Strange TX / ESC Interaction

[Fallen]

My ol' Bronco used to have the stock brushed set-up, which I swapped out for the Spektrum 2300KV Firma brushless system.

With the stock radio (Spektrum DX3) the brushless system was always very smooth in all driving conditions.

I recently switched the radio to a Spektrum DX5C I picked up used in a local trade. With the DX5C the throttle control feels a bit odd. It's still smooth off the line. But once the truck starts moving forward at a low speed, the throttle seems jumpy. It's like the truck thinks it's moving too fast, tries to slow itself down, and then speeds back up. It continually operates in that cycle so the truck is constantly slowing down and speeding up. It's especially pronounced when the truck is going downhill.

My throttle input stays the same. My drag brake is set to 100%. My RX is the Spektrum SR515. I was running the SR315 previously, and the only difference is that the SR515 has two more channels. I have AVC disabled via the TX, but I don't think the RX is AVC capable anyway.

I've fiddled with adjusting the expo, and throttle response speed with no difference.

Anyone ever seen a problem like this with the DX5C, and fixed it?

 

[rob5059]

I had a similar experience with my DRX4 pro. When I bound a firma 40a, everyone of the profiles was acting up, steering and throttle issues. I had to delete every profile and rebind and calibrate all of the profiles. Everything has been fine since. The firma is in profile 1, thought it might have been a compatibility issue with an older radio. I run an assortment of RX, 210, 410, 415, 515, and the firma.

 

[Fallen]

Thanks. I deleted the profile, re-bound and calibrated. Fortunately I only had one model bound to this radio.

That seems to have sorted it out on initial, front yard testing.

 

[Fallen]

I finally figured out what was causing this:

It's the throttle / torque matching in the ESC; Spektrum's system that automatically increases torque when your tires meet an obstacle. It keeps you from having to input more throttle to keep the same speed over an obstacle.

Now that I have the programming box, I turned that off. No more speeding up and slowing down. My Bronco keeps the same speed unless my finger says otherwise.

It's worth buying the program box for the Spektrum brushless crawler systems. It also allows you to turn the BEC voltage up from 6 volts to 7.4. Your steering servo will thank you. Unless it can only handle 6V. Then your servo won't thank you, because it will be dead.

 

[cooper_xl]

it is strange to act that way. Atleast on the Fusion, the FOC is smooth.

 

[cooper_xl]

It also allows you to turn the BEC voltage up from 6 volts to 7.4. Your steering servo will thank you. Unless it can only handle 6V. Then your servo won't thank you, because it will be dead.

. good one

 

[Fallen]

it is strange to act that way. Atleast on the Fusion, the FOC is smooth.

I was surprised to see it behave negatively, especially combined with a Spektrum RX / TX. I did like that torque matching feature when an obstacle was encountered.

 

[cooper_xl]

I've seen the Fusion SE not getting along with TRX-4 stock radio/receiver so anythings possible. My always worked flawlessy