My RS7 started to act up about six months ago with intermittent and seemingly unrelated issues (2017, 142,000km, V8, twin turbos, variety of mods, daily driver).
Audi Hamilton (great folks, shout out to them for all their work and research) did a deep dive and double checked the ECU program. Nothing askew. Car ran well for about 3 hours, then back to old habits.
So, I had a go. Replaced plugs, air filters, ignition coils. Serviced the O2 sensors. Checked fuel pressure, at idle and under load. All good. Ran well for a half a day and then, ah, not so well.
Several trips into Audi Hamilton, many emails with technician and others, too many evenings in my garage changing and testing parts. The issue was severe enough that it was disrupting use as my daily driver. Following another unhappy drive and grasping at straws, I got home and popped the engine cover off - thinking maybe MAF module or fuel pressure.
The engine cover has a foam-backed aluminum heat shield to insulate the decorative plastic top (the cover also helps route fresh air over the turbos). The aluminum shielding seemed to have been rubbing against the bank 1 turbo gate valve actuating rod. I finished poking around at other things, cleaned the engine cover, and put it back on, not thinking much of it.
Off with Deb for a coffee and same old same old. Grrrr. Then one of those Eureka moments – was the actuating rod was catching on the heat shield? Stop. Off comes the engine cover. Drive. And, no backfires, no stumbling, no rough idle. Spirited drive home!
At home, I could see the gate valve arm was getting caught (not just rubbing) on the heat shield. Some of the glue tabs holding the heat shield had broken free, delaminating it from the cover. As the engine got hot, the foam softened and would sag allowing the aluminum to contact the actuator. Four of the eight adhesive tabs had broken free. Drove for a few days without the engine cover – no problems. Replaced the engine cover, problem returned, following the newly understood schedule.
So, I “repaired” the engine cover:
Car is happy, I’m happy, and Deb’s happy. Audi has something to watch for with other cars. And now you know too.