to swap out the LPFP first and then take a look at the logs. Does anyone else see anything crazy I should worry about? If the HPFP still has issues, I should be able to get that done under the ext. warranty. http://datazap.me/u/joyride/lpfp-335...mark=1800-1974 Sorry about the long datalog, i zoomed into the 2nd gear pull and marked it at 1800-1974. Thanks guys!!!
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04-28-2014, 01:34 PM	#2
joyride Second Lieutenant 43 Rep 231 Posts Drives: X5 M-Sport Join Date: Mar 2008 Location: Detroit iTrader: (2)	Added the LPFP - didn't really help anything. Going to put in the new LPF Sensor to verify. http://datazap.me/u/joyride/lpfp-335...mark=2508-2724 If the LPF Sensor doesn't help at all, it's looking like it's the HPFP. Looking at the datalog. You can see where the HPFP pressure takes a nose dive and gets as low as 150PSI. The requested is high, so it doesn't seem like a controller, more like issue with the pump itself. Question, has anyone datalogged a bad HPFP and then had the Dealer do their tests to verify and swap it out under the extended HPFP warranty? It's throwing the 29DC, and depending on how hard I want to push it, i can get the CEL. But trying to push it thru the stumbling just goes against my nature, clearing he's having trouble.
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05-09-2014, 06:35 PM	#3
joyride Second Lieutenant 43 Rep 231 Posts Drives: X5 M-Sport Join Date: Mar 2008 Location: Detroit iTrader: (2)	Just wanted to put a quick update for anyone else trouble shooting. Replaced LFP Sensor - still having issues, so IMO all signs are pointing to the HPFP. The logs are clearly showing that the HPFP isn't keeping up with requested PSI and quickly dropping under load. Took car to dealer to have them diagnose and do the HPFP test. Got the call today, sure enough, HPFP failed and replaced under the 10yr/120mile warranty. I'll do a datalog to show the difference between my failing and hopefully solved HPFP fueling issues.
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05-09-2014, 07:06 PM	#4
MatrixE93 Enlisted Member 17 Rep 48 Posts Drives: 2009 E93 MT Join Date: Sep 2013 Location: Pittsburgh iTrader: (0)	Glad I saw your thread, my car has the same issues as you and I just replaced the plugs and coils. Looks like I'll be making a trip to the dealer next week for a hpfp http://www.e90post.com/forums/showthread.php?t=983191
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05-09-2014, 07:20 PM	#5
e90Mark Captain 31 Rep 722 Posts Drives: 2008 BMW 335xi Join Date: Aug 2013 Location: Detroit iTrader: (5) Garage List 2008 BMW 335xi [10.00]	Wow, this is really weird.. Check my thread. Pretty sure I have the same problem, @MatrixE93.. http://www.e90post.com/forums/showthread.php?t=983249 My car is going to the dealer tomorrow, but it was for a different service. Gonna let them know about a possible HPFP problem.. Still on factory AFAIK.
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