Yamaha PW-ST Pedal Response

[Getitright]

I have a Haibike Trekking 6 i630, with Yamaha PW-ST motor. I find the motor response at low pedal pressure somewhat erratic. When pedaling lightly, I notice two things:

• The assistance ramps on and off with slight variations in pedal pressure. This can be provoked by changing into a lower gear and spinning faster. It can be prevented by changing into a higher gear and pushing harder on the pedals. This is audible as well as felt.
• With low pedal pressures, the assistance "stutters" over slightly uneven surfaces (as the pedal pressure fluctuates accordingly). imagine saying "eeerrrr" or "ahhhh" while riding over a series small bumps, and your voice sounds jerky - the motor feels and sounds the same.

Pushing harder on the pedals, everything seems fine. But I like to spin and use less pedal pressure, so it happens quite a lot. My thoughts have always been that (perhaps) either the resolution of the torque sensor is poor at low pedal pressures and/or the motor algorithms are too responsive to small changes in light pedal pressures. Also, I have heard of a batch of motors that were programmed incorrectly - could mine be one? It's a 2022 model, purchased in early January 2023.

NB No error codes at any time.

Thoughts, anyone?

PS In case anyone is interested:
Battery range is excellent - typically 160 miles in power level 1 (+ECO), after a full charge (630 Whrs). After 31 miles of fairly hilly going the other day, I had lost exactly 31 miles range - it was down from 162 miles to 121 miles. Admittedly I used the gears a lot. I used level 1 (+ECO) on the level and for gentle hills, and level 2 (ECO) on steeper hills and for strong headwinds near the coast. A power level higher and I would have been doing pretty good speed and still had loads of range.

 

[Stokes9315]

I would love to know if you ever solved this issue . I have the same thing going on. I'm guessing it may be bearing slippage ? Any ideas on how to rectify the issue please

 

[Stokes9315]

On further diagnostic checks my tourque sensor voltage is high at 0.5v and the range should be 0.1-0.2 , was this the issue with your bike ? Did you have a tourque sensor replaced ?