# Dyno Mode



## Long Ranger

Has anyone seen or tried out Dyno Mode?










I discovered this in one of Tesla's EPA filings. To enable, hold down the Tesla T for a few seconds, then at the access code prompt, enter "dynotest", holding down the left turn signal when you click OK.

To turn it off, you have to choose Power Off from the Safety and Security tab.

Seems similar to what some have discovered by sending CAN bus commands with bogus data to fault the traction control system. I think the main difference is that Dyno Mode keeps regen enabled (and it doesn't require a CAN interface dongle).

Here's the description from the EPA filing:

_Tesla, Inc. is currently completing the implementation of user interface (UI) features that enable access to our "Dyno Mode" for all users. This feature is required to be enabled to maintain representative driving controls while testing on a chassis dynamometer. Access to Dyno Mode will be introduced at the start of production on October 7th, 2019, and will be deployed to the entire Tesla fleet in version 2019.40 over the month of October 2019.

In order to preserve the proper driving functionality and behavior, Dyno Mode executes the following features: 
‐ Disable Stability Control to ensure no false interaction with the dyno.
‐ Disable Traction Control to ensure no false interaction with the dyno.
‐ Disable Active Drive Line Damping to avoid inducing oscillations in the dyno.
‐ Force the torque split to be as it would be under normal straight‐line driving conditions 
‐ Disable Brake Disk Wipe_

_When the Stability Control and Traction Control systems become faulted, as is the case on a dynamometer where driving is detected but movement is not, regenerative braking is disabled so that unintended braking torque does not lead to loss of traction or control on low friction surfaces. Disabling Stability Control and Traction Control prevents those systems from disrupting regenerative braking behavior, maintaining the most representative driving energy consumption._

_Dyno Mode can be activated by the user, according to the following steps:
1. Vehicle must be in Park.
2. While holding down left (turn signal) stalk, press and hold the Tesla "T" logo at the top of the screen. 
3. Enter the Dyno Mode activation password, "dynotest"._

_Dyno Mode can be deactivated by the user by pressing the "Power Off" button within the Safety & Security tab of the UI._

_We are targeting completion of this Dyno Mode feature for installation in all new production vehicles by October 7th, 2019. Over the month of October, we will be rolling out this feature to our US fleet, enabling all Tesla vehicles to enter Dyno Mode._


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## garsh

@JWardell , you might not need your little contraption after all.


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## Long Ranger

There's also a mention of Coastdown Mode that disables regen, but I'd be concerned about the part where it says it disables the refrigerant system. Could be bad for battery cooling.

_To engage Coastdown Mode:
1. Press and hold Tesla T to bring up Access Code prompt 2. Type "coastdown"
Vehicle Behavior:
UI will send out a binary signal in the message on the right bus. The thermal controller should consume this message and unconditionally close the louver and turn off the refrigerant system.
Display "COASTDOWN" in cluster where we display other mode info like "VALET" and "CHILL" Coastdown Mode will turn OFF after drive cycle is complete._

EDIT: Looks like this mode doesn't disable regen as I had assumed. It only does what's in the description.


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## JWardell

Ten minutes to midnight, and you can be sure I ran straight out to try this!!

It took a few tries because I had to RTFreakingM but I got it!

Well..not as cool as my red button, but then again it would have saved me four weeks of work...

It's not quite the same. First of all there is a ~5Hz pulsation to the motor especially at slower speeds that gets annoying and worrying quick. But also you get a hard punt when you floor it from a stop.
Also, it will reset if you just open the door, stand up, then get back in and press the brake to re-initialize.

Honestly my circuit has been putting it in Rolls Mode (Dyno Mode is another choice), which disables regen but the motor is smooth/normal. I don't remember the dyno mode doing this stuff when I activated it over CAN but I only tried quickly for fear dyno was not meant for use on a car (I'm too used to hooking motors on a steel sled to a crankshaft dyno...who knows how these modes are meant to be used)

I'm going to have to try this while recording everything to see how it compares!
@Long Ranger what other amazing codes do you have for us??

And it's very important to be said:

*WARNING this car is VERY DANGEROUS with traction control disabled! Especially RWD will break free of traction even at slow speeds!*
I'm not joking when I keep calling it Mustang Mode, because it quickly shoots for the sidewalk.
*Please only use off the street well away from other cars and pedestrians!*


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## John

And here's me running to my car typing "devmode," and "developer mode," and ....


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## viperboy

JWardell said:


> ...Honestly my circuit has been putting it in Rolls Mode...


Can you elaborate on this? Is there a way to do this similarly to how Dyno Mode is activated?


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## JWardell

viperboy said:


> Can you elaborate on this? Is there a way to do this similarly to how Dyno Mode is activated?


I'm not sure... Traction control modes we know about are Normal, slip start, rolls mode, Dyno Mode (and track mode which is separate). But I don't remember the Dyno Mode traction control driving the same as this Dyno Mode. I still have to run some experiments when I get time.


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## dburkland

Tried this today, even at 40% SoC it was a lot of fun haha. I really want to baby my winter tires but I might reduce their life a bit tomorrow when I try Dyno Mode again


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## MelindaV

JWardell said:


> WARNING this car is VERY DANGEROUS with traction control disabled! Especially RWD will break free of traction even at slow speeds!


Dual without Traction Control is also pretty squirmy. Some time ago, I had the whole assortment of errors and had a work meeting across town. The screen said something like you are able to drive, but to use caution.. So I went. Including crossing a steel deck bridge. at 25mph, the whole time I was waiting to slide sideways into the guardrail at any moment.


