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Discussion Starter · #1 ·
Hey all,

Troubleshooting my GFs I3, MY15 with 54k on the clock. Over the last 5k miles the drive unit has been progressively getting louder. No unusual noises aside from the typical electric sound until last week where the car ended up "not going into gear" with a drivetrain malfunction message displayed on the IC. Advised my GF to lock the car and step away for a few minutes at which point the car went into gear and she limped it home. The drive unit now makes a distinct bad bearing sound when moving, it seems to be louder at low speed and gets smoother with speed.

I pulled the codes using a generic reader and got p1e90,p1e91,p0a42,p0a40,p0a3f, which indicate drive motor position issues, low and high circuit along with some inverter over voltage issues. Got ISTA installed and made myself an ENET cable so I will run through the proper diagnostic in the next day or two.

I searched around and it seems there are a few reports on drive unit failures which were mostly handled by the dealer by replacing the whole unit; It seems a new drive unit is around 4kUSD, ~2kUSD for a used one. I would like to explore the feasibility of doing this myself and have some questions:

  • Has anybody explored the idea of rebuilding the drive unit? It seems the drive unit is specific to the I3/I8 line and is referred by BMW as a HSM, Is there any mention who the OEM manufacturer is? Are there any companies rebuilding these motors? Are there any OEM manuals for these motors, workshop service manuals etc?
  • Has anybody opened these? What does it take? Do you need a press jig or any other specific equipment? The drive unit seems to be an all in one unit, with transmission/diff included as part of an assembly, is the position sensor located on the transfer case output or internally prior to the differential unit?
  • I reviewed the procedures in ISTA and feel fairly confident that I can accomplish this in my garage with a lift. There are a few special tools listed that seem to be used in addition to a lift table in order to support the unit as it is being removed. The special tools are relatively affordable at 30$/piece from ECS. I have a hydraulic lift table and could rig something up to support the assembly. Alternatively I have made drivetrain cradles for my other cars previously out of some square tubing and threaded rod. How feasible is the removal of the drive unit by a hobbyist/diyer?

My next order of business is to pull the trunk cap and use a stethoscope to locate the source of the noise and to run through the diagnostics procedures in ISTA. Any other suggestions or similar experiences?

Thanks all
Tom
 

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2020 BMW i3S 120Ah BEV
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All I can add here I think is that having seen the build videos on YouTube I can say with confidence that BMW builds all the drivetrain components themselves - the motors are assembled from components and the gearbox/diff are assembled from components right there in the factory. The electronic modules would probably be the only parts they have built by OEMs.

The most likely candidate for failure in general is the gearbox parking brake mechanism but I can't understand why it would start sounding like bad bearings so that may not be your problem. (And the error codes don't point to that either.)
 

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2015 BMW i3 REx 60ah, Solar Orange
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I'd pull the codes on ISTA first as you'd mentioned. Also consider posting this message on BMW i3 forum. In my experience they are more hands-on for this type of DIY overhaul, and certainly a few members state-side that are very knowledgeable. BMW i3 Forum - Index page

Also look at Hubauer Shop in Germany. They list spare parts - which could be useful before you liaise with a dealer, as this will differ from European and US models.

Lastly - it may be possible to pay to access BMW ETKA workshop diagrams. If you do drop the engine, then renew the engine mounts at the same time. In fact I'd have a look just in case they are the culprit. There was a recall for the mounts that could sheer.
 

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Discussion Starter · #4 ·
Thanks for the reply.

I have posted this message on the I3 board as well but so far no replies. The unit being produced isn't great news but it is what it is. My guess as to the failure point would be the differential/transmission case on the output side (where the half shafts connect) which is probably also where the position sensor is hence the codes; but that is just a guess at this point.

I do have to pull the codes using ISTA but it has been freezing cold in Chicago so I have not had the motivation go do more tinkering.

I have been using realoem for the ETK info, I figured the car is old enough that the info there would still be relevant, aside from some superseeded parts and such.

The mounts are definitively on my list(forgot to mention, thanks), but I do not think they are the culprit at the moment, it seems that the engine would be hanging down when that happens.

ISTA diag is next.

PS are there any relevant forums that deal with similar drivetrain, some retrofit folks? I would like to find some detailed images(aside from whats on ebay) of what the drivetrain looks like.

I appreciate the suggestions. Thank you!
 

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... are there any relevant forums that deal with similar drivetrain, some retrofit folks? I would like to find some detailed images(aside from whats on ebay) of what the drivetrain looks like.
This guy has bought a crashed i3 and is videoing the dismantling with a view to building an electric Mini. IIRC, he follows no BMW documentation. This bit has the motor removal:
.
 

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Discussion Starter · #6 ·
Awesome, TY

I did ISTA diagnostics, the following things were of note(below). I ran the test plan for the Inverter and EME internal fault but nothing really came up although I got some decent reading material from it. The position sensor is internal to the assembly and not on the output shaft side, meaning the case would have to be split, which probably means more special tools. Sounds like I will be dropping the drivetrain down.



