wheelmanbg

Quattro problem?
This has been going on for a little while. When driving on slippery roads and/or in bad weather the car will sometimes jerk/jolt like the drivetrain is seizing up. It won't do it under full throttle nor will it do it under no throttle. It only happens with light throttle. It happens at any speed, anywhere from 20 mph to 80 mph, any rpm, any gear.
It's only a split-second jolt and it somewhat feels like the ESP is trying to shut things down; however, turning the ESP off does not cure it.

This started about a month ago. It hadn't done it since I changed the fuel filter but also the roads have been dry. It snowed last night and today it's doing it again. It's not temperature related...

The car also feels like it's wanting to drift sideways when driving on mixed roads (ice/snow/dry). Feels like it's swaying to one side or the other, almost as if the wind is pushing it. I had it aligned and that seemed to resolve this issue.

I have no clue what it could be...

No current codes but I did see a steering angle sensor code a few weeks ago. I had the fluids checked and the tranny was low but it's still doing it after the tranny was topped off.
It's a 2003 A4 Quattro 3.0L 6 speed manual

600whpA4

Sounds like the EDL which is the ABS trying to slow down a wheel that is spinning faster then the others. ESP closes the throttle to reduce power. Turning off the ESP does not turn off the EDL.


Problem is EDL should only kick in at low speeds.

wheelmanbg

That makes total sense because that's exactly what it feels like.

How would I go about fixing it??

s4master1

forgive my ignorance but don't know where is the edl on a 03 3.0 6 speed?
can you elaborate please?

ALLDATAdiy INFO

The Electronic Differential Lock?

s4master1

correct, can you tell me what it is/where it is on this particular model please?

lyleswk

From a little searching, EDL is simply logic in the ABS system that will apply the brakes to a spinning wheel based on the wheel speed sensors up to 50 mph. This helps with stability in slick conditions. You noted that you only had steering angle sensor codes, could not find any info that indicated the steering angle sensor provided any input to this. So, based on this and the lack of wheel speed sensor codes (please someone correct if wrong about the steering angle sensor), I have to wonder if you are simply feeling normal "slick" conditions. Can you be more specific on the road conditions you are talking about.

600whpA4

EDL is just part of the ABS and the ABS sensors located at each wheel hub.

wheelmanbg

I've had the jerking occur at speeds above 50mph. It was doing it pretty violently on the interstate while going 70-75mph. It feels like the drivetrain is locking up for about 200 miliseconds, then back to normal. It seems to do it when it's snowing out and/or roads are covered in snow. Is there a way to track what the ABS is doing while driving? Would VAGCOM be able to do that? If I could log what happens when the jerking occurs, it would help figure out this issue.

Thanks for the replies, they are appreciated!

lyleswk

First, I am not aware if VAGCOM can log ABS functions. To my knowledge, it is only engine parameters.

Second, since it happens in snowy conditions, I would lean toward "normal" for snowy conditions. I have not had a lot of experience with the Gen IV quattro in snowy conditions (about 4 drives), but it seems reasonable that because we have higher levels of overall vehicle grip capabillity, that when physics takes over and it does go, it does it more "abruptly" and then just as "abruptly" recovers once grip returns. Think of the early 911's; when they snap oversteered, there was no stopping it. Difference for us is that the "system" starts moving torque around to try and recover grip without us doing anything except wondering what is going on. Last winter in the snow, I do vaguely remember this "skidding" feeling, but attributed it to the 6+ inches of snow and running on all-seasons. I drove a Gen II 4000 quattro in a lot of snow and never noticed this, but that is a very different system. I have also driven a Mercedes 4matic in a lot of snow and have noticed some "jerking" in it. Again, that system is quite a bit different as well so not sure I can make any relationships.

Last, the only other thing that I could think of is the torsen center diff is behaving "abruptly" and may need new fluid. When is the last time you changed your tranny fluid?