Has anyone else had this problem with Bosch CX motor?

[Seraye]

Hello!
I have a 2021 Powerfly 5 HT purchased this January with the Trek “emtb lite” firmware upgrade. Around about 150 miles of use,i began experiencing random power “stutters”and the purion display would randomly show the speed jumping up and down (like 2-3mph jumps). This could occur on any mode I was riding in, it didn’t seem isolated to emtb lite. At first this was very random and seldom enough that I thought maybe it was me and not the
Motor, so I ignored it, but then it got worse and finally near 200 miles it became persistent and very annoying and the “stuttering” would be extreme enough to almost throw me if I was standing and climbing. The speed display would continue to jump up and down randomly - and it seems that when this occurs, the motor just lacks “oomph” . So, I took it to the trek dealer, they ran diagnostics, spent lots of time with Bosch techs over the phone, and found multiple error Codes, but couldn’t pinpoint the source of the problem, so they replaced my
Motor for me. Well, 140 miles on the new motor and the problem is starting again, just like last time - random power stutters and the speed jumping up and down... so my question - has this happened to anyone else? Did you take it to a dealer and did it ever get resolved? What did you do?

 

[Atlas79]

I have not seen this problem...yet. I will keep my eyes open for this though. The only insight I have to offer at this point is so obvious, I’m sure it’s already been looked at. BUT, just in case, check the speed sensor. This is an integral component in how Bosch controls, and ultimately limits, the speed. Although, given the e-mtb lite firmware upgrade is relatively recent, I certainly wouldn’t rule that out as a possible culprit.
I would ask the following:
1) What were the error codes?
2) Are the error codes associated with the drive unit directly, or a peripheral part, or wiring?
3] HAS your bike shop or Bosch suggested changing out the speed sensor wiring harness?
This is all I have at this point, but am interested in hearing future developments.
Cheers ?

 

[jerry]

Haven't had speed reading issues, but did have an occasional surge in assistance (though it could be subjective, it's short and seldom). Feels like a short burst of turbo-like power, when in ECO.

 

[Stihldog]

I’ve had a similar issue a couple times (Bosch gen4).
1-metal filings on magnetic sensor.
2-loose wire connections on motor.
3-outdated software/firmware.
Some of these issues showed the 504 error which caused intermittent loss of power. A trip to the LBS was necessary for a reset (and update while I was there).
I regularly clean the magnet sensor with a blast of air (or someone’s toothbrush).

 

[Seraye]

Thank you for the feedback, I considered the speed sensor myself, but it doesn’t happen on my Rail which has double the mileage and grime— one difference being however that the Rail did not have the emtb lite mode until just recently (under 100 miles ago). Today I take the PF in to the LBS for a diagnostic, but I will ask them to roll back the firmware to just the regular tour mode to see if it is a glitch with emtb-lite mode.

 

[Stihldog]

There may be a number of factors for the 504 error or an intermittent lose of power (if I recall).
-a loose magnet on the rotor.
-a loose sensor wire on the motor (2-wire)
-a faulty speed sensor
- metal filings on the rotor magnet
-a broken sensor wire
-a dirty speed sensor
-a reset or update required (LBS)

Some of these are easy to check and remedy on the trail or in your garage with some basic skills. Beyond that…LBS.
I’m not sure if I’d want the firmware rolled-back but it might be worth a try.

 

[mxtyphoon]

I had that problem, but I created it bye pinching the wheel sensor wire with a motor bolt. It’s a 2 wire sensor and can be checked with an ohm meter. It should show some ohms and then pull down to about zero when the magnet passes the sensor. I just repaired the wire myself, but the wires are really small. Good luck
I haven’t had any other problems and just turned over 3,000 miles?

 

[Yoak]

I had it a few times. Metal shavings on the magnet. Every time I had to take the mag Est of the break disk to clean it properly. The shavings stick (as it’s a magnet?) I would try that first. Easiest and cheapest to eliminate

 

[St4nley]

We had this issue on my wife’s powerfly 7 HT that we bought last September, it started after we had the emtb lite update, bosch advice was to roll the firmware back but doing this caused the motor to completely shut down so a new motor was the answer as per your experiance.

we have since sold the powerfly with the remainder of the warranty as we had already purchased a Rail for my wife.

Hope you get this sorted for the second time.

 

[Bobj183]

A few people have mentioned metal filings on the magnet. Do they originate from the disc / pads?

 

[Seraye]

Some good feedback here and I hope more of you out there respond with your experiences. I took the bike back to the shop For a diagnostic , there were no error codes This time and the tech reached out to Bosch for advice regarding the speed sensor. Since that Last trip to the shop, I haven’t noticed the issue at all, so, the jury is out for now, but I will report back if there are any new developments.

 

[Yoak]

A few people have mentioned metal filings on the magnet. Do they originate from the disc / pads?

Yes. Tiny bits from the disk break rotor.

 

[Bobj183]

I've done about 450 miles since Christmas on my 2021 Powerfly 7. I had a short power loss last time out.....just for a few seconds. I'd convinced myself that I was in too high a gear on a hill and had imagined it. I'll start looking out for shards of disc rotor now.

 

[geckonia]

I had an issue with my motor stuttering around 19mph and the display acting erratically… flipped the magnet on the hub from arching up to arching down and that resolved it.