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Old 12-27-2018, 07:19 PM   #1
Short Bus
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Lifting inside rear tire effect on ABS electronics

Are Volkswagens in general prone to freaking out if the brakes are applied to a wheel that's in the air?

I'm working through a rather bizarre issue with my car after a series of upgrades. Not long ago I upgraded to Eibach Pro-Kit springs and 26/23 mm Eibach swaybars (both set to soft), struts are Koni Sports (Yellows). At the same time I installed Passat spindles and a subframe collar kit. I've also replaced the battery because the old one died.

As I've become more comfortable with the upgrades I've been driving the car more aggressively around corners and lately I've been getting an "explosion" of ABS, traction control, and red "brake" light flashing with associated loud beeping, followed shortly by the "airbag" light illuminating. I can shut off the car, start it again, and all the lights clear out.

I've tested traction control, XDS, and ABS systems independently before and after the error lights come up. Prior to the warning light explosion all systems function, after the lights come up they do not function.

What I noticed a few minutes ago was that the lights were coming on after aggressive low speed maneuvers, think autocross. A reliable way to duplicate the issue is around a nearby, slightly off camber traffic circle, and occasionally around 90 degree right hand turns. These are the kind of corners that cause most FWD cars to lift the inside rear tire when driven aggressively, and in the case of the 90 degree right hand corners it's possible that it's happening as I'm trailing the brakes to modulate load on the front tires.

I've ordered an OBDeleven so I can check codes and see what's going on with the wheel speed sensors, which I've already unplugged, removed, and cleaned. I also need to order a GoPro mount so I can see if I can tie the errors to lifting a tire.

Sorry if this is a well known issue and I never got the memo. I ran some searches and came up empty, mostly a lot of information about troubleshooting wheel speed sensors; which may still be my actual issue, but I won't know for sure until my OBDeleven arrives

Last edited by Short Bus; 12-27-2018 at 08:52 PM.
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Old 12-27-2018, 07:23 PM   #2
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I don't think it has anything to do with the things you've done to the car. You just have a bad abs sensor I bet. I've been seeing these lights off and on for the past few months, just haven't taken the time to fix it.
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Old 12-27-2018, 08:37 PM   #3
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Originally Posted by sterkrazzy View Post
I don't think it has anything to do with the things you've done to the car. You just have a bad abs sensor I bet. I've been seeing these lights off and on for the past few months, just haven't taken the time to fix it.
Normally I'd be inclined to agree with you, but I just went for an hour long drive without the aggressive cornering and the car was perfectly happy. You might still be right, but because I can more or less duplicate the issue when I want to I think there might be more to this.

So what would happen if I put the car on stands, put it in gear and engage the clutch so the car thinks it's in motion, and then quickly tap the brakes gently enough so that it doesn't stall the engine? Is the ABS controller going to notice that the front wheels are spinning while the rear ones aren't and then treat me to a light show?

If I get a light show with that experiment it makes me think the issue really is that I'm lifting a wheel while I'm trailing the brakes. Because I've lowered the car beyond it's happy "roll center" place, it means that the front suspension is going to want to roll more than it did on the stock springs. That combined with a dramatically stiffer rear sway bar without dramatically stiffer rear coil springs it's possible at the inside rear isn't rebounding as fast as the front outside is compressing.

My to-do list:

1. lift the car and try to duplicate the issue
2. adjust rear dampers for less rebound; I don't recall what I have them set at but they may be too stiff and not allowing the suspension to articulate properly
3. set front anti-roll bar to stiff and hope it reduces body roll enough
4. wait for my OBDeleven to arrive

I hope I don't have to resort to #3 to fix it, I'm really enjoying how the car corners at low speeds. On the stock springs and bars you need to have very slow, gentle hands to get around low speed corners quickly. With the Eibach springs and bars the front end really hooks in around corners nicely.
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Old 12-27-2018, 08:46 PM   #4
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lol, I missed the part about it happening during steering. I saw you said it happens randomly and then pretty much just read everything after that and missed most of what was said before. It's always only when steering? I see...I get the lights only when I start my car, but it doesn't always happen, so ignore me.
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Old 12-27-2018, 08:55 PM   #5
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lol, I missed the part about it happening during steering. I saw you said it happens randomly and then pretty much just read everything after that and missed most of what was said before. It's always only when steering? I see...I get the lights only when I start my car, but it doesn't always happen, so ignore me.
Sorry! I can see why you’d come to that conclusion, I edited the post to clarify.

Yeah, it only happens while the car is in motion and during steering. The lights are never on the second I start the car. The lights only come on when the car is in motion.
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Old 12-27-2018, 09:08 PM   #6
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It seems like if that was a thing these cars had problems with it'd be pretty well known. I know they have faulty abs sensors though, so I wouldn't rule that out.

The lights trigger even with traction control off? I guess that's not really truly off unless you do the esp defeat though.
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Old 12-27-2018, 09:36 PM   #7
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Originally Posted by sterkrazzy View Post
It seems like if that was a thing these cars had problems with it'd be pretty well known. I know they have faulty abs sensors though, so I wouldn't rule that out.

