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-   -   Problem with torque sensor? (https://www.ft86club.com/forums/showthread.php?t=123920)

covance 12-08-2017 02:29 PM
Problem with torque sensor?
 
Hello all!

2015 BRZ with 25,000 miles on it. I had my rear driver side tire blow out recently and had to get a new quickly, so it unfortunately it does not match the passenger rear tire from a thread pattern and brand perspective. However, size and approximate wear do match (not many miles on the car).

I took my car in to get an alignment. The alignment was done properly, but the mechanic said he believes there is a problem with my torque sensor. When you step on the gas (for example at highway speeds) there is a significant pull to the left, and when you let off the gas the car goes back to the right. This phenomena does not happen at lower speeds on city streets. The mechanic said this excessive steering torque should be automatically corrected by the electric steering but it is not.

There are no error lights on the dashboard.

I am thinking of switching the front and rear driver side tires to see if the problem goes away (so that the two rear tires will be matched).

I told my mechanic this and he said he already tried this and it did not work. He thinks it is definitely a torque sensor/software issue and that I need to take it to Subaru before my warranty is up (that is a whole other issue. I have not hit 36k miles but have passed 3 years. I called one dealer who said ECU is not covered by the 5 year powertrain warranty but based on some Googling I think he was BSing me).

Any thoughts on this issue? Am I going about this the right way?

Thanks everyone for your thoughts. I wasn't sure what "technical issue" subforum this belongs in so I am posting in the general section for now.

Tcoat 12-08-2017 02:42 PM
Quote:
Originally Posted by covance (Post 3014052)
Hello all!

2015 BRZ with 25,000 miles on it. I had my rear driver side tire blow out recently and had to get a new quickly, so it unfortunately it does not match the passenger rear tire from a thread pattern and brand perspective. However, size and approximate wear do match (not many miles on the car).

I took my car in to get an alignment. The alignment was done properly, but the mechanic said he believes there is a problem with my torque sensor. When you step on the gas (for example at highway speeds) there is a significant pull to the left, and when you let off the gas the car goes back to the right. This phenomena does not happen at lower speeds on city streets. The mechanic said this excessive steering torque should be automatically corrected by the electric steering but it is not.

There are no error lights on the dashboard.

I am thinking of switching the front and rear driver side tires to see if the problem goes away (so that the two rear tires will be matched).

I told my mechanic this and he said he already tried this and it did not work. He thinks it is definitely a torque sensor/software issue and that I need to take it to Subaru before my warranty is up (that is a whole other issue. I have not hit 36k miles but have passed 3 years. I called one dealer who said ECU is not covered by the 5 year powertrain warranty but based on some Googling I think he was BSing me).

Any thoughts on this issue? Am I going about this the right way?

Thanks everyone for your thoughts. I wasn't sure what "technical issue" subforum this belongs in so I am posting in the general section for now.
You need two tires the same on the rear end or it will send the LSD into fits under certain condition. It is simple as that.
The electric steering does not compensate for anything. It is a simple assist.
Get a new mechanic since if he is blaming the ECU I am not convinced he knows how a LSD even works.

Stang70Fastback 12-08-2017 02:55 PM
Yeah. This is a mechanical issue caused by having non-matching rear tires. You REALLY need to have the rears matching. At the very least, swap the fronts to the rears.

Also, find a new mechanic before he does something dumb to your car.

covance 12-08-2017 03:00 PM
He was extremely extremely adamant that it was not a tire issue, though I like you both suspect it is, especially since there are no dashboard lights coming up.

He has 34 years as a mechanic and called a friend who works at a Subaru shop to assess the torque sensor issue he thinks there is. He also says he tried switching the front and rear tire on the driver side to match and still got the same effect. However, I am not sure he did this as when I picked up the car the tires were switched back. Not sure why he would switch them back if he did swap...

