Hello all,
I'm scratching my head on this one. I noticed a few days ago that the OM603 was a little sluggish and sure enough, I realized that my boost gauge would not go higher than 5psi. I have a manual boost controller and normally I would see 14psi max. I adjusted the manual boost controller to no avail, still only 5 psi. I checked for leaks in the IC plumbing, but could not find any although I hear a lot of air escaping (hissing) which I assume is from the wastegate. I also disconnected the boost controller and ran the wastegate to the turbo pressure port like stock, and still only 5psi

What gives? I could understand possibly a weak actuator spring, but I am surprised that it would have "just gone" weak, as a sprig I would expect the weakening to be progressive rather than sudden.

I also disconnected the manifold pressure switch and again, no change, so I think I can rule out the overboost solenoid as a cause.

I also tested the wastegate with compressed air, and the assembly starts to open at around 10psi, which seems that the actuator spring is within spec.

Ideas? What to check next?
TIA

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)