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E85 / E86 Z4 (2003-2008)
E85 Z4 Roadster, E86 Z4 Coupe, E85 Z4 M Roadster, and E86 Z4 M Coupe talk with our BMW gurus here.

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  #1  
Old 07-13-2013, 11:30 AM
2 Seater 4 Me 2 Seater 4 Me is offline
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Question New DSC Issue

I've seen and read a lot about DSC issues but have not seen anything like what I'm experiencing. 2003 Z4 3.0 SMG with 18" Wheel / Sport Option 140,000 miles / daily driver.

The car drove and handled perfectly. No issues. Put new tires (Yokohama Avid Envigor) on the rear and first drive the DSC started going off in corners. Speeds were 15+ MPH less than normal and DSC was engaging. Couldn't get the car in the shop right away but everybody said it was the tires. Inspected the car, found faulty RF strut (Bilstein HD) and replaced - no change. Read about bushing issues, replaced RTABs and FCABs - no change. Bought new rear tires (TOYO Extensa HP) and replaced along with weighted 4 wheel alignment - no change. Cleaned wheel speed sensors - no change. Disconnected battery and did lock-to-lock check on steering - no change. Mechanics can find no worn suspension parts or problems.

The car has unusual body roll and the steering feels loose. It also feels like there is a lot of weight transfer going on during hard acceleration and breaking. I'm out of ideas and have a feeling I'll soon be out of money. I'd greatly appreciate some direction.
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  #2  
Old 07-13-2013, 12:00 PM
pokeybritches pokeybritches is offline
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What size are your front and rear tires?
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  #3  
Old 07-13-2013, 12:04 PM
2 Seater 4 Me 2 Seater 4 Me is offline
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Fronts are TOYO Extensa HP 225 40 18 (90%) - Rear are same 255 35 18 (new). I've mixed and matched tires for the entire 140k and never felt anything like this.
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  #4  
Old 07-13-2013, 12:34 PM
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Randy Forbes Randy Forbes is offline
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Excessive body roll and squat/dive point blame to bad shocks.

As a point of reference, on the 98 - 02 Z3/M versions (where most of my experience lies) the OE shocks are toast/blown in under 42,000 miles.

Normally, shocks wear out so progressively, that you don't realize how bad they are until they're replaced. Don't rely strictly on a "bounce test" for shock evaluation.

Are they the source of your DSC problem? Hard to say, but since the tires and suspension work together as a system, the new(er) tires may have brought out the short-comings with the shocks.
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  #5  
Old 07-13-2013, 01:40 PM
2 Seater 4 Me 2 Seater 4 Me is offline
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Thanks for the input. I checked all of the shocks/struts (Bilstein HDs) and found the RF leaking. Bilstein replaced it under warranty. All four had/have 20k on them. The other three were in good shape. I disconnected the bottoms and compressed them and they were like new. I'm reading now about the steering angle sensor and getting a little nervous.
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  #6  
Old 07-13-2013, 02:43 PM
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Clearancediver Clearancediver is online now
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New DSC Issue

Have you checked your tire pressures and re-initialized the tire monitor switch (tire symbol) on the center console... It's linked into the DSC system.


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  #7  
Old 07-13-2013, 04:00 PM
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shipkiller shipkiller is offline
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There are several things that could be the culprit. Along with with Randy said, there are several known problem children that have some issues from time to time. Those are mainly the wheel speed sensors in each wheel. Sometimes they can get dirty or one or more can be faulty. There is also the DSC Sensor. This is located under the passenger seat carpet and it registers the transverse acceleration and yaw rate. You mentioned the SAS (Steering Angle Sensor). If the SAS is not calibrated (zeroed) properly, you can and will get all kinds of strange DSC behavior. Every time you have an alignment performed, the SAS is supposed to be zeroed. Some shops do not know to do this. The Hunter Machines specifically tell the operator that this must be done. In the Roadster, I had this happen. I had an alignment, sans no SAS zero, and the car was all kinds of strange.... When to another shop, they performed another alignment, reset the SAS and the car was great. I am not saying that this is your issue. It is just a possibility. In all actuality, unless you want to just throw parts at the car to see if something fixes it, I would take it to a BMW specialty shop, the Dealer or if you know anyone with the INPA software on a laptop. With INPA you can monitor in realtime what the sensors are showing and it will give you any error codes if they were generated, and zero the SAS.