Are there any potential ECU updates I could be missing if I bought the car in Oct 2014? I do still plan to switch the tires tomorrow and test if the issue resolves itself that way.

covance 12-08-2017 03:03 PM
Quote:
Originally Posted by Tcoat (Post 3014056)
You need two tires the same on the rear end or it will send the LSD into fits under certain condition. It is simple as that.
The electric steering does not compensate for anything. It is a simple assist.
Get a new mechanic since if he is blaming the ECU I am not convinced he knows how a LSD even works.
Hello Tcoat,

In regards to the electric steering not compensating for anything, are you differentiating that from the torque sensor? Asking based on the info on this page:

"The control is provided by a torque sensor that is connected to the steering shaft; a computer tells the mechanism when it is needed to provide additional steering assistance."
https://www.citysubaru.com.au/blog/s...ower-steering/

Stang70Fastback 12-08-2017 03:10 PM
Quote:
Originally Posted by covance (Post 3014064)
Are there any potential ECU updates I could be missing if I bought the car in Oct 2014? I do still plan to switch the tires tomorrow and test if the issue resolves itself that way.
Nothing having to do with what you describe. Even if it was a "sensor" issue, the yaw would be the result of the car intervening to correct what it THOUGHT was a slide. In that event, you'd be seeing lights on the dash, and feeling the power cut / ABS stepping in. The only thing that causes the car to veer in the manner you describe with no lights appearing on the dash is a MECHANICAL issue, such as mis-matched tires. At worst, it's a damaged differential.

covance 12-08-2017 03:18 PM
Quote:
Originally Posted by Stang70Fastback (Post 3014067)
Nothing having to do with what you describe. Even if it was a "sensor" issue, the yaw would be the result of the car intervening to correct what it THOUGHT was a slide. In that event, you'd be seeing lights on the dash, and feeling the power cut / ABS stepping in. The only thing that causes the car to veer in the manner you describe with no lights appearing on the dash is a MECHANICAL issue, such as mis-matched tires. At worst, it's a damaged differential.
If it was a damaged differential I would be having a whole bunch of other problems though wouldn't I?

Stang70Fastback 12-08-2017 03:21 PM
I just read up on that steering sensor. I suppose the sensor could be broken, but I'm still not sure what your mechanic means by torque under acceleration or braking. It's like he's talking about the sensor correcting for torque steer, but these cars don't have torque steer... at least not unless something else is wrong. The sensor really shouldn't have to "compensate" for anything, but who knows, maybe it's fubared???

I would just rotate your tires before trying to dig deeper, though. It's an easy test to do before you start tearing your hair out.

Quote:
Originally Posted by covance (Post 3014072)
If it was a damaged differential I would be having a whole bunch of other problems though wouldn't I?
Eventually, yes, which is why I think that's unlikely. I only really mentioned the diff because it's the only other thing besides tires or stability control that could drag the car to one side under acceleration, and the other side off throttle.

Tcoat 12-08-2017 03:22 PM
Quote:
Originally Posted by covance (Post 3014065)
Hello Tcoat,

In regards to the electric steering not compensating for anything, are you differentiating that from the torque sensor? Asking based on the info on this page:

"The control is provided by a torque sensor that is connected to the steering shaft; a computer tells the mechanism when it is needed to provide additional steering assistance."
https://www.citysubaru.com.au/blog/s...ower-steering/




Yes that is how it works but it is not designed to compensate for abnormal changes in the torque. It is intended to work within specific parameters not adjust for changes due to the LSD.
This is really hard to find the right words to explain what I mean!

bcj 12-08-2017 03:25 PM
The Torsen LSD is a mechanical system that doesn't involve electronics at all.
There are sensors in the twins that mess with the brakes, but not the LSD.

It can be worn or trashed by running different drive wheel diameters - for a long time.
It won't get borked by a few miles, but a few months would cause problems.

[ame="https://www.youtube.com/watch?v=JEiSTzK-A2A"]Torsen Differential, How it works ? - YouTube[/ame]

Tcoat 12-08-2017 03:35 PM
Quote:
Originally Posted by bcj (Post 3014079)
The Torsen LSD is a mechanical system that doesn't involve electronics at all.
There are sensors in the twins that mess with the brakes, but not the LSD.

It can be worn or trashed by running different drive wheel diameters - for a long time.
It won't get borked by a few miles, but a few months would cause problems.
Yes. Running two different tires on the back could very well have the diff act up without ever affecting the electronic traction control.

covance 12-08-2017 03:38 PM
Quote:
Originally Posted by Stang70Fastback (Post 3014076)
...but I'm still not sure what your mechanic means by torque under acceleration or braking...
I Wikipediad torque steer and this paragraph seems to exactly describe what is happening; I bolded the most relevant parts:

"Torque steer is the unintended influence of engine torque on the steering, especially in front-wheel drive vehicles. For example, during heavy acceleration the steering may pull to one side, which may be disturbing to the driver. The effect is manifested either as a tugging sensation in the steering wheel, or a veering of the vehicle from the intended path. Torque steer is directly related to differences in the forces in the contact patches of the left and right drive wheels. The effect becomes more evident when high torques are applied to the drive wheels either because of a high overall reduction ratio between the engine and wheels,[1] high engine torque, or some combination of the two."

