🌀 Quick Boost Spike Fix on My 930 — Simple Solution
 

Was getting random boost spikes on my ‘86 930 — thought it was the WG spring or overboost switch.
Turned out to be a cracked vacuum line to the wastegate! Replaced it with high-temp silicone hose, and now boost holds steady at 0.8 bar.

Old school fix, but worth checking if you’re chasing boost weirdness.
Anyone else dealt with this?

Just checking that the silicone hose you used is a reinforced type? That hose also required to hold pressure.

Good deal! But to be clear, the hose to the WG is not under vacuum...it's pressure. And the over-boost switch/sensor will not cause an over-boost scenario should if fail. Designed to cut off your fuel pumps in the event of over boosting due to a faulty wastegate (or plumbing to it as you have found).