Monitor your wheel speed sensors with the rostech and see if one Sensor drops out or reads a different speed than the others . I've seen a lot of issues with sensors being pushed out by rust. Also make sure the tone rings on the axles have the same number of teeth. And by the way your best is actually great .
Hi Sarah, check the ABS ring on the drive shaft. It might be broken and change position which makes the ABS aktive. This is a common issue when there is corrosion at these ABS rings.
yes as frank says. this is what normal happends when you feel the abs in the pedal at low speed while breaking. it can also happen with magnet rings in the wheel bearings. because at low speeds it can sense a larger cap in the ABS ring and the ABS computer thinks that the wheel are locked and it will break off the breaking pressure
@@SarahnTuned The ABS feed back is most likely cause by a sliver of metal on the magnetic pick up. Or some one used a magnet to remove a peice of metal. Use your computer's data list a pay attention to the wheel speed all should match within 1 mph. The odd ball is the wheel with the problem. The sliver of metal bridges the the square wave form and a magnet will cause the pulse trigger to be wider. Dose not set a code cause data is changing and activates ABS because it thinks one wheel is locking up.. The system is normal just reacting to false data so no code.
As you cleaned the rings did you see any ring dents or something abnormal with them like they are not straight? Im still sure of its a ring thats causing it
Sarah, put the car on the lift and inspect the tone ring on each axle... making sure they're not cracked or damaged to any of the teeth. If you find any of those ... there is your problem.
Check the connection from the vacuumhoses to the brakebooster. This may cause the pulsing. Also compare the signals from the wheelspeedsensors together via VCDS.
OMG, those are ROCK solid measurements. On the third test, a booger landed on the windshield. Why is there only one of you in the world. I could use a 58 year old Sarah.
Great video! Love the science by way of rock measurements, it's exactly good enough! Thank you for giving the credit to the rubber, you're dead on with what the big brakes are doing for you. You could probably even shave another 10 feet off if you disable ABS for the test, it was kicking in(as it should have been) as you were stopping.
I sure others will have already suggested it but,My TT did exactly the same spontaneous abs activation, Fixed it with a full set of wheel speed sensors a cleaning the rusty sensor rings.
For the problem you described that happens when you apply the brakes lightly and you get feedback (ABS actuation). I would check the abs wheel speeds sensors. If one of them is off, it would actuate the abs thinking one of the wheels is slipping.
Stumbled onto your channel because I also went and bought myself a basket case TT and I ran into a lot of similar issues with the 1.8T. I had your ABS problems too. It would ABS regulate particularly often at low speeds regardless of conditions. In the wet ABS would sometimes kick in really late. In my case TWO culprits tag-teamed their way into making my life annoying: 1) The longitudinal sensor was just not working right. No error code though. Not that I saw anyway. 2) Sensors on the wheels themselves were pretty much done (rust mostly, I'd say). Swapping the longitudinal sensor helped the most. But the TT would occasionally just brake 'weird' with some ABS assist when I genuinely felt it shouldn't. Swapping the sensors on the wheels fixed it permanently. If you have any weird braking, just check the sensors at the wheels. Only one needs to be bad for it to do stupid things. As you live in AZ and it is dusty (like here in Cyprus), they can suffer a little bit more than the manufacturer expected.
Using VCDS, Log the four wheels speed (preferably at the graph mode) while driving at low speed (same speed u r having the symptoms) without touching the brakes .. and see which one is reading off, then move to diagnose that corner only rather than guessing
Had a similar issue on my mk4 golf gti, changed sensors, didn’t fix it, changed tone rings, didn’t fix it...... eventually narrowed it down to the steering angle sensor, changed that and it fixed it. Your problem could be any of the above.... good luck hope you get it sorted! Keep the vids coming love watching them
Hi Sarah. I did some reading on German Audi forums what could be wrong with your ABS. The most people had a problem with there sensors not being put in all the way and having not the korrekt distance to the ring. Good luck. Still loving it when you do your thing. Respecting the hard work. Thank you for that. :-)
Each stop was better probably because each stop put more heat into the discs which increased the biting force of the brake pads. Because not all the heat would be dissapated after each stop.
