[saxon_schmauderer]

I love my i8, but i have had aproblem ever since I purchased it that really needs to be addressed. I first realized that there was an issue when at highway speeds the car feels like it is driving on ice.

What I eventually realized (With the help of the Carly app), is that the wheel speeds of my electric motor and the gas motor inb the back are not synchonizing. My speedometer is off by about 3-4mph. The rear wheels are spinning faster than the front. I am basically doing a constant burnout. My last set of rear tires lasted about 1-2000 miles before they were showing wire!

I replaced 2 out of the 4 wheel speed sensors, but the car is still complaining about them when checked with Carly. I used OEM parts. I was wondering if anyon on here knows of any way to test wheel speeds ot to synch the front and rear?

Before anyone recommends it. I haven't been to a stealership my entire life nor have I been to a mechanic. I prefer to do my own work. IM sure this problem is easily fixed, i just need to figure out what I can do to further troubleshoot the problem. I may try to pin out the wires of the wheel speed sensors all the way back to the tcm to see if there are issues. Im not sure.

any help would be appreciated.

Thanks!

-Saxon

[mws]

I am know you compared your speed that is reported by the Carly app to your speedo. I get that.

but what does this mean": "but the car is still complaining about them when checked with Carly. "

do you mean Carly still does not agree with your speedo with the new sensors, or are you saying Carly is saying the new sensors are throwing codes? if codes, be specific and tell us which ones.

I am not imagining the front and rear tires are out of sync like that. Your findings could be a margin of error issue with the Carly app, or from running tires that are not a stock diameter.

First thing I would do is get an alignment check. If you have excessive toe out in front (most cars have none, or some toe in), you "will" feel exactly like you are driving on ice. I know, I've tried it, many times. It is a horrible feeling.

Back when I had a shop, sometimes a drifter I knew would ask me to mess with their front and rear toe to help them start a drift, before going to a class or event.

So, lets get to this being "easily fixed" by you: if the front and rear engines are indeed causing a constant burnout; I am going to encourage you to go to an expert on this one. If that is truly the case, you have serious issues with control modules. You might be able to get someone with a advanced scan tool that can look at wheel speed (I have not tried this, have no idea) front and rear and verify Carly's claims. Then thank them for their time, pay them for the diagnostic, and replace more parts, if necessary.

Follow up and please let us know what it was...

[saxon_schmauderer]

I have been checking the speedo vs gps speed. Obvioulsy there will be a difference, but I feel that 4mph is steep. Carly reports that the wheel speed sensors on the front of the car are not reporting speed. Everytime I drive the car the rear tires smell like I did a burnout. If the car is in full electric mode, the rear tires no longer smell like burnt rubber, nor does the car feel like it is sliding.

I will take it in for an alignment check just to verify everything regardless. That may help with the ice sliding, but i still feel like the wheels are not synchronized. it is a very weird feeling.

Since i have already replaced the wheel speed sensors up front I am going to pin out the sensor cables from the sensors back to the control unit (To make sure continuity).

I will keep you posted.

thanks!

[eswimm]

Originally Posted by saxon_schmauderer

I have been checking the speedo vs gps speed. Obvioulsy there will be a difference, but I feel that 4mph is steep. Carly reports that the wheel speed sensors on the front of the car are not reporting speed. Everytime I drive the car the rear tires smell like I did a burnout. If the car is in full electric mode, the rear tires no longer smell like burnt rubber, nor does the car feel like it is sliding.

I will take it in for an alignment check just to verify everything regardless. That may help with the ice sliding, but i still feel like the wheels are not synchronized. it is a very weird feeling.

Since i have already replaced the wheel speed sensors up front I am going to pin out the sensor cables from the sensors back to the control unit (To make sure continuity).

I will keep you posted.

thanks!

BMWs notoriously read high by about 3mph on the speedo at 60mph. Not saying you don't have a problem, but GPS vs. speedometer reading likely isn't the way to identify it.

[Iain123]

Surely if your front wheels were wanting to go faster the car would always be wanting to accelerate? The car is not permanently 4 wheel drive.

[CnSky]

Considering the engine powers the rear wheels and the electric motor the front when and they are independent I always assumed they're is when in sport mode some sort of software sensor controlled synchronisation.

I would say if your front speed sensors are not working then the front motor can't spool up to match the rear rotation speed or follow a software programmed speed synchronisation map when traction requirements kick in.

I would expect a fault code or drive train error though in this case, also based on all my previous BMWs the speed sensors are part of the ABS system, are you getting ABS errors? what happens if you hold down the intelligent safety button a few seconds to really turn off the all traction system and ABS? Same burning smell?

Does the I8 use reluctor rings to generate an ABS speed pulse could they be badly corroded? Had this before and new sensors were not the issue needed new drive shaft/new rings and hard to diagnose as it's a mechanical not electrical issue.

Finally are you on oem tyres or did you change the wheels or tyre sizes? Could be the issue if your not on oem sized wheels and tyres.

[Manivxr]

Get sensors replaced then do geo alignment. Hopefully that will sort it out

[CnSky]

Any update on this interested to see if you found the problem.

[CnSky]

Any update on this issue?