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## michi84

Had some fun in the snow yesterday with dyno mode. You can turn the car around in minimal space with the throttle and keep it in a nice drift. I did not notice any worrying pulsations; the only time when the motor isnt as smooth as normal is at walking speed (like during parking). Maximum power output seems to be limited to pre 5% power increase and no acceleration boost (slighltly above 300 kW combined at about 70% SOC, ~180 KW rear, ~125 KW front), tested on a dry road. I like dyno mode more than the CAN induced one via the app, since regen remains active and with it the feel of the car. 

Also, using a mode which is implemented in the firmware and documented in an EPA document seems less likely to cause warranty problems then sending wrong CAN data to provoke an error which disables stability control. 

I always like to know how a car responds without stability control, to know what characteristics stability control might be hiding. I can use the runway of our small local airfield in the night for such testing (only open in winter on weekends and during daylight because of no runway lighting available, being a flying club member of course helps) with virtually zero risk of hitting anything.


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## garsh

Brooks made two 0-60 runs with dyno mode in a Performance Model 3.

First one, had a little wheel spin, slightly slower 0-60.
Second one, stickier road, managed to get a slightly faster 0-60.


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## JWardell

garsh said:


> Brooks made two 0-60 runs with dyno mode in a Performance Model 3.
> 
> First one, had a little wheel spin, slightly slower 0-60.
> Second one, stickier road, managed to get a slightly faster 0-60.


From Tesla's EPA test, the whole pint of Dyno Mode is to remove nannies that might interfere with a pure acceleration and power test. So by definition it should be exactly the same 0-60 in ideal conditions.
Of course he has a drag racing channel and needs to test it, but you probably don't need to waste ten minutes to find out Tesla didn't lie, they are the same...

...except one of these modes a very dangerous drag race, and the other one can be deadly.


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## EchoCharlie3189

So have we determined if this mode disables TCC and SCC while leaving brake regen on? Or does it turn off brake regen to prevent dyno torque interference?

This sounds like exactly what I was looking for in a track setting to disable the electronic nannies!! If it leaves ABS on then it is a way better solution than disconnecting a wheel speed sensor or even using the party-box mod that MPP is selling. Does anyone know if it turns off above a certain speed or anything like that?


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## JWardell

EchoCharlie3189 said:


> So have we determined if this mode disables TCC and SCC while leaving brake regen on? Or does it turn off brake regen to prevent dyno torque interference?
> 
> This sounds like exactly what I was looking for in a track setting to disable the electronic nannies!! If it leaves ABS on then it is a way better solution than disconnecting a wheel speed sensor or even using the party-box mod that MPP is selling. Does anyone know if it turns off above a certain speed or anything like that?


Regen is still enabled in Dyno Mode. Off in Rolls mode. I'm not sure about ABS. They are both extremely unsafe to use on the road, especially with RWD.


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## michi84

ABS remains on in dyno mode. Testes it yesterday night on our local airfield where one half of the runway was covered with rough ice and frost (really slippery). You can feel the ABS working from the vibrations in the pedal, also, speed is still shown on the display decreasing smoothly (whereas it would go to zero with the wheels locked).

You have to be very careful with the steering, the car always wants to go sideways. 

For fun i tried to keep the car drifting from one side to the other of the icy track (about the width of a country road) by carefully letting the rear wheels spin a little bit, just enough to make the rear end break out and immediately applying countersteering to prevent it spinning out of control. You have to be quick on the steering wheel though and careful with the throttle. 

I wonder how track mode would feel in this situation.


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## EchoCharlie3189

I confirmed the mode works so I am super excited to get on track now. Need to source some track tires/wheels and brake pads and find a weekend!


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## JWardell

You really don't want to use Dyno Mode on a track or any road. It is very unsafe. It's not made for anything but a dyno.

@MountainPass explains why a bit about 2:50 in their video


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## JWardell

Long Ranger said:


> There's also a mention of Coastdown Mode that disables regen, but I'd be concerned about the part where it says it disables the refrigerant system. Could be bad for battery cooling.
> 
> _To engage Coastdown Mode:
> 1. Press and hold Tesla T to bring up Access Code prompt 2. Type "coastdown"
> Vehicle Behavior:
> UI will send out a binary signal in the message on the right bus. The thermal controller should consume this message and unconditionally close the louver and turn off the refrigerant system.
> Display "COASTDOWN" in cluster where we display other mode info like "VALET" and "CHILL" Coastdown Mode will turn OFF after drive cycle is complete._


I activated coast down today. It does appear on the screen, but otherwise nothing seems to change. Regen is unaffected. It may only affect HVAC. Was there any more details to the coastdown note?


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## Long Ranger

JWardell said:


> I activated coast down today. It does appear on the screen, but otherwise nothing seems to change. Regen is unaffected. It may only affect HVAC. Was there any more details to the coastdown note?


No, no more detail, that was the entire description that I quoted. I just assumed it also disabled regen, but it looks like I was wrong about that. I put it in the mode and saw it on the screen, but I didn't test it out.

I figured it must disable regen because coastdown testing is a standard procedure used to characterize the vehicle drag vs. speed for the EPA tests, and there can't be any braking during coastdown. They use it to determine the correct road load force coefficients to program into the dyno. However, the part I missed is that they just put the vehicle in neutral during the coastdown tests, so that's what disables regen for them.


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## JWardell

It made sense to me too because the two other traction control modes that I was activating in hardware were Dyno Mode and rolls mode, and rolls mode disabled regen in addition to traction...assumed they were the same.

I would guess that the expected EPA rating test is to activate coastdown as well as put it in neutral to get the best drag measurement.


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