Truthfully, I'm pretty novice when it comes to recoding. It's a way to mess up stuff and if you don't save your work you could be pretty screwed. Moreover, it's difficult because the available recoding vary from model year to model year. Luckily, our community has a good number of resources. One of the most valueable -- Ryan Johnson. I had the opportunity to discuss some specific tweaks available to MK7 owners. If you own a performance pack car, you especially won't want to miss this one! We cover XDS adjustments, the PP diff adaptation, and briefly hint at a *possible* haldex hack.
What is XDS and XDS+?
From VW directly: "The XDS electronic differential lock is an extension of the familiar EDL function. However, XDS responds not to loss of traction but to the unloading of the front wheel on the inside of the corner when cornering fast. XDS applies pressure from the ESC hydraulics to the inside wheel to prevent it from spinning. This improves traction and reduces the tendency to understeer. The level of pressure applied ranges from approximately 5 to 15 bar. The impression when driving is similar to that of a limited-slip differential in toned-down form. The precise, one-sided build-up of brake pressure makes cornering even sportier, quicker and more accurate." - en.volkswagen.com/en/innovation-and-technology/technical-glossary/elektronische_differenzialsperrexds.html
For more information also check out: en.volkswagen.com/en/innovation-and-technology/technical-glossary/elektronisches_stabilisierungsprogramm.html
The main difference between XDS and XDS+ is the actuation of the front wheel only for the former, vs the front and rear for the latter. As you can imagine, XDS helps rotation, but at a cost of less driver control, and more brake use. On street it can be a life safer, by adjusting the car's yaw, as well as helping it to corner harder. On track it can be an unmanageable system you are fighting. Fortunately, we can adjust the intensity level of XDS (how much brake pressure is applied to the inside wheels) as well as disable it completely.
[Karl]: Diff or no diff, the XDS/XDS+ system also seems to be a hot topic. For a track (circuit) car, do you think the car would perform better with or without it? Besides adjusting the ESC button, do you know of any other XDS tweaks?
[RJ]: I like XDS+ for the streets, I hate it on the track, but that's my personal opinion as a track enthusiast. I disable the system completely when I'm on track tires as I have found that it makes for significantly slower lap times. But if you are on a road course with a non-track worthy tire, the XDS+ system can help create a little more rotation to "artificially" fight understeer. The same goes for a less experienced drivers too, with XDS+ and ESC on, it can make even a Novice Driver look like a hero on some less technical tracks as the system works pretty well and keep you in line if you are pushing the car at only 80% or so.
[Karl]: I 100% agree with this statement here. I can personally attest that learning the MK7 on track was a somewhat wild experience. Trail braking can get you quite a bit of yaw, yet the XDS system can really save your ass and make you look much better than you are. I've personally had people come up to me before telling me they thought I was going to spin, but XDS kept the car in check. In fact, I don't even think it always occurred to me how much rotation was happening. Nevertheless, I've come a long way since that first track day. So if you're adventurous, this might be a hack for you.
[RJ]: You can turn the XDS+ system up via VAGCOM (label “TBD” below) and it feels cool at first, but it is VERY dangerous at high speeds. I personally know two people that have wrecked their MK7’s on off ramps because of this tweak. Leave it at the factory setting or turn it off would be my best suggestion. A couple other VAGCOM tweaks that remove the electrical nannies and really help the car feel more natural on a road course is to set the ABS long coding byte 29 to “08” (which removes ESC when you hold the button by the shifter for 5sec) and disabling the “straight ahead brake stabilization”. The stabilization setting is most noticeable at higher speeds, if you have ever felt your car tug back and fourth this is the system doing some weird stuff behind the scenes and it can make for a sketchy scenario with it on when you are deep in the triple digits.
The PP Diff Tweaks
[Karl]: I recently did an article about the PP diff which you pointed out has the potential for a lot of tuning. Have you made any headway yourself about tuning the PP diff? Do you mind sharing how you did it?
[RJ]: Great article! I just thought that comparing a track built MK7 *insert cheesy smile* with a mechanical diff to a minor bolt-on street focused MK7 PP with the VAQ diff was not quite a fair comparison. The VAQ diff is computer controlled and it's integrated into the ABS system through the BCAN, so in stock form on the PP GTI it isn't very performance focused like the exact same unit found in the GTI Clubsport S and Seat Cupra 280 is (both of which broke FWD Nurburgring records with this setup too). The good news is that with proper VAGCOM adjustment and coding, the diff/pump can be turned up at no cost and performs night and day differently to what you experienced on Brads car. You can take it a step further too and get an even more aggressive tune like the all Seat and VW cup racecars are running, I’m still looking to get my hands on one of these. I'd love for you to come and drive my car if you are ever on the east coast so you can see the difference as your car is setup much more similar to my own.
[RJ]: Here are the settings is the adaption I use and the diff clutches reset procedure:
Possible Haldex Tweak
Previous generations of Haldex systems allowed for actual haldex controllers, like this HPA one: www.hpamotorsports.com/product_haldex.html However, it's been several years since the Mk7's release and nothing has hit the market. Even with VAGCOM, there's not a lot of data. I do have one unverified source, which supposedly increases the default coupling of the haldex.
Coding: Address 22 > AWD > adaptations > wiring logic > increase traction ... Try it, let me know!
Not a ton for me to add to this article! I'm really grateful our community has resources like the forums and members like Ryan. There's tons of other VAGCOM tweaks as well, but most of those are not performance related, and thus, not really in my wheelhouse. I tried to hit the "big three" in this article: XDS, Performance Pack Diff, and Haldex changes. Good luck and happy hacking!