ABS Fault Code 24 - Wrong Impulsering

[tlk09]

Hi I have a 2000 528iT and I have the trifecta lights. The only fault INPA shows is 24 - Wrong Impulsering. I have removed all 4 wheel speed sensors and cleaned as best i could on the sensor and the rings on back of bearings. Nothing obvious was seen. All my gauges work fine, speedometer is fine, car drives fine. I drove around the block with inpa connected up to 30 mph and all 4 wheels speeds matched within 2 mph of each other the entire time, but the trifecta still pops up after a few moments of driving.I don't understand why the Wrong Impulsering faults doesn't say what wheel. So I figured I would unplug each wheel speed sensor one at a time and see if the code goes away. I cleared all faults then unplugged the driver front wheel speed sensor, drove around block, checked codes and only fault was Driver Front wheel speed high resistance. NO Impulse ring fault. I plugged driver front back in, cleared faults, drove around block, checked fault and Impulering was back. So im thinking the driver front bearing is the issue, to verify I unplugged the passenger front, cleared faults and drove around. Checked my fault and uuugh now the only fault is Passenger front wheel speed high resistance! Plugged passenger wheel speed sensor back in, cleared faults, drove around the trifecta pops up. Checked faults and Im back to Fault 24 - Wrong Impulsering..
I need help, how do I find out which impulse ring is bad? Is the impulse ring the magnetic ring on the back of the wheel bearing or is it something else?

[bmwdirtracer]

Can you watch live data? I'd pull up wheel speeds for all 4 corners, and drive down the street to see which wheel speed is missing, or incorrect.

[tlk09]

I did that, all 4 wheels were within 2mph of each other. Stated that in my first post.

[shadowpuck]

The original post was also a wall of text so details are easy to miss.

Heck - if it was me I might want to play with a scope and look at each tone ring.
I’d wonder if there’s a drop out you could see.

[bmwdirtracer]

Sorry I missed that. Yes, the "impulse ring" is the magnetic ring on the back of the bearing assembly.

Try this: get each wheel in the air. Hit the tire, hard, inwards, at the top, with the side of your fist. Do any of the corners create a metal-to-metal noise when you do this? Any noise / humming when you corner in a particular direction?(Looking for a bad wheelbearing)

All tire diameters the same?

[tlk09]

Yeah my first post was rather long, just wanted to say all the things that I have tried. I bought the wagon around 9 months ago and it only had the DSC light on, about 4 months ago is when the trifecta started. The wheels are staggered 235/35 19 in front and 275/40 19 in rear.
I had INPA on live logging when I was driving, I was by myself though so maybe I could have missed a dropout or something. Ill look into installing some type of video screen capture software while im driving.

[bmwdirtracer]

WAIT: Are you sure about those tire sizes? Because that is WAY WRONG !!!!

The tire outside diameters need to be within about half an inch of each other. You're running tires that are 2" different diameter. That will NOT work.

Please recheck your tire specs. Did you accidentally swap the 35 for the 40, front to rear? If, truly, you're running a 235x35x19 on the front, and a 275x40x19 on the rear, THAT is your problem.

[tlk09]

bmw.jpgThese are what was on car when i bought it. I believe these are Style 95 rims and there are wheel spacers on it. There rear does rub and I have been meaning to buy smaller rear tires maybe 255 or 265's. I always thought that was a big tire size difference also, but I just started diagnosing all the problems with the car and using INPA all four wheel were reading within 2mph.

[tlk09]

BMWDIRTRACER.. I think you might me onto something. I completely forgot, when I bought the car there were 40 series tires on the front but they rubbed constantly. The seller threw in the two 35 series tires. I think the trifecta started around the time I had the front tires replaced. Cant remember because I rarely drove it, had other projects going on. Im just now starting to get serious about this car.

[bmwdirtracer]

tlk:If you had 235x 40x 19 tires on the front, and 275 x 35 x 19 tires on the back, you'd be fine. But if you REVERSE the profile number, and put the '35's on the front, and the 40's on the rear, you're screwed.

Let me explain:

The "235" or "275" is the width of the tire, on a given size wheel, in millimeters.

The "35", or "40", is called the "profile". This number is a percentage relationship between the WIDTH (...275) and the diameter. (i.e. 35% of the width equals the sidewall height)

Tirerack.com offers you the information necessary to find these relationships. It won't be easy for you to follow, at first, but it's just mathematics, no secret formulas.

I'll be glad to help; I've run this relationship across HUGE parameters, for race cars.

But yeah, if your tire sizes are what you said, THIS is your problem/

[shadowpuck]

there goes chris - spoiling all the fun! man, i wanted to scope out tone rings and such!