Oddball Things- Haldex Duty Cycle S3/MQB

   #1  

morris39

Verified VCDS User
Verified
Joined
Mar 4, 2020
Messages
82
Reaction score
7
Location
Canada
VCDS Serial number
C?ID=395084
I am curious about reason for the Haldex maintenance interval (3 yrs, not miles) and claims on Audi forums that the Haldex pump fails and filter clogs badly and is not on maintenance schedule. I logged the Haldex pump PWM signal over a 20 min. period in my typical suburban drive at near peak traffic on dry roads, 82 deg F, car fully warmed up.
Here is what I got, values are the measured values divided by the max indicated reading:
MAX=1.00;MIN= 0; MEDIAN=25;AVERAGE= .27.
Max indication was 60 (units?) at 3000 rpm launch on a road with a bit of gravel and front wheel spin which I guess is close to max clutch engagement.
It seems that my Haldex is not working very hard under these conditions, but only under hard acceleration. So the complainers are probably hooligans and deserve their results. BTW this is only the 4th launch in 20k miles and the 1st was a fail. Interestingly Autoscan summary gave no DTC's but Controller 02 listed 11 DTCs, all gears inaccessible ( not fact) and implausible signals. That happened 2X.
What are the units for the time stamps and the PWM signals?
 
   #2  

PetrolDave

Verified VCDS User
Verified
Joined
Dec 16, 2014
Messages
3,790
Reaction score
3,789
Location
South Molton, UK
VCDS Serial number
C?ID=1423
There has been a lot of discussion recently on the Octavia III forum of briskoda.net about Haldex filter clogging with some scary pictures of the filter almost totally covered in 'goo' after only a few thousand miles of normal (not crazy) driving.

Seems that some characteristic of the Haldex fluid makes it more susceptible to forming 'goo' than normal oils and lubricants.
 
   #3  

Jack@European_Parts

NostraJackAss
Joined
Jan 29, 2014
Messages
20,381
Reaction score
8,728
Location
Montgomery, NY, USA
VCDS Serial number
C?ID=57337
Installing a cooler and extended sump/pump and removal of filter to use a bypass + filter externally to vacate all heat solves all HALDEX issues instantly & permanently.

HEAT IS THE ENEMY
 
   #4  

morris39

Verified VCDS User
Verified
Joined
Mar 4, 2020
Messages
82
Reaction score
7
Location
Canada
VCDS Serial number
C?ID=395084
@PetrolDave,Jack
I've done another log and confirmed that my Haldex is not working very hard, typically 15% duty cycle and clutch temperature was very steady ~ 45C or 13 deg rise over the ambient. Pump current and PWM did not correlate exactly probably due to the sampling rate. I used 1/2 second instead of the default 55 msec. BTW using 500msec rate took 2x longer to do AutoScan, 2min.
Maybe the Haldex fluid is not chosen for lower friction but for better clutch bite. Low friction motorcycle oils have clutch problems as the gearbox/clutch/sump share the same oil.
 
Top