2228B8 Emergency manager information, EDME: Unable to activate driving
readiness
90637 No Information
222890 Emergency manager information, electrical machine: No internal
signal
90637 unknown Information
22286D Information emergency operation manager: Electrical machine
deactivation
90637 No Information
222869 Information emergency operation manager: Electrical machine
deactivation
90637 unknown Information
222626 EME: Internal fault (active short circuit requested) 90637 No Information
222316 Inverter: Wrong sum current 90637 unknown
22202A Electrical machine, rotor position sensor, signal: Amplitudes too great 90637 No
222029 Electrical machine, rotor position sensor, signal: implausible,
excessive deviation between sine and cosine signal
90637 No
222021 Electrical machine, rotor position sensor, signal: Not plausible 90637 No
222015 Electrical machine, rotor position sensor, signal: Faulty speed 90637 No
222014 Electrical machine, rotor position sensor, signal: Faulty motor position
angle
90637 No
21E96F Driving readiness information: cannot be established after driver's
driving readiness request
90637 No
 

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I'm not crazy, the attack has begun.
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As in on the input shaft to the etrans/diff? I spent some time with a stethoscope but couldn't pin point it from the top. I should be able to run it on the lift.
DON'T RUN IT ANY MORE!!

(Edit; Sorry for that outburst of anxious advice .. it is your car after all!...)


There is a slim chance of some salvage.

It is your pistons rattling, I would presume the big end shells have cracked. Possibly the crank bearings but there is a slight 'ring' to the noise as if the crank is still being held firmly. Crank ends usually come with a dull thudding noise not a ringing noise (the latter being the crank, still held rigidly by the end bearings so it can still 'chime').

You'll have to remove the pistons, the rods will be shot, if you are VERY lucky the crank might still be usable but I'd bet the crank is now damaged too.

Just don't start it again, it is ready to seize.

The above is, obviously, an armchair diagnosis based on a few seconds of youtube video, so you understand there is an element of uncertainty in that diagnosis. Could still be crank bearings rather than rods.
 

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Discussion Starter · #12 · (Edited)
Im relatively familiar(few 800whp engine builds etc) with ICE engines and had my fair share of engine failures and I do not think this is it. Here is why.
  • Runs fine in battery hold and emissions test mode
  • No ICE engine fault codes
  • Idles relatively quiet/smooth (for a 2cyl)
  • Noise happens in EV mode/rolling in neutral, My assumption is the bottom end of the ICE engine is disconnected in EV mode, why would you be spinning it in EV mode?

Honestly I would prefer an ICE failure, My guess is the transfer case/etrans/diff or a bearing internal to the drive motor. The noise is quite different from the typical rod bearing failure (the clicking), the best I can describe it is it resembles a heavily neglected brake rotor/pad combo.

+1 on not driving it, but some diag can only be done while running/driving.

The annoying part is this car doesn't have a center lift point, does it? it's like lifting my mclaren,
 

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I'm not crazy, the attack has begun.
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40,225 Posts
Im relatively familiar(few 800whp engine builds etc) with ICE engines and had my fair share of engine failures and I do not think this is it. Here is why.
  • Runs fine in battery hold and emissions test mode
  • No ICE engine fault codes
  • Idles relatively quiet/smooth (for a 2cyl)
  • Noise happens in EV mode/rolling in neutral, My assumption is the bottom end of the ICE engine is disconnected in EV mode, why would you be spinning it in EV mode?

Honestly I would prefer an ICE failure, My guess is the transfer case/etrans/diff or a bearing internal to the drive motor. The noise is quite different from the typical rod bearing failure (the clicking), the best I can describe it is it resembles a heavily neglected brake rotor/pad combo.

+1 on not driving it, but some diag can only be done while running/driving.

The annoying part is this car doesn't have a center lift point, does it? it's like lifting my mclaren,
It's fair enough that these may well be 'electric machine' noises for which neither of us would be familiar with.

If it is a problem on the electric machine connection interface, as well it might, then it is doing a very good impression of big end bearings.

Good luck with the work.
 

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2020 BMW i3S 120Ah BEV
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It looks like this is the speed sensor, not sure if this is the only one reporting the fault. I assume there is a separate resolver one somewhere inside the EM?

View attachment 155741
This is the cog that the transmission lock mates with to stop the car rolling away, in some archaic attempt to look like a 1950s american cop car when you come to a halt and jump out letting the car fall onto its transmission lock instead of the actual hand brake!
 

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Discussion Starter · #16 ·
I have not logged in here in a while, but here is a quick update. It was the EM that was faulty. The overtemp/position warnings were due to the outer bearing failure. I ended up swapping the EM with a new unit and everything is well.

Some tips if you consider doing this on your own

* Order all the parts ahead of time, specifically look through all the ISTA sections that pertain to this procedure, there is a bunch of torque-to-yield bolts which must be replaced. You also need to purchase the special grease for the input shaft and clean it really well.