I know it says "especially front-wheel drive" cars but maybe my issue is part of the exception :(

covance 12-08-2017 03:41 PM
Quote:
Originally Posted by Tcoat (Post 3014077)
Yes that is how it works but it is not designed to compensate for abnormal changes in the torque. It is intended to work within specific parameters not adjust for changes due to the LSD.
This is really hard to find the right words to explain what I mean!
Trying to clarify: are you saying there is no sensor that would adjust for torque steer in the car via the electronic steering? Or, would torque steer fall within the specific parameters of what the electronic steering should correct for?

Thanks!

Tcoat 12-08-2017 03:42 PM
Quote:
Originally Posted by covance (Post 3014085)
I Wikipediad torque steer and this paragraph seems to exactly describe what is happening; I bolded the most relevant parts:

"Torque steer is the unintended influence of engine torque on the steering, especially in front-wheel drive vehicles. For example, during heavy acceleration the steering may pull to one side, which may be disturbing to the driver. The effect is manifested either as a tugging sensation in the steering wheel, or a veering of the vehicle from the intended path. Torque steer is directly related to differences in the forces in the contact patches of the left and right drive wheels. The effect becomes more evident when high torques are applied to the drive wheels either because of a high overall reduction ratio between the engine and wheels,[1] high engine torque, or some combination of the two."

I know it says "especially front-wheel drive" cars but maybe my issue is part of the exception :(
You have two different tires on a LSD. There is no mystery here. The power steering is not meant to fix this and is not the issue.

Tcoat 12-08-2017 03:46 PM
Quote:
Originally Posted by covance (Post 3014087)
Trying to clarify: are you saying there is no sensor that would adjust for torque steer in the car via the electronic steering? Or, would torque steer fall within the specific parameters of what the electronic steering should correct for?

Thanks!
The torque referred to for the steering is not the torque created by the engine. They are talking about the torque applied when you turn the steering wheel that activates the power steering. The sensors have nothing to do with torque steer. For the steering to compensate for torque steer it would need to turn the wheel on it's own. It doesn't do that.

Cockatoo 12-08-2017 04:13 PM
+1 for tire issue and/or alignment

BirdTRD 12-08-2017 04:26 PM
Quote:
Originally Posted by Tcoat (Post 3014088)
You have two different tires on a LSD. There is no mystery here. The power steering is not meant to fix this and is not the issue.
^^^Listen to him ^^^

covance 12-08-2017 04:39 PM
Will switch tmrw and report back! Thanks all

covance 12-09-2017 01:17 PM
Tires switched. Works absolutely perfect now. Problem solved.

I am absolutely baffled by how certain that mechanic was it was an ECU issue. He owns the garage, owns other gas stations, has owned other garages in the past, him and all his employees are ASE certified etc etc, and he literally talked my ear off for 10 minutes yesterday about how there is no way it is a tire issue.

Thanks fam!

Grady 12-09-2017 03:39 PM
Quote:
Originally Posted by covance (Post 3014416)
Tires switched. Works absolutely perfect now. Problem solved.

I am absolutely baffled by how certain that mechanic was it was an ECU issue. He owns the garage, owns other gas stations, has owned other garages in the past, him and all his employees are ASE certified etc etc, and he literally talked my ear off for 10 minutes yesterday about how there is no way it is a tire issue.

Thanks fam!
Ability to make money and intelligence is not connected.

He obviously knows how to talk a good game with uneducated car owners.

bcj 12-09-2017 03:53 PM
A lot of cars being manufactured now use automatic braking on a slipping drive wheel to *simulate* limited slip the way it should have been done.
That's the computer relation he may have latched onto.

If your mechanic didn't know that we have an actual mechanical LSD that may be what threw him.
They are very uncommon on the great majority of garden variety people movers he's used to servicing.

