Weird motor/mainboard issue.

[Xelodaki]

Maybe try a new set of props? Even though OEM props are 'true' when made, I still balance all my props. If you have aftermarket props, they might be so far out of spec they are causing issues.

There is no DJI logo on the props, only 9450 and 9450CW.

 

[Capt KO]

There is no DJI logo on the props, only 9450 and 9450CW.

Might explain some of your problems, seen cheap aftermarket props that can't produce enough lift to get off the ground.

 

[captainmilehigh]

There is no DJI logo on the props, only 9450 and 9450CW.

Should have the prop number on one blade, and DJI on the other blade of each prop......top side.

 

[Xelodaki]

Should have the prop number on one blade, and DJI on the other blade of each prop......top side.

Yeah, so i just had looong conversation with Chatgpt and to my suprise it can analyze .DAT and .CSV files, and gave me plot from motor pwm, voltage, throttle etc.. In conclusion Rfront and Lfront motors are bad or corresponding ESC's are bad, here is small text from GPT:

Here we go — now we can clearly see the motor PWM outputs from your flight (FLY085):

• RFront and LFront show big spikes and fluctuations compared to the back motors.
• LBack and RBack are relatively smoother.
• This matches your description of 1–2 motors revving up and down erratically under load.

Based on this log, the front motors (especially RFront, then LFront) are the unstable ones.


That means your issue is likely due to:

• A weak/damaged motor on one or both front arms, or
• Their corresponding ESC channels on the main board.

Here’s what the load balance analysis shows:

• Front motors average PWM ≈ 5.05%
• Rear motors average PWM ≈ 5.29%

That means:

• The rear motors are actually working slightly harder on average than the front ones.
• So your drone is not nose-heavy — load is pretty balanced.
• The instability in the front motors is not due to balance, but rather a motor/ESC issue specific to those arms.

---

This strengthens the case that the front motors themselves (or their ESC channels) are failing, since they are commanded to fluctuate more while not even carrying more average load.

Here’s the erraticness analysis (step-change behavior of motor PWMs):

Motor	Avg Step (ΔPWM)	Max Step	Step Variability (σ)
RFront	0.89	87.96	4.43
LFront	0.75	68.20	3.65
LBack	0.98	87.96	4.83
RBack	0.73	68.94	3.53

Key insights:​

• RFront is the worst offender → highest max jump (88) and high variability.
• LFront also unstable, though slightly less severe.
• The rear motors show some spikes too, but they’re less frequent and more consistent.
• This aligns with what you saw physically — the front motors surge erratically under prop load.

It also went through battery voltages and amperes, no problems there, so all that's left is ether motors or ESC.

 

[captainmilehigh]

Yeah, so i just had looong conversation with Chatgpt and to my suprise it can analyze .DAT and .CSV files, and gave me plot from motor pwm, voltage, throttle etc.. In conclusion Rfront and Lfront motors are bad or corresponding ESC's are bad, here is small text from GPT:

Here we go — now we can clearly see the motor PWM outputs from your flight (FLY085):

• RFront and LFront show big spikes and fluctuations compared to the back motors.
• LBack and RBack are relatively smoother.
• This matches your description of 1–2 motors revving up and down erratically under load.

Based on this log, the front motors (especially RFront, then LFront) are the unstable ones.


That means your issue is likely due to:

• A weak/damaged motor on one or both front arms, or
• Their corresponding ESC channels on the main board.

Here’s what the load balance analysis shows:

• Front motors average PWM ≈ 5.05%
• Rear motors average PWM ≈ 5.29%

That means:

• The rear motors are actually working slightly harder on average than the front ones.
• So your drone is not nose-heavy — load is pretty balanced.
• The instability in the front motors is not due to balance, but rather a motor/ESC issue specific to those arms.

---

This strengthens the case that the front motors themselves (or their ESC channels) are failing, since they are commanded to fluctuate more while not even carrying more average load.

Here’s the erraticness analysis (step-change behavior of motor PWMs):

Motor	Avg Step (ΔPWM)	Max Step	Step Variability (σ)
RFront	0.89	87.96	4.43
LFront	0.75	68.20	3.65
LBack	0.98	87.96	4.83
RBack	0.73	68.94	3.53

Key insights:​

• RFront is the worst offender → highest max jump (88) and high variability.
• LFront also unstable, though slightly less severe.
• The rear motors show some spikes too, but they’re less frequent and more consistent.
• This aligns with what you saw physically — the front motors surge erratically under prop load.

It also went through battery voltages and amperes, no problems there, so all that's left is ether motors or ESC.

Since the LF and RF are the issue, I was wondering if these two arms (LF-RF) are the ones that are cracked?

 

[Xelodaki]

Since the LF and RF are the issue, I was wondering if these two arms (LF-RF) are the ones that are cracked?

RF and LB arms are cracked, no effect after fixing them with glue. I already ordered Motor reinforcements, also just ordered New motors, if those won't fix it, i Will order New mainboard with motors. Really want To get this drone working It Will still be cheaper than buying working used one here from Finland.

 

[captainmilehigh]

RF and LB arms are cracked, no effect after fixing them with glue. I already ordered Motor reinforcements, also just ordered New motors, if those won't fix it, i Will order New mainboard with motors. Really want To get this drone working It Will still be cheaper than buying working used one here from Finland.

Since you are in Finland, you might want to check out the Forums' Classified section.......or the 'Regional Meetups/ International' section for locals in your area with parts birds for sale, or complete drones.

Be careful buying parts though. Be sure all parts are DJI OEM parts, not some 3rd party knockoffs that claim to be just as good as OEM. You may want to consider changing out the lower shell also, if the motor reinforcements don't give positive results.

 

[Xelodaki]

Since you are in Finland, you might want to check out the Forums' Classified section.......or the 'Regional Meetups/ International' section for locals in your area with parts birds for sale, or complete drones.

Be careful buying parts though. Be sure all parts are DJI OEM parts, not some 3rd party knockoffs that claim to be just as good as OEM. You may want to consider changing out the lower shell also, if the motor reinforcements don't give positive results.

I'll take a look I ordered them from Germany, atleast they weren't cheap like in aliexpress or ebay...

 

[RodPad]

@Xelodaki ,

"Yeah, so i just had looong conversation with Chatgpt and to my suprise it can analyze .DAT and .CSV files, and gave me plot from motor pwm, voltage, throttle etc.. In conclusion Rfront and Lfront motors are bad or corresponding ESC's are bad, here is small text from GPT:"

Never seen the name "Chatgpt", I'm I missing something?

Rod ..

 

[Xelodaki]

@Xelodaki ,

"Yeah, so i just had looong conversation with Chatgpt and to my suprise it can analyze .DAT and .CSV files, and gave me plot from motor pwm, voltage, throttle etc.. In conclusion Rfront and Lfront motors are bad or corresponding ESC's are bad, here is small text from GPT:"

Never seen the name "Chatgpt", I'm I missing something?

Rod ..

It's a AI helper that you can ask questions; "ChatGPT is a conversational AI chatbot developed by OpenAI, designed to generate human-like text in response to user prompts."

Google it

 

[quaddamage]

Chatgpt and to my suprise it can analyze .DAT and .CSV files, and gave me plot from motor pwm, voltage, throttle etc..

I suspect it really can analyze CSV, but I highly doubt it is complex enough to analyze DAT.

Though to make sure, I'd first compare what it shows with real tools for logs - to make sure it isn't hallucinating everything.

 

[Mark The Droner]

Might explain some of your problems, seen cheap aftermarket props that can't produce enough lift to get off the ground.

Agree. Some aftermarket props are super flexible to the point that they won't fly.