The lights trigger even with traction control off? I guess that's not really truly off unless you do the esp defeat though.
The "ESP OFF" button in my car only really disabled traction control , leaving ESP fully engaged (I assume most USDM MKVIs are the same?). I've learned to just drive around it over the years, if anything the car has taught me that I can open the throttle a lot earlier than I'd normally think. Most of the time if stability control kicks in it's because I didn't open the throttle soon enough and the car detected more rotation than it liked.

That'll be a nice bonus of having the OBDeleven though, I'll be able to see about coding in the full ESP defeat. I guess it'll come down to what specific ABS pump my car is equipped with.

I definitely will not be ruling out bad ABS sensors. The front sensors were clean because I had just reinstalled them with the Passat spindles, but the rears were pretty nasty. After cleaning them it seemed like I had to work harder to make the system fail, but that might just be in my head. I'll be sure to look for faults when I can.

Another thought I've had is that I'm really disappointed in the Konis on a lowered car. They were fantastic on stock springs, but with less suspension travel they really need more bump stiffness. It's an annoying trade-off, the car really feels like it has a lot more bite at corner entry with the new springs and bars, but I guess the front is rolling in so quickly that the rear can't keep up. From a comfort point of view more bump stiffness would be nice as well, because the car crashes over big bumps now.

I don't think I'll be sticking with the Koni/Pro-Kit combo for longer than I have to. I really like how the car corners but I'm not happy with the negative side effects.
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Old 12-28-2018, 02:10 PM   #8
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It’s starting to look like the winner might be a bad wheel speed sensor.

I’ve driven the car for a couple of hours since first posting this and while driving like a sane person I had no issues. Today towards the end of the drive I took a couple of aggressive low speed 90 degree right hand turns and was treated to the light show. Difference is now the lights don’t go away when I turn off and restart the car.

I’ll post another update when I can run diagnostic scans.
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Old 12-28-2018, 02:33 PM   #9
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It makes sense that it would be from the wheel lifting. These systems flip out in any situation that creates a mismatch between wheel speed and vehicle speed. I got my Passat stuck in mud once, and after a couple moments of spinning out, the whole dash lit up like a Christmas tree. ABS, ESP, steering wheel symbol, airbag light, everything. Pretty much every system relies on knowing how fast the car is moving, so if they get conflicting inputs, they turn off and warn you.
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Old 12-28-2018, 03:08 PM   #10
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It makes sense that it would be from the wheel lifting. These systems flip out in any situation that creates a mismatch between wheel speed and vehicle speed. I got my Passat stuck in mud once, and after a couple moments of spinning out, the whole dash lit up like a Christmas tree. ABS, ESP, steering wheel symbol, airbag light, everything. Pretty much every system relies on knowing how fast the car is moving, so if they get conflicting inputs, they turn off and warn you.
The ABS electronics are the one thing that frustrates me about this car. It's like the engineers who coded the ABS weren't talking to the engineers that sorted out the suspension because the two systems just don't get along. Even on the stock suspension when you hit the fun point and the car starts to rotate the brakes kill the fun right as your foot is moving to catch the car with the throttle.

The mechanical engineers created one of the best handling FWD cars out there, then the engineers designing the ABS made the best parts of their work inaccessible.
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Old 12-28-2018, 06:09 PM   #11
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I could go on all day about my grievances with ABS systems as a whole...
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Old 12-29-2018, 11:43 AM   #12
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Yes the darn nanny is a very strict one for sure. This is the first car I have ever had with stability control & traction control. I find traction control not terrible & at least it can be turned off. Stability control seems to override everything. Not a fan.....

My suspension is oem with the exception of a SPM 23mm rear swaybar. I don't find any of the problems you seem to be having. Although on a dirt road while trying to do a handbrake turn it goes absolutely apoplectic. IMO under the right condition that darned thing could in fact cause a crash rather than prevent one. There really needs to be a way to turn it off.
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Old 12-29-2018, 03:40 PM   #13
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Quote:
Originally Posted by Short Bus View Post
Are Volkswagens in general prone to freaking out if the brakes are applied to a wheel that's in the air?

I'm working through a rather bizarre issue with my car after a series of upgrades. Not long ago I upgraded to Eibach Pro-Kit springs and 26/23 mm Eibach swaybars (both set to soft), struts are Koni Sports (Yellows). At the same time I installed Passat spindles and a subframe collar kit. I've also replaced the battery because the old one died.

As I've become more comfortable with the upgrades I've been driving the car more aggressively around corners and lately I've been getting an "explosion" of ABS, traction control, and red "brake" light flashing with associated loud beeping, followed shortly by the "airbag" light illuminating. I can shut off the car, start it again, and all the lights clear out.

I've tested traction control, XDS, and ABS systems independently before and after the error lights come up. Prior to the warning light explosion all systems function, after the lights come up they do not function.

What I noticed a few minutes ago was that the lights were coming on after aggressive low speed maneuvers, think autocross. A reliable way to duplicate the issue is around a nearby, slightly off camber traffic circle, and occasionally around 90 degree right hand turns. These are the kind of corners that cause most FWD cars to lift the inside rear tire when driven aggressively, and in the case of the 90 degree right hand corners it's possible that it's happening as I'm trailing the brakes to modulate load on the front tires.