Ultramaroon 12-09-2017 04:58 PM
Well said, @bcj. I still can't excuse the mechanic for referring to a torque sensor unless he was referring to Torsen, in which case I am even more convinced that he was in full bullshit mode. SMH. Fuck that clown.

guybo 12-09-2017 09:52 PM
Quote:
Originally Posted by covance (Post 3014052)
Hello all!

2 so it unfortunately it does not match the passenger rear tire from a thread pattern and brand perspective.
NO NO NO. you should have bought 2 new rears. Period. You're going to destroy your diff if the damage is not already done.

Of course the pull is from the mismatched tires. Often times, the cheapest way is is the most expensive way out. You have to track down what the mismatched tires messed up.

Tcoat 12-09-2017 11:37 PM
Quote:
Originally Posted by Ultramaroon (Post 3014490)
Well said, @bcj. I still can't excuse the mechanic for referring to a torque sensor unless he was referring to Torsen, in which case I am even more convinced that he was in full bullshit mode. SMH. Fuck that clown.
I knew he was in full bullshit mode when he told Cov that he had tried the different tire on the front and it wasn't the issue. A good mechanic wouldn't have mismatched tires on the drive wheels in the first place. They sure as hell wouldn't take one off the back, move it to the front, test drive it, decide it doesn't work, and then move it to the back again. I am not totally convinced the mechanic even knew the car was RWD from everything that he said.

Tcoat 12-09-2017 11:38 PM
Quote:
Originally Posted by guybo (Post 3014570)
NO NO NO. you should have bought 2 new rears. Period. You're going to destroy your diff if the damage is not already done.

Of course the pull is from the mismatched tires. Often times, the cheapest way is is the most expensive way out. You have to track down what the mismatched tires messed up.
Yes he should have bought matching tires and still should even with them on the front. It doesn't sound like it was on there long enough to have damaged anything though.

Ultramaroon 12-10-2017 12:02 AM
Quote:
Originally Posted by Tcoat (Post 3014607)
I knew he was in full bullshit mode when he told Cov that he had tried the different tire on the front and it wasn't the issue. A good mechanic wouldn't have mismatched tires on the drive wheels in the first place. They sure as hell wouldn't take one off the back, move it to the front, test drive it, decide it doesn't work, and then move it to the back again. I am not totally convinced the mechanic even knew the car was RWD from everything that he said.
100% agree.

covance 12-10-2017 02:18 AM
Quote:
Originally Posted by Tcoat (Post 3014607)
I knew he was in full bullshit mode when he told Cov that he had tried the different tire on the front and it wasn't the issue. A good mechanic wouldn't have mismatched tires on the drive wheels in the first place. They sure as hell wouldn't take one off the back, move it to the front, test drive it, decide it doesn't work, and then move it to the back again. I am not totally convinced the mechanic even knew the car was RWD from everything that he said.
ya this was the largest red flag for me. It's funny because he wasn't trying to get any money off of me for it - he just kept saying to take it to Subaru because we were under the impression it would be warranty work.

Mismatched tires on the rear were probably only there for under two months with <10 miles a day most days.

Willie Swoopes 12-10-2017 09:10 AM
Quote:
Originally Posted by covance (Post 3014085)
I Wikipediad torque steer and this paragraph seems to exactly describe what is happening; I bolded the most relevant parts:

"Torque steer is the unintended influence of engine torque on the steering, especially in front-wheel drive vehicles. For example, during heavy acceleration the steering may pull to one side, which may be disturbing to the driver. The effect is manifested either as a tugging sensation in the steering wheel, or a veering of the vehicle from the intended path. Torque steer is directly related to differences in the forces in the contact patches of the left and right drive wheels. The effect becomes more evident when high torques are applied to the drive wheels either because of a high overall reduction ratio between the engine and wheels,[1] high engine torque, or some combination of the two."

I know it says "especially front-wheel drive" cars but maybe my issue is part of the exception :(
Doesn't torque steer usually apply to front wheel drive because the drive shafts are unequal in length due to the transmission sitting off to one side of the engine compartment? Since they are different lengths they twist at different rates and one wheel gets a bit more torque than the other. I believe the engineers compensate for this by making the unequal length shafts also unequal thicknesses so it compensates for the metal when it binds under heavy acceleration.

