***S3 8L - HALDEX****

[S3Sallie]

Hi all,

Here's my situation. Narrowed down the issue and realized I have a haldex that's acting up.

When I start the car, for the first i would say 500m - 1km i have what feels like a power loss and the traction control light flickers. no boost. There after, things kind of iron out and the car drives normally.

I've gone through this document as a guide but can't figure my issue out

http://www.vaglinks.com/Docs/Audi/TT/Audi_TT_Haldex_SelfStudyGuide.pdf

After investigating the issue. I unplugged fuse 31 (haldex) the car drives normally from the get go.

Troubleshooting so far.

>Diff oil change done around 20 000kms prior.
>Haldex oil Changed regularly (10 000kms). Done another service with the filter change.
>Maf sensor readings are good on measuring blocks
>Changed brake pedal sensor
>Measuring blocks on 051 AWD all reflecting correctly, precharge, brake switches etc
>changed cam position sensor
>Had side shafts and prop checked

I've never had this issue. The car has been running real good. Definitely feels as though the wheels are dragging and consumption is noticeably more when the haldex is connected. But even so, i would think that the jerking/low power issue should be there constantly. It clears out and power returns to normal?

i don't get any lock ups on the full turning circle also no weird noises.

Its definitely got to do with the haldex/AWD system. Can anyone shed some light?

 

[Nilz]

Do a search mate, it has been covered in depth on the forum....

A couple of things to check are the fuse, which you have already done, also check under the car to see if the earth strap has snapped, otherwise it could be that the haldex unit needs refurbing/replacing.

 

[S3Sallie]

Thanks for the response. I've checked the earth strap forgot to mention it. I've done a search, noted that in more than 90% of the cases the guys do a controller change with no improvement. I think the only thing i haven't tried was really giving it a solid launch and see if the scan doesn't pick up a clutch malfunction. Its really strange. the thing that stumps me is that i do maintenance with obsessive accuracy and always keep a log. Only ever used dealer oil in the units. i drive the car daily so i don't hammer it because i love the shape and the car itself. This is the first real issue i'm having with it.

I must say that everytime i change the diff and haldex fluid they still have that nice golden shine to them and no particles?

Just really disappointed at the moment.

 

[<tuffty/>]

Have you scanned for fault codes?

Haldex failure won't cause a loss of power... it generally just spins up the front wheels...the fact the traction light flickers suggests ESP is trying to kick in... does the same happen with ESP switched off?

Sounds more like the system is getting duff info from one of the sensors it relies on as traction light and lack of power is a result of ESP trying to control the car...

I had a similar issue on my A2 when the ABS sensor was playing up... traction control would kick in randomly and ended up replacing the wheel bearing (due to integral ABS sensor ring), sensor and cable to eradicate the issue

Fault codes will help and use VCDS not some generic code reader

<tuffty/>

 

[thegoal007]

yours does sound a bit different from the normal array of haldex issues I researched when I had problems.
Mine was cured with a new controller, but then again I did not have issues on a straight drive. Mine was purely on tight turns. Normally worse during winter and not always consistent. I too would see abs light flicker and power loss when coming out of junctions and going around roundabouts. I just took it very easy knowing I had the issue until i resolved it (it did take me a few years to finally get around to it!)