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XGC75 - One for the Road

XGC75

XGC75

Go Kart Champion
Speaking of, I just bought some RAAAAAAIHMMZZ.

This is actually a pretty good savings for me:
- For one, I need to buy a set of hub rings after I broke one trying to pry it off the hub as I changed to the winters this fall.
- Second, I need two center caps for the nurburgrings.
- Most importantly, I need summer tires. I think I posted the status of the PSS's after the track day at Autobahn earlier. They're not even good enough to trust on a drive down to Tire Rack to get new tires fitted.
- Lastly, I'm sick of steelies for winters.

I wanted to work out a way to get into some 18's for the daily set and at the same time relegate the Nurburgrings to my winter 17"set. What I found was a set of TSW Interlagos, 18x8 ET45 5x112, silver with machine-cut face. They're about 18lbs a corner, only a few ounces more than the Nurbs at 17x8. They're wrapped in Falken tires, which isn't my preference, but according to reviews they're quiet and comfortable if a little light on the mileage capability. All in all this setup provides an easy solution for the center cap, hub ring and tire problems all while dropping the steelies for about $100 more than it would have cost to buy new summer tires, hubrings, center caps now and cheap OEM 17's with tires for the winter. That said, my car budget is back in the red for the summer. I'll be able to swing the strut mounts and bearings for the DG spring install but that's about it.
 
XGC75

XGC75

Go Kart Champion
Got a problem today. Crazy overboost at partial throttle, sudden DV actuation coupled with throttle cutting out. Boost leak? Almost feels like when I had the bad MAP sensor in the car.





Here's a video. I never let off the throttle pedal until after the DV actuates in each of these partial-throttle pulls. Not only that but I never get the flutters in ordinary driving.

http://youtu.be/c9XPYmptQcM


The car behaves pretty normally in vacuum, so I can still drive it around if I need to.

Sincerely, XGC75
 
XGC75

XGC75

Go Kart Champion
Wealp, the problem is gone now, all on its own. As is the CEL. Since yesterday evening and all throughout today the car has been behaving okay. The throttle response is still a little jumpy and will modulate while I hold the pedal steady, but the car pulls great and overall the drivability hasn't taken too bad a hit.

I'm not sure if it was just an intermittent connection issue or dying battery (heard of sensor issues elsewhere due to low voltage) or what, but as long as it's not showing symptoms I'm not going to throw money at it.

In the meantime, the new wheels should be here soon :happyanim: Probably going to install them regardless of the 30-40 degree weather coming up. Also ordered Audi TT strut mounts and bearings for the DG spring install. Want to get that all done early April.
 
XGC75

XGC75

Go Kart Champion
Still having intermittent boost issues. http://www.golfmk6.com/forums/showthread.php?t=103815

In related news, I pulled off the DV+ and put the revD back on. I've taken the DV+ for granted. What a difference in throttle response it makes. The turbo spools so much slower without it.

At first when I had the revD back in there I thought the throttle was more predictable. It was almost as though the DV+ messed with the response the tune was expecting, causing some "hunting" or oscillation in torque. By reverting to the revD I got my smoothness back. If only for a moment, though. In just a day the car is back to having rather unpredictable throttle response. Something definitely isn't right.
 
XGC75

XGC75

Go Kart Champion
I think I may have finally figured out the boost issue. My N75 is at 22.3 ohms where it should be between 25 and 35. When I drove with it unplugged the car acted as bad as it ever had when the issue was intermittent. Even saw the boost actual flat line like in the logs when the issue was present. Now that it's plugged back in, though, it pulls stronger than it has in months. So we'll see. As soon as the boost issue comes back with the N75 plugged in I'll pull the trigger on a new one and get it replaced. It's a huge PITA to reach though. Not looking forward to it.

Reinstalled my DV+ while I was under there. Nice to have the quick spool back.

Also fixed my shifter today. It's been getting sloppier and sloppier over the past few months. As it turns out, the bolt keeping the lever on the transmission was so loose it had nearly fallen off. So I tightened it back up and reset the cable alignment (twice - it turns out you can lock yourself out of first if the shifter is too well constrained). Now the shifter has half the play it had before and shifts are nice and snickety - they fall right into place as they should.

Sincerely, XGC75
 
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XGC75

XGC75

Go Kart Champion
Also bought a new set of rims and tires as I mentioned a few posts ago. The rims are 18x8 et35 TSW Interlagos in silver with machined faces. Tires are Falken summer tires.

