# Unexpected low thrust on Motor 1 & 3 even after cross-swapping FC signal lines – quad tilts forward / then left

**URL:** <https://discuss.px4.io/t/unexpected-low-thrust-on-motor-1-3-even-after-cross-swapping-fc-signal-lines-quad-tilts-forward-then-left/46557>\
**Category:** Uncategorized\
**Created:** [July 18, 2025, 10:53am UTC](https://discuss.px4.io/t/unexpected-low-thrust-on-motor-1-3-even-after-cross-swapping-fc-signal-lines-quad-tilts-forward-then-left/46557 "2025-07-18T10:53:42Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![juliofu0729](https://discuss.px4.io/user_avatar/discuss.px4.io/juliofu0729/32/19927_2.png) [@juliofu0729](https://discuss.px4.io/u/juliofu0729)\
**Post date:** [July 18, 2025, 10:53am UTC](https://discuss.px4.io/t/unexpected-low-thrust-on-motor-1-3-even-after-cross-swapping-fc-signal-lines-quad-tilts-forward-then-left/46557/1 "2025-07-18T10:53:42Z")

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Hi everyone,

I’m troubleshooting a X‑config quad running PX4 v1.14 (stable) on a **Holybro Pixhawk Mini 6C**. The powertrain is **BLHeli‑32 35 A ESCs** and **Emax Eco 2207 2400 KV motors** on 4‑cell Li‑Po. Every log shows that Motor 1 and Motor 3 deliver noticeably less thrust than Motor 2 and Motor 4. With the original wiring the aircraft consistently pitches forward on take‑off.

To verify whether the deficit originates in the ESCs/motors or in the flight‑controller outputs, I swapped the PWM signal lines for M1 and M2 at the flight controller(both a ccw). After that change the vehicle began tipping to the left instead of forward, yet the logs still flag “Motor 1” and “Motor 3” as the weak pair and the aircraft start to tilt left.

this is my flight review before switching the pwm signals :

> **[Flight Review](https://review.px4.io/plot_app?log=d0b09abb-7c88-46d6-a57a-98acdb84ca6e)**

after switching

> **[Flight Review](https://review.px4.io/plot_app?log=5e8615a5-fa03-454d-92c5-4f7c65713789)**

Has anyone seen this problem before? Thanks for helping