I have an LRP Sphere TC Spec with some history (I had it and it worked but the set up button went on it so I sent it to Associated and they fixed the setup button, the put a new cap and new rx wire on it and tested it saying it worked) I bought a used 21.5 Trinity High Velocity motor and that's the only sensored motor I have so I can't test the esc with a different motor.

When I advance the throttle, the motor squeaks a little, shutters, vibrates, and sometimes spins a little. It seems like it's not getting enough juice. IF I spin the wheels (like a kick start LOL) the motor runs and works as long as I don't drop the throttle to zero.

Any ideas what this could be, is it the motor or the esc? Any way I can test the esc with a multimeter?

Thanks in advance.

This is a sensor communication issue. either your sensor wire or your motor's sensor is damaged. These symptoms you describe are because the ESC is not able to detect what position the rotor is in, so the motor "Cogs". By spinning the wheels or giving them a bump you initiate the rotation needed to defeat the lack of position information.

Start by trying a new sensor wire, if that doesn't remedy it, the motor sensor is most likely the problem.

Thanks Banshee. I do believe it's the sensor plug on the motor now that you mention that. I tested it later this morning and noticed the speed control would send the signal that it didn't have connection to the motor. And yes, I believe it's the motor.

Now I believe this motor can run sensorless, if the sensor plug goes bad, then the motor could still run on a sensorless esc, correct?

Also if the same systems were happening with a sensorless esc, what could be the cause of that?

I'm not an expert on this by any means, but my understanding is that a motor with hall sensors has a slightly different set-up internally than a sensorless motor. I think it is minor, but significant enough that you experience the same symptoms on a sensorless ESC. I don't know the specifics, like if it is just internal timing or more complex than that, but that is what I remember reading somewhere on RC-Tech. Sorry, I don't have the thread for you.

Sensored motors are generally wound in a different fashion that causes them to run poorly without sensors. Some faster winds(IE:lower turns), will run decent, but anything over 13.5 will almost always run very poor on a sensorless controller. There are exceptions, and I am not familiar with your motor, so dont take my word for it. If the manufacturer says it can run sensorless, and it performs the same way on a sensorless controller, then I would suspect it is a bad phase in the motor. The symptoms you described could be attributed to many possibilities, bad sensors, bad phase in the motor, blown MOSFET in the ESC, or a poor/failing connection between the ESC and motor. Without expensive testing equipment I dont think there is any way to test brushless components other than known good components.