Max10 SCT and Max8 stuttering on full throttle

[Hector_Fisher]

I'm a bit at my whits end on this. I've tried a miriad of changes to try and isolate the issue with no success. Max8 and max10 SCT are aliexpress RTRs bought about 4 months apart. Both are stuttering on heavy launch like this:

Trucks as follows:
-MT410 stock with max8 and 4074 2050kv spektrum motor, 15t pinion. Flysky gt5 rx/tx running 6s.
-Big rock with minors mods (metal diff, rpm arms) max10 SCT and 4068 2650kv surpass motor, 18t pinion. Stock rx/tx running 4s.

I've swapped batteries, tried running these batteries in a different truck (which ran fine), changed punch up to max, the gt5 drives my SCT410.3 just fine (running a spektrum 130a esc). Tried the big rock on 3s (which seemed to help a little. At first I thought it was radio interference, but my SCT410.3 drives fine on the same gt5, my kaiju drives fine. The other two guys driving today had no issues (one with a gt5 as well). The only thing in common between these two trucks is the hobbywing brand ESC.

I can get on full throttle with a slow, long press. But if I jam the throttle down, it's almost like both ESCs start cutting out. It can't be that they are pulling too much power...?? Your thoughts and advice are really appreciated.

 

[razorrc]

Check the capacitors aren’t blown/bulging.

 

[Hector_Fisher]

Check the capacitors aren’t blown/bulging.

Definitely not my area of expertise. From what I can tell, the capacitors are intact and free of damage.

 

[razorrc]

Does it hit full throttle instantly with the wheels off the ground? If so, then maybe overgeared. If not, then probably electrical issue.

 

[Garcbomber]

On my max8v3 I had this issue with too much gear/tire that was able to be cleaned up with more punch. It’s a balancing act, also I’m presuming you already recalibrated the WFO tiggers on the transmitter to the ESC/motor.

 

[Hector_Fisher]

Does it hit full throttle instantly with the wheels off the ground? If so, then maybe overgeared. If not, then probably electrical issue.

Wouldn't that be the other way around? If it takes a while for an unloaded truck to spin up, then it's too overgeared? The big rock is geared for stock speeds, the only difference is that i'm now running it on 4s. For the MT410, i'm starting to suspect an electrical issue as well. i don't remember having this issue right when i first installed the max8.

On my max8v3 I had this issue with too much gear/tire that was able to be cleaned up with more punch. It’s a balancing act, also I’m presuming you already recalibrated the WFO tiggers on the transmitter to the ESC/motor.

I'll attempt recalibrating them again Maybe second times the charm. I did up to max punch (5) on both ESCs to see if that helped. No dice.

The interesting thing is, I can hit full throttle and get full power, but only when i ramp up very slowly. If I wanted to punch it to get a backflip or something, no dice as well.

Could this be a motor issue? I had to resolder the big rock's surpass motor bullet since the factory did crappy solders. Perhaps I did a poor job or messed something up? I'm wondering if it's a bad connection (on both trucks) where normal amerpage is fine, but one phase has a poor connection, so under high amp draw (like pinning the throttle), it saturates the connection?

 

[Garcbomber]

I watched your video, different issue. Seems like a wiring load problem, it doesn’t stutter with 1/2-3/4 trigger launch?

 

[KnowAir]

I'm wondering if you have 2 receivers going bad? Seems unlikely though..but maybe?
Also, definitely recalibrate the throttle range on both.
I'd try throttle calibration first, then swap out a known good receiver into one of the troubled rigs..
On a side note, check radio settings between models and make sure something didn't get changed by accident..

 

[Hector_Fisher]

I watched your video, different issue. Seems like a wiring load problem, it doesn’t stutter with 1/2-3/4 trigger launch?

No it still does. Now I'm remembering i tried like 1/4 throttle "putting around" as well. Even holding the trigger steady, it still seemed to be stuttering. Almost like an engine misfire. But it wasn't happening all the time. Which made me think it was some radio issue at first. But same controller worked on my SCT410 with the spektrum ESC with no issues, and my kaiju was running fine (stock rx/tx) and two buddies were running their trucks with no problems.

I'm wondering if you have 2 receivers going bad? Seems unlikely though..but maybe?
Also, definitely recalibrate the throttle range on both.
I'd try throttle calibration first, then swap out a known good receiver into one of the troubled rigs..
On a side note, check radio settings between models and make sure something didn't get changed by accident..

By this point i'm guessing either two random receivers going bad or two random ESCs going bad.

I'll recalibrate again. I can swap in my kraton rx and see if that does the trick as well. Cross my fingers that one of those does the trick.

 

[razorrc]

Wouldn't that be the other way around? If it takes a while for an unloaded truck to spin up, then it's too overgeared? The big rock is geared for stock speeds, the only difference is that i'm now running it on 4s. For the MT410, i'm starting to suspect an electrical issue as well. i don't remember having this issue right when i first installed the max8.

No, if it's unloaded then you should be able to hit full throttle super fast since there is nothing to slow it down.

By the way, I watched your video, it's not just the tires skipping off the ground or the slipper slipping? It actually doesn't seem like it's cutting out, but it's hard to tell what you're doing with the trigger, so I can't tell what the truck is doing vs. what you're doing with your trigger. Did you try it on the road? It'll be more obvious what it's doing on a smooth straight surface.

 

[Hector_Fisher]

No, if it's unloaded then you should be able to hit full throttle super fast since there is nothing to slow it down.

By the way, I watched your video, it's not just the tires skipping off the ground or the slipper slipping? It actually doesn't seem like it's cutting out, but it's hard to tell what you're doing with the trigger, so I can't tell what the truck is doing vs. what you're doing with your trigger. Did you try it on the road? It'll be more obvious what it's doing on a smooth straight surface.

Thanks for the feedback. Agree, i could have made the video more clear. I'll try to be more clear in what i'm trying to show for future videos, maybe add some narration.

For clarity, the first pull at 0:00 and the pull at 0:13 are absolutely 100% full throttle--pinned. The area is all entirely loose dirt, so it should just throw rooster tails. My frame of reference is when i had the blx100 installed and running 3s (same gearing), if I pinned the throttle, the truck would just throw dirt, no skipping. This is definitely a "stutter" of power. Big rock is geared for stock speed, but I'll try an unloaded spin to validate that nothing seems wrong and grab a video if I notice anything peculiar.

MT410 with the max8 is acting the exact same way, so i didn't suspect any slipper issues with the big rock. I initially noticed the issue when I was going to try and hit backflips off jumps (both trucks), a high grip situation on the up slope of the jump.

I'll give it a shot on the asphalt and check for anything unexpected.

 

[Hector_Fisher]

Update: Max8 just went up in smoke.

So I had swapped out the servo on the mt410 just to see if the servo was causing the issue for the max8. Everything seemed to be running fine during my bashing. Was still getting the same sputtering. Then the mt410 stopped dead in the air, and it tumbled to the ground. I ran over and the esc was smoking. Luckily I was able to unplug everything quickly. Guess that explains why the max8 was acting weird. PTSD from my spektrum 150a kicking in strong...

Didn't think that max8's failed like that very much???

The max10 has been acting the same way the max8 was. I got another video of the sputtering on the max10. Throttle was held down about 1/4 to 1/3 throttle constant, and the sputtering is pretty evident. Now that I know the end result might be an esc going up in smoke, I'm hesitant to use even the max10 now.

I might be done with aliexpress hobbywing ESCs...

 

[razorrc]

All my sensorless ESCs stutter at 1/4 throttle.