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Discussion Starter #1
2009 535i xDrive; engine N54(B30)

When I accelerate from ~45 mph to just above 65mph (when entering onto a major highway), on many occasions there is engine shake. I believe it's engine shake (no shimmy of steering, etc.), almost like the engine has bad supports! (hard to explain) However, at other times there is no shake at all even going up to 85 mph or higher. The shaking is not violent or uncontrollable, but clearly this is not good.

I recently got the dreaded "low pressure fuel pump failure" message. Based on codes (using BMWhat), indication of fuel sensor failure and/or fuel pump failure. I have replaced the fuel sensor and the associated codes are not reappearing (after clears). Car generally is running fine if consistently below 55 mph and without hard acceleration.

Some background on car's maintenance:
Castrol synthetic oil changed 4k miles ago
Air filter changed 2 weeks ago
Using 92 or 93 octane gas; also, "Techron concentrate plus" just to clean-up any gunk
Tire pressure is checked and is holding fine
Tire has 80+% tread; was balanced 6 months ago

I am going to borrow (from Autozone) the "Actron CP9920A" and check the fuel pressure to see if that may be causing this ... I am hoping it's not the fuel pump that's bad. If so, I have to open up the fuel tank under the rear seat! PITA.

Next to do: change spark plugs, since I have no idea when the PO changed the spark plugs.

Any other thoughts?

On a separate, but unrelated note, I am getting "excessive battery discharge" message. The battery had drained down quite a bit (below 12V). I have since charged the battery (full, then trickle) and it's now fully charged (showing 12.7V not charging and 14.1V charging at idle). This issue seems be reported for this model without a clear solution? I have since shut down everything manually (even the AC or radio) before shutting down the car. I am also locking the car just to be sure all is quiet.

The message still appears occasionally, especially after the car is sitting idle overnight (so, something is still consuming ... "alive"?)

Note: the IBS is currently disconnected, as I want to observe the symptom/issue without having to deal with (potentially) faulty IBS circuitry.
 

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At what RPM range does this occur? If you hold the transmission in a lower gear do you get the shake at lower speeds at the same RPMs? If it is speed related and not RPM related you most likely have a suspension or wheel/tire issue; if RPM related it could be motor mounts, ignition coils, fuel feed related or various other items.
 

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actually - I'd hope it was HPFP - they're on extended warranty... you could get another fuel pump and labor handled for free because they have been a problem for everyone.. :D
 

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Discussion Starter #6
actually - I'd hope it was HPFP - they're on extended warranty... you could get another fuel pump and labor handled for free because they have been a problem for everyone.. :D
I had taken it to the dealer, they charged me for the "diagnostics" (simple OBD connection I am sure) and informed me the fuel sensor AND fuel pump needs to be replaced. $2k!! HPFP failure codes didn't show up, so they clearly didn't want to do that work. Now that I have the BMWhat, I can do the diag and also programming (very handy tool)!

I did replace the fuel (low) pressure sensor and the associated codes are gone. Of course, it's entirely possible that HPFP might show up again ... and I also hope it does!
 

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Discussion Starter #7 (Edited)
on the battery - if it's original, then it's probably due to be replaced anyway. I did mine after faffing around a load with charges and it just wouldn't hold - I wished I'd done it months earlier. The autozone duralast gold is what I put in - not had an electrical issue since! :D
my 09 535xi took the H8-DLG:

http://www.autozone.com/batteries-s...t-gold-battery/832331_682373_0/?checkfit=true
Save
I didn't check the date code on the battery, which is what I will do now!
thanks.
 

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Discussion Starter #8
Shake test

I did few tests today and here are the observations:

  1. Shake consistently comes up just around 65 mph and seems to be independent of RPM at that speed. In other words, I could be cruising up to 65 and either at 2k rpm or 3-4k rpm (later being a bit spirited) - the behavior doesn't change.
  2. Severity of shake appears to be lesser when going up an incline (say 15 degree). In other words the shake is more severe when going down hill (a bit strange).
  3. If I go up to 75 mph (through shake at 65 mph) and then let it coast down (foot off gas) the shake continues until speed comes down below 60 mph. So, the shake definitely seems speed related.
  4. On very hard acceleration from about 40 mph, the shake does come up occasionally even below 65mph, but that's not common.
  5. during the shake, the car feels as if it's "knocking", but that could be my imagination ... I am using 92 or 93 octane, so knock shouldn't be an issue.

I am getting this error code (after previous reset).

Motor Control:
Engine / Motor
Fault: :engine turn-off time / Ignition timing at idle, cold start: firing angle too early /
Motorabstellzeitermittlung
Code: 2F83
Fault: :Motorabstellzeitermittlung / engine turn-off time
Code: 2F81

I am suspecting these codes have something to do with the shake, but I don't know what's causing it.

Next to-do:
- replace spark plugs (due anyway)
- check spark plug boots for cracks, etc. (replace as needed)
- check fuel pressure (on injector rail) at Autozone

Any other suggestions?
 

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Discussion Starter #9
btw. I haven't seen a code that would indicate a HPFP failure ... that would have solved the mystery!
 

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I did few tests today and here are the observations:

  1. Shake consistently comes up just around 65 mph and seems to be independent of RPM at that speed. In other words, I could be cruising up to 65 and either at 2k rpm or 3-4k rpm (later being a bit spirited) - the behavior doesn't change.
  2. Severity of shake appears to be lesser when going up an incline (say 15 degree). In other words the shake is more severe when going down hill (a bit strange).
  3. If I go up to 75 mph (through shake at 65 mph) and then let it coast down (foot off gas) the shake continues until speed comes down below 60 mph. So, the shake definitely seems speed related.
  4. On very hard acceleration from about 40 mph, the shake does come up occasionally even below 65mph, but that's not common.
  5. during the shake, the car feels as if it's "knocking", but that could be my imagination ... I am using 92 or 93 octane, so knock shouldn't be an issue.

I am getting this error code (after previous reset).

Motor Control:
Engine / Motor
Fault: :engine turn-off time / Ignition timing at idle, cold start: firing angle too early /
Motorabstellzeitermittlung
Code: 2F83
Fault: :Motorabstellzeitermittlung / engine turn-off time
Code: 2F81

I am suspecting these codes have something to do with the shake, but I don't know what's causing it.

Next to-do:
- replace spark plugs (due anyway)
- check spark plug boots for cracks, etc. (replace as needed)
- check fuel pressure (on injector rail) at Autozone

Any other suggestions?
Have all of your suspension components, the drivetrain and motor mounts checked.
 

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Discussion Starter #11
Update on LPFP

I have an update, but an unsuccessful one.

I just replaced the low pressure fuel pump (inside tank, under rear seat), but I am still getting a "fuel pump" failure message! The car went into limp mode and I was lucky to get immediately to side of of hi-way. It took several attempts of trying/waiting before the car started again (much hesitation ...) and was able to drive home (3 miles with flashers on).

Background:
- I had replaced the fuel pressure sensor (inside engine compartment, that's for measuring fuel pressure coming in before the high pressure fuel pump (HPFP)); this was to deal with the LPFP sensor fault - that fault is gone. Now, I replaced the fuel pump assembly (entire one from passenger side to driver side tubes and all.)

I recently was able to request for a VIN based service record from the dealer I bought the car from. That shows that the HPFP and the injectors were already replaced once!! That's the good and bad news ...

Why am I again getting fuel pump failure message? I am suspecting the HPFP is not quite working ... this seems like a recurring issue; fortunately, it's still under BMW extended warranty (voluntary!?).

Time for more diagnosis.
I am going to drive the car again and check for any fault codes using Carly for BMW WIFI
 
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