Well, heated tires also grip better which contributes to the progressively shorter stopping distances. Brakes, in general, would tend to fade with heat buildup. So for me, it's the tires.
I wonder if the wheel speed sensor is reading properly at low speeds. I'd also recommended checking the flexible brake lines for small cracks. To check you must flex or move the brake line and look at it with a flashlight. These brake lines are know to dry out crack and eventually burst. When mine was doing this it gave me pedal feedback too, but my feedback most of the time was similar to a warped rotor. Good luck!
Even with all of the issues Sarah is having with the TT, I still want one bad. It would be a hecka fun project car. I've already had my A4 apart a few times. I'm not afraid of a little work.
Hey Sarah papa kirk love the hair colour. That is a very informative video. Thank you for all you do here on your channel and teaching people how to werk on automobiles. And you are awesome.
What a cute little pink laptop. 👧🏼 Looks like it's running Win10. 😲 It's got to be a keeper for running 'basic' _(low graphics/memory wise)_ automotive applications.
Great video, Sarah. Actually, your methods for measuring brake performance ARE fairly scientific. "Consumer Reports' does essentially the same thing, when measuring stopping distance on the cars they test. They don't use rocks of course, but the method is the same. Keep up the good work.
You were pretty damn close for someone that hasn't spent years working towards understanding all this crap, but just because we all love nerdy information, the G251 is measuring acceleration, not horizontal level, kind of the difference between braking forces and sitting still on a downhill slope. So as long as it's zero point is calibrated to no force, it doesn't matter that much if it is sitting perfectly or not. Yaw isn't really measured in the early systems, it's kind of calculated, that's why you need 3 separate sensors for the system. The G202 is purely rotation rate, think of standing in one place, spinning in a circle, where as a yaw rate sensor would be more your feet not moving, and kind of swinging your body around where your feet are, if that makes any damn sense.
@@Dave-fx5zw I guess this wouldn't be Dave Coleman would it? Sounds awfully close to his general scientific nerdisms lol. And yes I still sometimes miss the old Sport Compact Car days
@@SarahnTuned in terms of aircraft yaw, anyway, rotational rate sensor G202 is the same thing. Rotational rate sensors measure rotation around an axis, or you can think of it as rotation in a plane. If you mounted it 90 degrees off, you could measure roll, or the other face of the rubik's cube, pitch. But we know you're correct to think it measures yaw because of its role in the abs system. I think your longitudinal sensor is probably solid-state inside, and it might have an orientation preference.
Hi Sarah, clamping force is increased quite a bit in a hydraulic system by adding surface area, The more metal you push on with the oil the higher the force transferred. So 8 pistons will have more surface than than the OEM system. I don't know how many pistons were in the OEM system but 4 piston to 8 theoretically is twice the clamping force assuming the pistons are all the same size "where they contact the oil" . But you are also right in pointing out that tires make a big difference. Your first stop was horrible because the pads were not warmed up yet as well.
Factory front caliper is a single 54mm piston in a floating caliper. 8 small pistons at say 19mm diameter (no measurement listed, and two sizes on each opposing set) is almost identical piston face surface area. There is no spec on fluid side size, but caliper piston input-output surface areas are usually proportional.
Try getting the tracking done. I used to have the same ABS feedback through the pedal - mine was solved with tracking corrected. Also check condition of the ABS rings
I'm not sure if you already figured the brake issue out with teeter tot but from my perspective it sounds like one of your wheel speed sensors has a slightly larger gap and it's messing with the system in low speed braking conditions which is why the pedal will buzz at low speed braking.
