Yep - stepping back from the problem it is definitely the symptoms of a vacuum leak.



I'm gonna take it apart again tomorrow and check the ISCV especially. The surging in idle seems to me that it can only be cause by a vacuum leak DOWNSTREAM of the ISCV and throttle body. Upstream it's just getting unmetered air (throwing off the AFR but correctable with O2 feedback), but downstream it's both unmetered and unrestricted. I'm pretty sure I got it all back together right but there being no hose clamp around the ISCV on the downstream side, and the general impossibility of seeing any of that area, means I could have missed it.



To cool off I removed the extremely dark tint from one of my new E70's windows. It's so dark you can hardly see out of it at night. And I fixed my lawnmower. So I didn't get nothing done today.

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2003 3.0 5MT Topasblau
Purchased in 2016 and sold in 2024
2012 35d Platingrau