Just a maintenance update:
After 15k or so running EBC GreenStuff pads they didn't have much pad material left and my front discs were warped, so new front discs and new pads all around. I liked my GreenStuff pads, they held up to a lot abuse, but still faded in hard hoons - although considerably better than my friends' stock pads. I decided to go for YellowStuff pads this time.
The brake feel is so much better (much firmer and progressive pedal) and brake bite is insane compered to my worn pads, even when they're cold, when they're warm, my ABS/tyres can barely keep up and the wheels do lock up more easily than before.
I ended up biting the bullet and getting my 108s refurbed again. After 20k miles or so the rears were full of stone chips and plenty of small scars on the lips from removing the tyres (3 sets of rears, 2 fronts). I love the silver wheel look on blue cars, so wanted to go for the same, but to make it more special, I asked for Hyper Silver to make the curves of the 108s more obvious. The photos don't give the look justice!

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Lately I've come across a few rough running issues. The first one being a hesitation between 2-3k revs when the engine was cold, but once up to temps, if I turned the engine on and off again, issue completely went away. I tracked that down to one of the coils - so I replaced all 6 for good measure. I must say, if didn't have another Z4 a home to swap bits back and forth, this would have been a hard one to track - no errors, not really a misfire, values on INPA were completely within parameters. Just weird.
Then a couple of weeks ago, I started feeling like the power wasn't very linear - some weird spikes in power. Especially around 3-4k revs. And throttle response either a bit too hesitant or too keen and car was a bit jumpy, and sometimes the idle would be all over the place, cold start would shoot up to 2.5krpm randomly. Again, no errors, INPA values all fine, tried adaptations many times, no luck... Started by removing VANOS solenoids, cleaned and tested them, installed them again and problem still persisted. So bought a borescope and went down the intake to check the small DISA. Both DISAs proved to be working perfectly - I even recorded DISA #2 operating.
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At this point I was disappointed, as the only other thing left to test was the eccentric shaft sensor. Not easy to get to, and no shortcuts to check it, so would be a matter of just replacing it (+ all the gaskets and bolts). Put DISA #1 and the intake back together, and surprise, surprise the issue is gone. As I took the intake pipes apart, I made sure they were in place and tight, and all seemed to be, but now I can only imagine they weren't and a a small vacuum leak was causing the issues I experienced. Or it's a coincidence and the problem will come back again. But 200 miles later and all seems fine, so we shall see.
Bonus: checked all of my intake valves. Advantages of port injection and good fuel, no carbon build up!
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