8XL running slow

I am having a problem with an E-Max running way slow. It’s running like the last minute before the batteries die. Previously it was doing about 35 mph for the last 5-6 months. 12020/8XL/12 cells. Temp has been fine on an 18T and strobe slipper. Batteries are fine – I discharged then recharged. I put it together with stock Titans and slipper and it runs fine. The drive train is intact – steel idlers, MIP CVD/Center drives. The 8XL spins smoothly and no apparent damage. My only thought goes to the controller. It did over heat when I was 1st working with the gearing, but has run fine ever since. Any recommendations?

[BrianG]

Stupid question, but has the EPA on the radio been adjusted? Usually, a bad controller has different symptoms like cogging, excessive heat, etc. Also, you might want to try recalibrating your radio to the ESC so it "sees" the full throttle range.

[bdebde]

Probably a bad motor. Are the wires or esc heating up more than usual?

[zeropointbug]

Yeah, either the rotor on the motor is very weak, or it's something else.

If it is the rotor, then the system will be drawing a lot of amps to do nothing, so check your batts for temp, and esc, wires, etc. Like bdebde said.

I did take the Airtronic MX3 redio off and put the original traxxas one on and it performed the same. I did not check the controller or motor temp being it only ran for 1-2 minutes. Is there a way to check the motor to see if it is bad? Is it unlikely to be the controller? I will put it back together, recallibrate the radio and check the EPA. Then I will check the temp. Any further suggestions? Thank you all!

[zeropointbug]

Maybe try doing a free wheel test first... 70% thottle for a couple minutes to see how things go, check temps, then report back. Okay?

Also, do you have any other controllers that you could test it with?

Great advice. No other controller, just the 12020. I will put it together and do the 70% throttle test, take a temp and report back.

I had something similar happen with a 7XL. When I replaced the rotor, it came back to life.

I apologize for my lack of knowledge....when you say replace the rotor, did you have to replace the entire motor or is it something you can repair?

[zeropointbug]

Yes, the rotor is the part that spins in the motor. If you have had it before and it was fine, then maybe you fried the rotor (rpm's kill Feigaos) if you were under geared?

Have you tried running it free wheeled yet?

I have just put the brushless back on and will do the free wheel test before bed. The RPM makes sense. The front center drives broke, so I was driving it 2WD. The temp was nml, but I am pretty sure the RPM were higher than normal. The motor is a Wanderer. I will get back with the test.

Zero, thanks for the input. I did the free well test and the temps were perfect. Turns out it was the EPAs - thanks for the suggestion Brian. I don't understand how they changed. I am pretty happy though, that costs nothing to fix! Thank you all again!