The RPA (Tire Deflation Warning) is calculated by the DSC electronics (it uses the wheel speed sensors to do this) but the DSC itself does not use this data for DSC intervention.
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  #8  
Old 07-13-2013, 05:18 PM
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Randy Forbes Randy Forbes is offline
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Interesting thing about the SAS; pretty sure the Z3/M either doesn't have one, or it's much more forgiving. Case in point; I've pulled the steering rack off (not completely off, just enough to remove the oil pan) probably fifty (>50) 01/02 ///Ms and never had a thought about the SAS. I've done the same connecting rod bearing job on two (2) Z4/M Coupes, and the issue never came up with the first, but when I did the second one, upon starting the engine, there was a Check Engine, ABS & DSC light/faults. Turns out the SAS was reading "360*" So upon reassembly, the splines (on the steering column/steering rack) were lined up perfectly__I always mark them__but the SAS mistook "0*" for "360*"

Fortunately, my Autologics diagnostic computer is capable of performing the SAS realignment, which cleared all faults.
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  #9  
Old 07-13-2013, 05:25 PM
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Off topic.

Randy, I just got the car back from having the rod bearings replaced. My right engine mount was TOAST (literally in two pieces). I replaced the mounts with the Vibra-Technic mounts.. The car is good again.

Back on topic.....

The pre-face lift Z4's use a modified E46 DSC. The face lift cars use a modified E90 DSC.
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Last edited by shipkiller; 07-13-2013 at 05:27 PM.
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  #10  
Old 07-14-2013, 05:33 AM
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GeorgeT GeorgeT is offline
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I had the same issue - it went away when I replaced the battery. Weak batteries cause several "false" warnings.
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  #11  
Old 07-14-2013, 07:28 AM
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Whenever a tire is changed the steering angle sensor should be recalibrated. Even with the key out of the ignition, the steering angle sensor is still functional. If you for example, take your front wheel off, and turn the steering wheel while it is off and car up on jacks, you might get all sorts of DSC errors. I know this from experience. Follow SK's advice above.
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  #12  
Old 07-14-2013, 11:51 AM
siwilson siwilson is offline
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Interesting topic!

I had the rear tyres replaced on my S54 Z3M about a year ago. Prior to this the car stuck to the road, but after it feels like I have oversteer and the DSC light flashes way more often. Especially on long high speed bends. At first I thought it was just that the tyres were new and I needed to give them a few miles. 12 months and 2000 miles later the problem persists.

I replaced Goodyear Asymmetric 1 with Asymmetric 2.
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  #13  
Old 07-14-2013, 01:36 PM
2 Seater 4 Me 2 Seater 4 Me is offline
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Thanks for all of the input. The SAS was NOT calibrated after the alignment. I tried the lock-to-lock technique I've read about but it didn't make any difference. I'm trying to get the car into the local Euro Car specialist this week. Also will try, based on GeorgeT's comments, putting a charger on the battery tonight and see if that does anything. I'll let all know the results.
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  #14  
Old 07-15-2013, 05:05 PM
2 Seater 4 Me 2 Seater 4 Me is offline
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Took the car to the Euro specialists. No codes, no mechanical issues and the SAS was correct. They called their tire guy and he said the tires could cause this due to tread pattern and depth and that I need to scrub off some tread and the problem will go away. So Yokohama's and Toyo's both caused the same issue. I have no idea why the previous Goodyear's, General's, Continental's made the car feel like it was on rails and these make it feel like it's on the ocean. I'll start scrubbing tomorrow.
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  #15  
Old 07-16-2013, 06:56 AM
Jstic Jstic is offline
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Have you taken the car to a BMW dealer, lots of independent mechanics are not good with BMW software.
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  #16  
Old 07-16-2013, 03:31 PM
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Have not been to a BMW dealer. The nearest one is 100 miles away. Today I drove the car with stability control off, but traction control still on. It still engaged during turns just as before. Also, just recalled that the front wheel speed sensors has metal shavings on them at the magnetic tip. Does anybody know if either of these mean anything? The car goes back in the shop tomorrow.
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  #17  
Old 07-16-2013, 05:03 PM
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Clearancediver Clearancediver is online now
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New DSC Issue

I would clean the wheel sensors and see what happens. 10 minute job per wheel to do that in your garage. Eliminating a potential cause is always useful when diagnosing an issue.


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  #18  
Old 07-17-2013, 07:21 AM
Jstic Jstic is offline
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The magnetic shavings are normal. Those sensors have a magnet and coil to read the teeth on the tone ring. Magnetic particles are invevitable.
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  #19  
Old 07-25-2013, 05:30 PM
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Here's an update. It turns out I was getting tread squirm from the all-season tires. I drive about 100 miles per day on some twisty roads. I inflated the tires to 38 psi and turned off the DSC and traction control and used the throttle to help steer. I am at about 500 miles on the tires and every day the car feels a little tighter and corners with more stability. Still not where I want to be but I'm starting to love the car again. Thanks for all of the input. After this, no more all-season tires for me.
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