The multi piston calipers should absolutely add clamping force and reduce stopping distance. The smaller pistons allow for more pistons and thus more contact area and more even contact on the back off the pad. The more contact area, the more clamping force. That's why proportioning valves need to be replaced when you go with bbks.
Like the color on your hair! Not 100% but the pulse could be pump related, you have replaced most sensors for abs without any check light so leaning toward mechanical issue in pump.
Reminds me a bit of our blazer that had the speed sensor in the tail shaft of the transfer case go out. Stupid ABS would activate any old time. I got a pretty good scare once when it decided to not let me stop for our driveway.
Watching this again yonks later.... Your science is solid. Do more "Gain access to a track" 2022 style. Science girl...AKA Airforce girl for the win. :)
The ABS Problem could be a broken ABS control unit. Its a known problem that something of the electronic inside brake after years. Here in Germany there a specialized companys who can fix that problem. Maybe you have a company around your homebase who can check and fix the control unit. Or you change it with one of the junkyard. It also possible that the ABS Rings are broken or rusted like hell and the sensor could read it. I had the problem with the control unit at an 1997 Passat and the ABS-Ring on a 1994 URS6. Good luck. You make a great job.
I would recommend using a lab scope on the sensors. Yeah I know you might not have one. I had a car come in a few years ago that had abs kick in in parking lots when braking because one of the abs wires going to the sensor had a broke wire when turning the wheel to a certain point. Only time it would do it was braking in a parking lot when turning. Used the lab scope and scan data to see the sensors drop out. The scan data sometimes doesn't have enough data stream to pick up on the drop outs but the scope will see it.
Hi Sarah, I have a 2003 GTI and am the original owner. I have had the ABS shutter at slow speeds too once. We have the same ESP braking system so this is what I found. Have your front axle shafts checked for security. Also check your front sway bar end links for security, meaning make sure the end links are attached to your subframe. My drivers axle shaft was the problem on mine. Once replaced I’ve never had an issue with it again. German tolerances are crazy tight and it was very hard even to see the difference in abs sensors using the Vag-Com. Hope this helps!
Sarah -n- Tuned Ok, Make sure the Rotor is .3mm from the speed sensors and theirs a Brake pressure sensor G201 that’s under the master cylinder you could look at, let us know what you find out.
Tyres, agreed. And whilst those big brakes might handle heat better, I’d still be pretty disappointed that they don’t make a big step change; standard brakes on all regular VAG cars are rubbish. Hopefully they at least give better feel or something.
I have a GTI with a wierd glitch that its had since I bought it in 2012. If the engine bogs at all especially if the engine is still cold, the EPC light comes on and switches to limp mode. I have been hunting down the source of it ever since. VW/Audi gremlins are hard to kill.
They definitely fail on these, and there's a chance Sarah's has an issue with another part of the system, but that isn't going to be the pulsation. When they fail for wheel speed sensor circuits(and what could be rebuilt) the signal bridge wires fail and will go open circuit. This will set a fault for failing the persistent circuit monitoring check the ESP module performs. For it to pulse, it is seeing a wheel speed of 0, which is different than an open circuit.
The ABS feed back is most likely cause by a sliver of metal on the magnetic pick up. Or some one used a magnet to remove a peice of metal. Use your computer's data list a pay attention to the wheel speed all should match within 1 mph. The odd ball is the wheel with the problem. The sliver of metal bridges the the square wave form and a magnet will cause the pulse trigger to be wider. Dose not set a code cause data is changing and activates ABS because it thinks one wheel is locking up.. The system is normal just reacting to false data so no code.
@@miatakid2 shouldn't that exclude the speeds under 10 kph? As far as i remember ABS on any car does not engage at speeds below 10 kph (or 15, not sure about that) So when she stated that she gets ABS feedback at "creeping speed" that would mean that ABS thinks the car is goind faster than it really does.
