jackfolstam
Veteran Member
I have an uncontrolled VNT15 on a Mk1 Caddy swapped AHU mtdi and I am seeing about 7psi on the boost gauge. Previously I saw 14psi but I decided to tinker with it and I adjusted the rod to get 18psi. At least once I turned it too far and got 20psi but dialed it in to 18psi. Then, it seemed to be mis adjusted the next day and only had 7psi, and has been that way since regardless of rod length.
Diagnostics:
Pulled vacuum on gauge and reads correct with no leaks. Reality check: engine is low on power. There would normally be turbo lag, then suddenly acceleration, but now it's just, are we going yet?
Reset vnt rod to 3-5inHg.
Pulled all boost and intake hoses and checked for holes and cracks.
Pressure tested the intercooler and hoses together to 15psi and corrected a very minor leak.
Replaced turbo with known working unit (ran it on an etdi swap).
Pulled the glow plugs with a hot engine and found #4 to be wet. Pulled them again today after cruising around and none were wet.
Compression tested with GPs out: 500, 400, 500, 450. I want to check #2 again since the gauge relief valve was leaking badly during 1, 2, and 3 but it's probably true.
EGR was blocked off, tonight removed egr and blocked hole to intake manifold, no change.
Checked cam and crank timing, correct. WIll probably adjust the pump both ways tomorrow to see if ti changes anything.
I also changed out the main seal, crank sprocket that was wallowed, and bolt that was super loose and looked to be reused, but I forget if I messed with the boost or changed the sprocket first.
Can leaky injectors or failing IP cause low boost?
I'm hoping someone stuck a banana up my tailpipe (can't see any foul play) or there's a rag in my intercooler (which I will check tomorrow). Possible cause?
What kind(s) of internal damage can cause this? Cylinder head cracks or bad valve seats?
Diagnostics:
Pulled vacuum on gauge and reads correct with no leaks. Reality check: engine is low on power. There would normally be turbo lag, then suddenly acceleration, but now it's just, are we going yet?
Reset vnt rod to 3-5inHg.
Pulled all boost and intake hoses and checked for holes and cracks.
Pressure tested the intercooler and hoses together to 15psi and corrected a very minor leak.
Replaced turbo with known working unit (ran it on an etdi swap).
Pulled the glow plugs with a hot engine and found #4 to be wet. Pulled them again today after cruising around and none were wet.
Compression tested with GPs out: 500, 400, 500, 450. I want to check #2 again since the gauge relief valve was leaking badly during 1, 2, and 3 but it's probably true.
EGR was blocked off, tonight removed egr and blocked hole to intake manifold, no change.
Checked cam and crank timing, correct. WIll probably adjust the pump both ways tomorrow to see if ti changes anything.
I also changed out the main seal, crank sprocket that was wallowed, and bolt that was super loose and looked to be reused, but I forget if I messed with the boost or changed the sprocket first.
Can leaky injectors or failing IP cause low boost?
I'm hoping someone stuck a banana up my tailpipe (can't see any foul play) or there's a rag in my intercooler (which I will check tomorrow). Possible cause?
What kind(s) of internal damage can cause this? Cylinder head cracks or bad valve seats?
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