I've ordered an OBDeleven so I can check codes and see what's going on with the wheel speed sensors, which I've already unplugged, removed, and cleaned. I also need to order a GoPro mount so I can see if I can tie the errors to lifting a tire.

Sorry if this is a well known issue and I never got the memo. I ran some searches and came up empty, mostly a lot of information about troubleshooting wheel speed sensors; which may still be my actual issue, but I won't know for sure until my OBDeleven arrives
The 23mm Rear bar set on the softest is too soft, it has little to do with lifting the inside rear tire. The Passat Spindles have shorter arms so they increase the steering ratio which is out of sync with the steering angle sensor and what the ESC compter expects, so the system is overly sensitive. Quick movement of the steering wheel will cause the ESC to engage so you will have to be smooth with your steering as well as brake inputs while turning. I could be wrong but I think the steering rack ratio on the '10 cars is a bit quicker than on post '11 cars.

The race teams use the lighter Passat Spindles not for the quicker ratio but to reduce unsprung weight, has several benefits but over-all they gain better dynamics but more importantly loose less time from mass induced understeer and can put the power down better as the geometry is setup correctly not to counter-act understeer BUT I guess the key is that they turn off the Nannies.

EDIT: Since you ordered the OBD11, you should try doing a Steering Angle Calibration that may help if it wasn't done before properly after your mods; it might help with the over-all sensitivity.

Last edited by MLue1; 12-29-2018 at 07:04 PM. Reason: comment
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Old 12-29-2018, 07:18 PM   #14
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I could go on all day about my grievances with ABS systems as a whole...
My first few sports/sporty cars didn't have any of these systems, so I can still handle braking at the limits of traction without ABS and I can live without stability control or traction control, but... I'm still happy that they exist. I just wish Volkswagen had put a little more thought into the system on this car. Like, maybe if my foot is on the throttle and the car is sliding, I'm doing it on purpose and am not at all interested in being "saved."

If I had any idea how to recode the system on the car I'd happily do it, but I don't know the first place to start.

Quote:
Originally Posted by 1ashchuckton View Post
Yes the darn nanny is a very strict one for sure. This is the first car I have ever had with stability control & traction control. I find traction control not terrible & at least it can be turned off. Stability control seems to override everything. Not a fan.....

My suspension is oem with the exception of a SPM 23mm rear swaybar. I don't find any of the problems you seem to be having. Although on a dirt road while trying to do a handbrake turn it goes absolutely apoplectic. IMO under the right condition that darned thing could in fact cause a crash rather than prevent one. There really needs to be a way to turn it off.
Thanks for the input. With that big bar on the front combined with the stock bar, I'd think that you'd end up with a similar issue. Either that or these cars are extra sensitive to roll center changes and being at stock height makes all the difference here.

Quote:
Originally Posted by MLue1 View Post
The 23mm Rear bar set on the softest is too soft, it has little to do with lifting the inside rear tire. The Passat Spindles have shorter arms so they increase the steering ratio which is out of sync with the steering angle sensor, so the system is over sensitive.

The race teams use the lighter Passat Spindles not for the quicker ratio but to reduce unsprung weight, has several benefits but over-all they gain better dynamics but more importantly loose less time from mass induced understeer and can put the power down better as the geometry is setup correctly not to counter-act understeer BUT I guess the key is that they turn off the Nannies.

EDIT: Since you ordered the OBD11, you should try doing a Steering Angle Calibration that may help if it wasn't done before properly after your mods; it might help with the over-all sensitivity.
That's an excellent point regarding the steering angle calibration. After I installed all the parts I checked the toe with toe plates and the rear was still spot on perfect, meaning the thrust angle was unaffected. The front toe was hilariously out of spec, about an inch positive on both sides of the car (changing the length of the steering arm on the spindle will do that). All this to say... adjusting the toe myself in my garage combined with your observation regarding the Passat spindles probably means that I really need to run that calibration.

The thing with the rear bar is that because Eibach didn't publish the ProKit coil spring rates I don't know if the soft setting of the bar is too soft or too stiff. Because the ProKit springs are dual rate I'd suggest that it's possible that as the rear inside corner decompresses the spring hits the "soft" half of the spring, which may not be stiff enough to decompress completely against a swaybar that's loaded at the other end of the bar. It's also possible that the rebound setting I have dialed in is overly restrictive for the "soft" rate of the spring, making the issue worse.

I don't like guessing, but I also don't care to remove the rear springs and rear bar and attempt to measure their lbs/in of travel in my garage.

If I want to keep the inside rear on the ground at corner entry I have to either increase suspension articulation at the rear of the car (less bar stiffness / more coil spring stiffness) or reduce body roll at the front of the car (increased roll stiffness, raise roll center). But this is another assumption, I don't know if I'm actually lifting off, because my issue went from "intermittent" to "permanent" and I've not broken out the GoPro to have a look.

Still though, it's normally not at all a problem to hike the inside rear of a front wheel drive car at corner entry. Go to any autocross and most FWD cars are hiking the inside rear around every corner.
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