* Replace the motor mounts while you're there, the upgraded one requires a bigger m14 bolts and will not fit the old rubber mount, you need the aluminum bracket, rubber mount and the m14 bolt to make it work.

* You don't need all the special jigs, I used a bunch of wood and a 2k lbs rated lift table. Same with the dowels for the transmission to EM connection, just be gentle and it will be fine. Again the shaft needs to be super clean and you need to use the correct amount of the special grease. Shaft diameter is small and so are the splines, improper lubrication will cause premature wear. Align and bolt the motor mounts first and then connect to the front mount(anti roll link).

* You can remove the EM without pulling the transmission, there is one bolt in the way that you can use a 6pt wrench on, this will save you a significant amount of time and extra hardware.

* You need to program the EM calibration data after you're done and complete the bleeding procedures for low temp coolant circuit and REX. The procedure incorrectly says you need to hold the gas pedal depressed for less then 10s, its actually more then 10s, you will hear the electric fan turn on. The coolant overflow tank is baffled, you will not be able to easily hear it run but the level will drop.

* You need a few large E18 / hex sockets for the axle bolts(one time use) so be ready, the sizes are generally not available locally.

* Take pics and sort/label.bag the parts, ISTA pictures are terrible. Having the pictures saved me some time when it came down to routing cables/lines.

Put 5k miles on the car since the repair, car is running great.

The EM should be rebuildable, I just have not bothered trying to find a replacement parts.
 

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I have not logged in here in a while, but here is a quick update. It was the EM that was faulty. The overtemp/position warnings were due to the outer bearing failure. I ended up swapping the EM with a new unit and everything is well.

Some tips if you consider doing this on your own

* Order all the parts ahead of time, specifically look through all the ISTA sections that pertain to this procedure, there is a bunch of torque-to-yield bolts which must be replaced. You also need to purchase the special grease for the input shaft and clean it really well.

* Replace the motor mounts while you're there, the upgraded one requires a bigger m14 bolts and will not fit the old rubber mount, you need the aluminum bracket, rubber mount and the m14 bolt to make it work.

* You don't need all the special jigs, I used a bunch of wood and a 2k lbs rated lift table. Same with the dowels for the transmission to EM connection, just be gentle and it will be fine. Again the shaft needs to be super clean and you need to use the correct amount of the special grease. Shaft diameter is small and so are the splines, improper lubrication will cause premature wear. Align and bolt the motor mounts first and then connect to the front mount(anti roll link).

* You can remove the EM without pulling the transmission, there is one bolt in the way that you can use a 6pt wrench on, this will save you a significant amount of time and extra hardware.

* You need to program the EM calibration data after you're done and complete the bleeding procedures for low temp coolant circuit and REX. The procedure incorrectly says you need to hold the gas pedal depressed for less then 10s, its actually more then 10s, you will hear the electric fan turn on. The coolant overflow tank is baffled, you will not be able to easily hear it run but the level will drop.

* You need a few large E18 / hex sockets for the axle bolts(one time use) so be ready, the sizes are generally not available locally.

* Take pics and sort/label.bag the parts, ISTA pictures are terrible. Having the pictures saved me some time when it came down to routing cables/lines.

Put 5k miles on the car since the repair, car is running great.

The EM should be rebuildable, I just have not bothered trying to find a replacement parts.
Wisely auto did a motor change, secondhand one complete with gearbox it was plug and play, they changed the whole unit because previously it had had a gearbox change by BMW, it at a later date ripped those splines out you were talking about!
If mine was to fail it would be the secondhand route for me as well, plenty of low miles units available cheaply on ebay
 

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Discussion Starter · #19 ·
Wisely auto did a motor change, secondhand one complete with gearbox it was plug and play, they changed the whole unit because previously it had had a gearbox change by BMW, it at a later date ripped those splines out you were talking about!
If mine was to fail it would be the secondhand route for me as well, plenty of low miles units available cheaply on ebay
To clarify, the drive unit was from a salvaged vehicle damaged during shipping (1mile on the clock) at a cost of 600USD. I googled the VIN of the donor car to verify the mileage and spun the shaft by hand before pickup; that's about all you can do without a standalone controller. 2nd hand units are a bit questionable sometimes and I wouldn't want to do this twice. Dealer price was ~3500USD on a new EM, so you figure them odds ;)

I don't know if I agree with the idea of swapping the gearbox as it looked like you would have to unbolt a bunch of other things but to each it's own.

Not sure what went wrong with the swap you had mentioned. The mating surfaces could have gotten damaged either due to the initial failure or at reassembly; or the procedure wasn't followed correctly, BMW is very specific regarding the seals, cleanliness, lubrication and so forth.

While the lift is a prerequisite, everything else was pretty straight forward. If I'm not mistaken the dealer quoted 18k USD for the repair which doesn't leave you a whole lot of options. My GF drove the model X plaid and said she wanted to keep the I3 so here we are :)

-Tomek
 
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