Willie Swoopes 12-10-2017 09:11 AM
Quote:
Originally Posted by Willie Swoopes (Post 3014707)
Doesn't torque steer usually apply to front wheel drive because the drive shafts are unequal in length due to the transmission sitting off to one side of the engine compartment? Since they are different lengths they twist at different rates and one wheel gets a bit more torque than the other. I believe the engineers compensate for this by making the unequal length shafts also unequal thicknesses so it compensates for the metal when it binds under heavy acceleration.
But what do I know, I fix computers for a living. :iono:

guybo 12-10-2017 09:16 AM
Quote:
Originally Posted by Tcoat (Post 3014608)
Yes he should have bought matching tires and still should even with them on the front. It doesn't sound like it was on there long enough to have damaged anything though.
2 months, over 200 miles.... I hope not but that's more than enough at highway speeds.

86's have no torque steer at all. There isn't enough torque even if it was FWD. The mechanic may not know this car and may assume that it is FWD (I get that sometimes- people are surprised it's RWD) or is intimidated by a car he knows nothing about but since it's a flat 4 he assumes it's wierd or whatever.

Bottom line- don't go to this hack again with this car.

ermax 12-10-2017 09:30 AM
Quote:
Originally Posted by covance (Post 3014052)
Hello all!



2015 BRZ with 25,000 miles on it. I had my rear driver side tire blow out recently and had to get a new quickly, so it unfortunately it does not match the passenger rear tire from a thread pattern and brand perspective. However, size and approximate wear do match (not many miles on the car).



I took my car in to get an alignment. The alignment was done properly, but the mechanic said he believes there is a problem with my torque sensor. When you step on the gas (for example at highway speeds) there is a significant pull to the left, and when you let off the gas the car goes back to the right. This phenomena does not happen at lower speeds on city streets. The mechanic said this excessive steering torque should be automatically corrected by the electric steering but it is not.



There are no error lights on the dashboard.



I am thinking of switching the front and rear driver side tires to see if the problem goes away (so that the two rear tires will be matched).



I told my mechanic this and he said he already tried this and it did not work. He thinks it is definitely a torque sensor/software issue and that I need to take it to Subaru before my warranty is up (that is a whole other issue. I have not hit 36k miles but have passed 3 years. I called one dealer who said ECU is not covered by the 5 year powertrain warranty but based on some Googling I think he was BSing me).



Any thoughts on this issue? Am I going about this the right way?



Thanks everyone for your thoughts. I wasn't sure what "technical issue" subforum this belongs in so I am posting in the general section for now.


This guy has absolutely no clue what he is talking about. If you have two different tires on the drive wheels you will obviously have pull. If the larger tire is on the rear right then the car will pull to the left on throttle and pull to the right off throttle. It’s very basic physics. Funny he thinks the electronic PS should compensate for this. Hahaha

ermax 12-10-2017 09:33 AM
Problem with torque sensor?
 
The torque sensor on this car is to detect the load we are putting on the steering wheel so it knows how much PS assist to give. There is a calibration process you can do in Techstream. But even if this sensor was off it wouldn’t cause the car to turn one way or another. It would just make the wheel overly heavy or overly light.

ermax 12-10-2017 09:43 AM
Quote:
Originally Posted by Willie Swoopes (Post 3014707)
Doesn't torque steer usually apply to front wheel drive because the drive shafts are unequal in length due to the transmission sitting off to one side of the engine compartment? Since they are different lengths they twist at different rates and one wheel gets a bit more torque than the other. I believe the engineers compensate for this by making the unequal length shafts also unequal thicknesses so it compensates for the metal when it binds under heavy acceleration.


Or have a half shaft the runs from the diff to the other side and mounted to the back of the block then from there it has an equal length axel to the wheel.

cjd 12-10-2017 11:04 AM
Quote:
Originally Posted by guybo (Post 3014709)
There isn't enough torque even if it was FWD.
It only requires a difference between drive wheels. It doesn't need a lot of torque. In this case, there was a difference due to tires. FWD nearly always have it because of different axle lengths.

Its a different beast with a high torque engine, but that doesn't mean its not a thing without.

ermax 12-10-2017 11:17 AM
Quote:
Originally Posted by cjd (Post 3014730)
It only requires a difference between drive wheels. It doesn't need a lot of torque. In this case, there was a difference due to tires. FWD nearly always have it because of different axle lengths.



Its a different beast with a high torque engine, but that doesn't mean its not a thing without.


Agree. I had torque steer on my old Integra which had equal length axels and less torque than the FRS. I will never go back to FWD if I can help it.


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