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Discussion Starter #1 (Edited)
Long story short: has anybody seen smg accumulators go bad? The few threads I've read seem to have solved nothing by changing them. Or has it?

Soooo... for the first time got a very short (wasn't even able to read the message) yellow cog about a month ago. Got a 4f40. Did the ista steps and found nothing. Reset it and didn't think much about it. Fast forward to this weekend, and on the highway I got a yellow followed by red cog and the car shifting into N. Fixed itself about 20 seconds later, while still coasting. Drove home without any further issues. Got 4f40 and 4f43 this time. Everything checks out BUT the accumulator. I remember running the test before as it was right at the limit (29bar). This time it's 28bar and it causes the test to fail. I doubt this would cause the error codes I'm getting tho. IMO it all points to the pump motor, but I'd rather troubleshoot rather than buy a new accumulator (since pump motors are in worldwide backorder anyway...). Motor sounds just like the 'good' ista clip. I timed how long the motor runs after sitting overnight: about 12.5 seconds. This would seem longer than the other thread, but with only these 2 values to compare I wouldn't call it bad.

Of course, this is after I changed to MTL, had a new slave/clutch installed, vanos, rod bearings, etc. Just as I think the car is driving (and shifting) the best I've ever seen it....
 

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Discussion Starter #2
Got an mp3/4 clip of the pump running this morning but audio uploads are disabled. Any idea how to post the clip?
 

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Try getbmwparts.com it is tisher in md. Everyone had them back oredered but they had them in stock

Sent from my SAMSUNG-SM-G900A using Tapatalk
 

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On opening the car in the morning just about all SMG pumps i have heard run on average 10 seconds. I have heard pumps with a special sound at times of failure.
 

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Turns out uploading an mp3 is not that straightforward. But here it is: how does others compare?

https://www.youtube.com/watch?v=LM38KVTBeTM
That sounds a little long to me - but I know that there is a difference between the "cold" pump prime and the 2nd pump prime, even if that priming is done later but with the car still cold. I'm going to be prepping the M5 for a new fan starting tonight, so I'll take the time to check out the pump priming length initially and later. There may be some tech challenges with a new phone (the old one had Youtube as a choice for videos) but I'll do my best.
 

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The overall run time sounds ok, but I don't like how the motor sounds at the end of the clip...Did you move your recording device closer?
 

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Discussion Starter #11 (Edited)
On the 'second' priming the pump runs for half the time, sounds at the end (before it shuts off) about the same.

So the accumulator test is passing again (29 bars - barely within range). But isn't lower better? The acceptable range is from 29 bar to 45(?). So if the accumulator drops all pressure at a higher value then it means it's bad, no?
 

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Yes, I've had accumulators fail before. Pressure won't reach target range, even after multiple bleeding attempts. The pump motor is obviously the more common culprit. The bracket that holds the motor in place wraps around the accumulator. Once that is free, you use a 17mm wrench on the end of the accumulator to spin it free.
 

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Discussion Starter #13
Yes, I've had accumulators fail before. Pressure won't reach target range, even after multiple bleeding attempts. The pump motor is obviously the more common culprit. The bracket that holds the motor in place wraps around the accumulator. Once that is free, you use a 17mm wrench on the end of the accumulator to spin it free.
Yeah seems straightforward to replace. Question is when they are bad, is the pre-pressure test value low or high?
 

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Here is a video of unlocking the car after it sat for a couple of days.

+ https://youtu.be/Jda99omW94U" title="View this video at YouTube in a new window or tab" target="_blank">YouTube Video
https://youtu.be/Jda99omW94U"> https://youtu.be/Jda99omW94U" /> ERROR: If you can see this, then YouTube is down or you don't have Flash installed.
 

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Discussion Starter #15
Here is a video of unlocking the car after it sat for a couple of days.

+ https://youtu.be/Jda99omW94U" title="View this video at YouTube in a new window or tab" target="_blank">YouTube Video
https://youtu.be/Jda99omW94U"> https://youtu.be/Jda99omW94U" /> ERROR: If you can see this, then YouTube is down or you don't have Flash installed.
Definitely shorter (about 8.4 seconds vs. 12.5 on mine). Pitch before it shuts off is also higher on yours. Is yours still on the original pump motor? Do you have ista/inpa to run the accumulator pre-pressure test?
 

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Definitely shorter (about 8.4 seconds vs. 12.5 on mine). Pitch before it shuts off is also higher on yours. Is yours still on the original pump motor? Do you have ista/inpa to run the accumulator pre-pressure test?

I don't know what has been done. I doubt very much that it is the original pump since this car is a cliche of hitting every bad spot on the maintenance tree. I have INPA and ISTA - prefer INPA for this. Where do I find the accumulator pre-pressure test... (assuming that it won't screw anything up - I do not want the red cog of death right now).
 

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Discussion Starter #17
Great, thanks. I'll look up the steps to run it in inpa. It is under the smg activate menu I believe. FYI my copy of inpa does not run the test, but yours might... ISta works fine on mine. This is a test; won't affect the adaptations so you'll be fine.
 

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Discussion Starter #19
On INPA go to the SMG module then
F6 activate
F4 M
F1
F1
Mine won't work but you may have better luck.

I'll post ISTA steps shortly...
 

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Discussion Starter #20
ISTA:
read vehicle out
from top menu select vehicle management
select troubleshooting
select function structure
select drive
select smg
select hyd unit
select hyd unit again
hit search
select option abl SMG hydraulic unit
hit next twice
select option 3 mechanical faults
select option 3 accumulator prepressure
follow prompts / hit next until test runs
 
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