@@nirfz not to sure on the kph but here in the states I have seen this happen as low as 5- 10 mph ""parking lot speeds"". . in the shop every time I get this complaint that is what I find. They make this flim paper that has a ferrous fluid that let you inspect the magnetic pick up to see the wagon wheel spokes . this happen a lot especially if somebody replaced a wheel bearing as the pressing in part can shave the hub knuckle . also happen in the rust belt when disassembly some times knocks rust into the magnetic pick up
If you can access live data from your abs module, try n look at the wheel speed sensors while the car is in motion, im sure one of them will have a slight variation causing the abs yo activate. This probably the easiest way to find out which one is the culprit. Otherwise like some other commenters said is to take the tires off and check the abs rings visually. If you have any questions, reply to the comment and I will send you an email.
You may want to check the TONE rings at the wheels. If a nub is broken or the tone ring is cracked, it will give bad information to the ABS computer and cause the abs engaging inappropriately. Good Luck.
Nothing beats a tall slender gorgeous girl in jeans who knows her stuff and yes quirky is what makes this so good Love the hair Love everything actually
I had a car with the same pulsating brake pedal due to the ABS at slow speeds but no ABS light. It turned out to be that one of the wheel speed sensors wasn't close enough to the ring. A small adjustment and it was fixed.
That’s an unusual braking problem, hoping you get it figured out as I’m curious as to what is causing it. Looking foreward to the next video, power up...😊 Hair looks great btw 👍
I was thinking the next time you put the car on your Lift. Start it put it in gear and check to make sure that you don't have a slightly bent axle and along with what the other guys are saying to check your tone rings and your wheel speed sensors and all that stuff too
Check the abs rings for cracks or damage , this is a typical symptom of bad rings and it will normally don't give any fault code registration in the system. You can also check that the sensors are reading the exact speed on your VCDS in the values under the abs system while driving straight forward.
@@SarahnTuned ok, so i assume that the rear abs-ring is mounted on the hub and not on the cv joint right? have you checked it for dents and twists? and have you checked the distance between the sensors and the abs-ring?
@@SarahnTuned ok, then I think I would recommend to change the hubs with the abs-rings first since they where heavily corroded and as you said it only marginally helped wire brushing them. They can be quite sensitive to the distance and also if they have a good build up of rust and dirt.
Hell yeah - try to get a performance meter from some supplier. It will make for a lot of good info. Accel and decel etc. Although - with the correct App - the Iphone can do the same work to about 1-2% accuracy!!!
Strange to see a Sarah video without innuendo.... Love the hair, looked black in the garage, but was lighter in the daylight. I enjoy your scientific...ish approach to the new brakes. But just to let you know, that larger diameter rotor will impart more torque, and does change brake force. Fluid force may be unchanged, but the size of the pads being larger will also change the braking friction area, which also changes the amount of work done by the brakes. So, yes, big brakes are meant to fight off fade at the track, but they do it in multiple ways. Larger friction contact area, larger torque arm, and more mass to move the heat away from the pads, plus advanced cooling methods to remove more heat faster. If you still find that your brakes fade too much for the track time you see, you can use different friction compounds to improve the offgassing that occurs, as well as brakes that bite better when hot, but that might mean changing pads for track days. Forgot to mention, tires don't really change brake distance unless they are sliding.... then those are just bad tires. Good sticky tires compliment breaking, and acceleration, and turning... but great tires and garbage brakes will have you end up in a wall at a track. I am sure you can find an autocross event that you will enjoy taking that TT too. I can't wait till it warms up here for some autox in the CTSVSPORT.
Tyre's do affect your braking (under or over inflated, amount of tread, composition). Same goes for suspension (worn shocks, bushes etc), there's more to braking than just rotors, calipers & pads. There can be a 10-20m stopping difference (depending on road & weather) between a cheap Chinese Tyre & a Hi-end Tyre like a Michelin.
Fantastic video you did great, very scientific and informative thank you. You need to change out the abs control module. Had the same problem with a b5.
