R1S Mystery Diagnostic Adventure

[riivian]

I have 2023 R1S Adventure with Quad Motor and 21" wheels/tires (everything is stock on this vehicle) that has a very mysterious situation and it's been in for service 5x for this issue and going on 6th this coming week. Rivian service techs and Customer Service have been great to work with and to get me in quickly. The issue is that the techs are completely stumped on what the issue is. So let's see if anyone can figure this one out.

The vehicle starts to vibrate above 60mph after I put it in Highway Assist after I go through turn when it's auto steering. The vibration is a mid/low level frequency shuddering vibration that can be heard and felt through the entire vehicle. You can see the steering wheel shakes slightly too but the vehicle shakes just the same. When I disengage Highway Assist the problem goes away. Then if I put it in just Cruise Control it will immediately whether I am in a turn or straight. It seems the turn above 60mph with Highway Assist is the trigger.

The following has been done while in service:

Replaced Steering Column(due to vertical adjustment failing)
Replaced Steering Wheel
New wheels
New Tires(3 sets total and even hand picked the ones from their Pirelli stock with the lowest Roadforce variance)
Roadforce balances 3-4 times
Alignment
New half shafts

Truck drives perfect other than this scenario, but Highway Assist and Cruise Control are unbearable. They had a special tech out there even that travels around for difficult issues and he was not able to figure it out either. Anyone know or experience this before?

Thanks for attempting to solve this mystery!!!

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[Glembi2]

Wow. That sounds like an intermittent wheel speed sensor issue where the highway assist / cruise control is somehow relying on data from the wheel speed sensors. Going straight is not an issue. But turning at speed seems to throw off what the vehicle thinks is happening (one pair of wheels needing to turn more than the other pair).

 

[jjswan33]

I would think if Rivian can't fix it this time it might be time to ask them to buy it back.

 

[riivian]

That’s is a really good thought and I wonder if that is the case why would it continue to do it when I go straight even when I reengage Cruise Control or Highway Assist?

 

[riivian]

I would think if Rivian can't fix it this time it might be time to ask them to buy it back.

Yes it’s an option , but want to avoid as I have an R1T also and both of these vehicles have all the bugs worked out of then after several service visits. I feel like even a replacement will likely have the same. Since this is a quad and there is no new quad out yet, then I want to keep this one. It does meet the buy back lemon law requirements but I don’t want to go through this process if at all possible. I would need to rewrap the vehicle etc too.
Let’s see if we can nail this “one last issue”

 

[jjswan33]

Yes it’s an option , but want to avoid as I have an R1T also and both of these vehicles have all the bugs worked out of then after several service visits. I feel like even a replacement will likely have the same. Since this is a quad and there is no new quad out yet, then I want to keep this one. It does meet the buy back lemon law requirements but I don’t want to go through this process if at all possible. I would need to rewrap the vehicle etc too.
Let’s see if we can nail this “one last issue”

I can respect that, good for me as an investor

6 repair attempts is a lot though... hopefully they sort it out this time. Wishing them luck...

 

[Billyt1963]

Is the vibration like it is lane correcting or is it something else?

 

[riivian]

I am not attempting to change lanes or recentering. It starts doing it while I am in one lane after a moderate sized highway turn.

 

[Billyt1963]

Understood, my R1T doesn’t care for the road I drive on the most and often jerks to get me back in the lane. I was wondering if for some reason the turn is confusing the computer/camera and it is jerking back and forth to get you in the middle of the lane.

Since You have had so many physical items replaced, I was thinking it might be software related.

 

[Kunzene]

No system fault or error messages when this occurs?

 

[riivian]

No system fault or error messages when this occurs?

Good question and I should have stated no errors either.

 

[riivian]

Understood, my R1T doesn’t care for the road I drive on the most and often jerks to get me back in the lane. I was wondering if for some reason the turn is confusing the computer/camera and it is jerking back and forth to get you in the middle of the lane.

Since You have had so many physical items replaced, I was thinking it might be software related.

I have thought software too and all of this is good input. I have racked my brain and so have the techs going into round 6. I think as a collective here maybe we can figure this out on some level. It’s the last issue and after that this R1S is golden. It is as if there is an imbalance on one of the 4 quadrants of the vehicle. I am trying to think what engages and turns “On” in the moments but won’t turn “Off”

 

[Kunzene]

I am not sure if what I experienced was similar to your issue, but last year my R1T had progressive issues with driver assist that generated various system faults. I occasionally experienced a shuddering that I would compare to jerky acceleration and deceleration like a ICE vehicle stalling out. My ASM module was faulty and was replaced along with the spoiler.

 

[riivian]

I do wish I had a system fault as that would help. Which makes me think what items are not attached to a sensor in those moments that it can’t read? I’ve thought maybe a hung up caliper if it decided to slow down for the turn or maybe suspension related. The techs and I were thinking it was wheel balancing since the moment the Cruise Control goes off, the speed varies. I have tried driving at the same speed with my foot and still can’t get it to do it. I have thoughts on drive train being the issue potentially too.

The wheel sensor is an interesting suggestion though but would it cause errors elsewhere?

 

[Glembi2]

The wheel sensor is an interesting suggestion though but would it cause errors elsewhere?

TL: DR Option 3 below could be the fastest way to figure out what is happening

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The key point for me is not what happens but when it happens. Those long sweeping curves that gradually trace different length paths has to be it.

You might try these and see what happens:

1. Find a curve that starts the truck shimmying on all purpose. Go back over that section of road again but this time on conserve. That could isolate the issue to be just the rear wheels if the problem does not happen in conserve mode.

2. Try turning on highway assist only after entering the corner. If the truck is fine in the corner but then shimmies on the next straight, my money is on a hardware component making the software think the wheels are turning at different speeds when they are not.

3. The tech should be able to monitor (either via the RIDE menu or via an OBDC monitor) what the wheels are doing when the shimmying starts. Specifically, check how much torque is being applied to each wheel when the truck is shimmying (check the numbers behind the blue bars of each wheel in the settings display). I’m guessing one will be a few percent higher or lower than the rest.

Before TPMS, there was another way to notify drivers that one wheel was underinflated. Count the wheel rotations over a long distance. If one rotated more and all other things being equal, there was a good chance that wheel was under inflated. Rivian could be doing something similar by concluding a wheel was under inflated. But I doubt it.

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