The tires are pretty great. I'm pleasantly surprised. Coming from the PSS, these are much more active on-center and have better steering feel throughout the turning stroke. They feel fantastic on the highway - subtle inputs correct the line, there's no play in the wheel and yet they're pretty relaxed. They're fairly quiet, too. At least as quiet as the PSS were. One area they don't match the PSS wet traction. I'm not missing that too much, though.

One big problem with these wheels. They were shipped with cardboard placed directly on top of the faces, so they're scratched to hell. It appears the scratches are mostly pretty light on the surface so I hope they can be buffed out okay without losing all the clear and especially without meeting the concentric machined face. Thankfully the seller came through and partially compensated me for the damage after FedEx denied the claim.





There was one wheel with a piece of tape between the cardboard and the wheel and there finish underneath the tape is perfect.





Otherwise they're pretty bad. Most are like this.



They look amazing on the car though.





Sincerely, XGC75
 
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zrickety

zrickety

The Fixer
Wow, never would have thought cardboard would do that.
 
ashchuckton

ashchuckton

Ready to race!
Those look nice on your car. Have you tried to polish those fine scratches out? I'd think you could remove the marks without too much difficulty.
 
zrickety

zrickety

The Fixer
Agreed, they should polish out if they scuffed so easily.
 
XGC75

XGC75

Go Kart Champion
Mother of god, it feels like I'm k04 again. I giggled and blurted "that's fucking nutty!" the first good pull, so you know my car must be running well.

I just finished installing the new N75. The installation wasn't nearly as bad as I thought it would be given the location. The pipes were easy to access and I could actually get an allen into the bolts in the long orientation. I took out all the plumbing with the solenoid but when I took it all off saw it was filled with oil.







After I handled it for a bit, one of the nipples was completely blocked up. Must have shook a half a teaspoon out of there.



The resistance of the two parts was actually the same 23.5 ohms, but the old part dropped continuity intermittently while I was making good contact with the pins. That reflects the kind of behavior I had in the car: okay most days and as if there was nothing plugged in at all on other days. The poor throttle response on the okay days must have been some adaptation that went haywire as a result of the bad days.

Driving impressions:

For a while there the ecu didn't really know what to do. See the video below. It boosted to a random level in the vicinity of where it should but then corrected itself to some other value, corrected itself again, and so on. The video shows it actually finding the right levels towards the end. At full throttle now it goes right where it should.

http://youtu.be/9SGBddSOzSQ



Throttle response at low speeds is much better. Regular acceleration is very smooth. Can't say for sure whether that annoying 2.5k rpm torque bump is still present but there's very little correction required to get a smooth acceleration anymore. Some surging still remains at low throttle in low gears but it only happens when I get back on the throttle quickly so I'm hopeful that irons itself out after a while.

I've got the DV+ in so there's some throttle cut after fast shifts. The difference with the new n75 is that it's tolerable now. The cut doesn't last more than a half a second and boost builds as fast as it should, rather than ramping up slowly between 4 and 6k rpm.

Sincerely, XGC75
 
XGC75

XGC75

Go Kart Champion
As much as the new N75 helped, the car is still not fixed. Still having terrible surging issues and the car shut itself off while coming to a stop. At this point I have plenty of ideas:
  • N75 clogged with oil again
  • N75 is being back-filled with oil from the wastegate
  • Wastegate diaphragm is breached
  • Connection issue at the MAP sensor
  • Connection issue at the ECU
  • Corrupt tune or ECU software
  • Bad ECU
...But I can't test anything to narrow down the problem because the data I extract from APR Mobile is crap. This is just fantastic, 2.5 weeks from a 1200 mile drive to see my buddy (and fellow mk6 GTI owner) in SC.

XGC75 said:
I'm getting a whole lot of crap data from APR mobile. Log for reference (google drive file).

Used the "Fast Boost and Fueling Diagnostics 2" logging set and the results aren't at all what they should be. Throttle Pedal Angle (%) is dead-flat at 0.25 throughout a ~10 minute drive across town. Boost Pressure Specified (mbar) is flat at 180.46875 while Boost Pressure Actual (mbar) varies between 250 and 400 (fortunately it has some relationship to the engine load, just inverse). N75 Duty CYcle (%) will jump all over the place regardless of engine load. Other variables are just as useless.

I'm using the Android Beta with a Galaxy S6. Already shared this to the G+ "APR Mobile Beta for Android" community.

I would love to have a quick fix here because my car is pretty unhealthy and I obviously need some leads to find out what to check next.
Click to expand...
 
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