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Initial TACC Speed crazy fast

Warning: New owner and admittedly have not read the manual question...I did search and cant find any threads on this:

When engaging TACC for 1st time each day (pulling stalk towards the driver once), the max speed initially sets to 85 mph. This gets screechy when the legal limit is only 45 and this car takes off like a rocket. I know I can use up/down to engage at current speed, but the pull-back motion is a habit to engage system. Is there a way to set default speed?? Thanks.
 

brkaus

Well-Known Member
Jul 8, 2014
8,540
7,170
Austin, TX
Warning: New owner and admittedly have not read the manual question...I did search and cant find any threads on this:

When engaging TACC for 1st time each day (pulling stalk towards the driver once), the max speed initially sets to 85 mph. This gets screechy when the legal limit is only 45 and this car takes off like a rocket. I know I can use up/down to engage at current speed, but the pull-back motion is a habit to engage system. Is there a way to set default speed?? Thanks.

How fast are you going when you engage?

What is the speed limit sign saying on the dash at the time?

It sets to the offset defined in controls > settings > driver assistance > speed assist
 

chillaban

Active Member
May 5, 2016
3,723
6,599
Bay Area
Yes, this (accidentally plucking the stalk) is often the cause of Tesla SUA (Sudden Unintended Acceleration), and the Tesla black box might even misleadingly record it as your foot on the gas pedal.

What are these unsubstantiated theories? You can't even engage TACC under 18mph (e.g. in a parking lot) without a lead car, and it will not rocket forward in the presence of a lead car that's stopped in a parking lot either.

TACC acceleration is still ramped and rarely goes beyond 150kW after a second, and if you cannot tap the brake pedal to react to TACC acceleration in time before something goes wrong, there's something wrong with your driving...
 
What are these unsubstantiated theories? You can't even engage TACC under 18mph (e.g. in a parking lot) without a lead car, and it will not rocket forward in the presence of a lead car that's stopped in a parking lot either.

TACC acceleration is still ramped and rarely goes beyond 150kW after a second, and if you cannot tap the brake pedal to react to TACC acceleration in time before something goes wrong, there's something wrong with your driving...
I'm glad you said it. ;-) And I am always puzzled when someone says unintended TACC activation will "launch" the car suddenly. :)
 
Two Examples this week:
1) On the highway 65mph speed limit going 65, and TACC engages at 80max.
2) On 2-way road 45mph speed limit going 45, and TACC engages at 80max.

I thought this is just for the warning "settings > driver assistance > Offset from speed limit " was just for the speeding warnings. Which do currently chime at +15mph on my car. Does this +15 also influence the default TACC max?

Driver-Assistance-Settings-1024x718.jpg
 

brkaus

Well-Known Member
Jul 8, 2014
8,540
7,170
Austin, TX
Two Examples this week:
1) On the highway 65mph speed limit going 65, and TACC engages at 80max.
2) On 2-way road 45mph speed limit going 45, and TACC engages at 80max.

I thought this is just for the warning "settings > driver assistance > Offset from speed limit " was just for the speeding warnings. Which do currently chime at +15mph on my car. Does this +15 also influence the default TACC max?

View attachment 285260
Yes, the offset does also define the TACC default. Based on experiments. I have my offset set at 5mph absolute. Every time I start the TACC (above 18 mph), it goes to the speed indicated by the speed limit sign on the dash + 5 mph.
 
Last edited:

ecarfan

Well-Known Member
Moderator
I thought this is just for the warning "settings > driver assistance > Offset from speed limit " was just for the speeding warnings. Which do currently chime at +15mph on my car. Does this +15 also influence the default TACC max?
Yes.

At some point you must have set your “offset from speed limit” at +15. The car didn’t do that itself. So that explains the surge of acceleration when the car is doing what you have instructed it to do.

That is a huge offset. I have never driven in Virginia, but in California I would get ticketed for going 15 over any speed limit. I set my offset at +7 and I only use TACC on freeways and open highways.
 
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I just didnt understand that the offset setting was for the warning chime AND TACC initial max speed. Ill set it back to zero and go back to using WAZE for speeding warnings.

In Virginia, they will automatically put you in jail 1 day for every mph over +20 and charge with a class 1 misdemeanor (same as DUI, animal cruelty, sexual battery, and aiming a firearm at someone). 25 years of driving in NY no speeding tickets for me, but 3 tickets in three years in VA. I have had a couple friends locked up for speeding - Ticket for 25 over = 5 days in jail.. Story on Jalopnik
 
I just didnt understand that the offset setting was for the warning chime AND TACC initial max speed. Ill set it back to zero and go back to using WAZE for speeding warnings.

In Virginia, they will automatically put you in jail 1 day for every mph over +20 and charge with a class 1 misdemeanor (same as DUI, animal cruelty, sexual battery, and aiming a firearm at someone). 25 years of driving in NY no speeding tickets for me, but 3 tickets in three years in VA. I have had a couple friends locked up for speeding - Ticket for 25 over = 5 days in jail.. Story on Jalopnik
Sounds like Virginia won't be getting any of my vacation money. I'll stay away from there.

Some time ago, I had the same thought about the offset. I thought it was just for the ding warning of going over the speed limit. After I realized it was also tied to the TACC, I set it back low and turn off the warning. It would be nice to have separate settings for those two things.
 
@morrisdl Don't feel too bad. I set my "offset" to +10. Before Tesla limiting speed on surface streets, a friend asked if the X could handle the curves (25mph warning). I said sure and pressed into "autopilot". The X accelerated immediately and tried to get to the normal 40mph speed plus the offset -- zoom to 50mph into the first 25mph curve. Can anyone say DEPENDS!!
 

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