Slow acceleration, sluggish up hills, boost pressure <6psi. Whats wrong?!

[GirdieAbides]

Hello all,

I have experienced a 70-80% decrease in power in my van. It starts fine (after 3-4 cranks... not great, but normal for mine) and idles fine but is extremely sluggish up hills and refuses to go above ~3000 rmp. I have a boost gauge installed and it is reading a measly 6psi under load, uphill. I have checked the waste gate and actuator, both are fine. The actuator opens at ~12psi. I thought the problem may be a corroded primer pump or a downstream fuel delivery issue, so I tried bypassing all that by sucking out of a diesel jerry right at the injector pump, but had no improvement. I have purchased a cylinder compression tester to check the cylinder compression (273psi is optimal I believe?) to see if one of my cylinders is dead and therefore not contributing exhaust to spool the turbo... but I am doubtful this is the issue. Basically I am out of tricks. Does anyone have any experience with this issue? Any solutions? could it be the injector pump!? I feel like its something turbo related but I don't know what else to check. I'll try anything!

[Growlerbearnz]

Check that the boost compensator on the injection pump is still connected to the turbo. (the turbo has two pressure line nipples- one goes to the wastegate actuator, the other goes to the boost compensator. I'm guessing you have your boost gauge teed into the line that goes to the wastegate actuator)

The compensator diaphragm might also be split- that would suck, but is easy to replace.

Whatever it turns out to be- be sure to write us back and let us know when you get to the bottom of it!

[GirdieAbides]

I have my boost gauge teed into the line going to the IP diaphragm... is that a bad idea? The hose is still connected to the boost compensator, yes. I wish it were that simple.

[Feds]

Could it be a boost leak? I once had a hole in the line to my boost gauge and that caused symptoms similar to what you described.

[Growlerbearnz]

Connecting the boost gauge to the IP line is fine.

Another thought I had- could your exhaust be blocked? Internally collapsed silencer, a new kink where there shouldn't be one, or dirt plugging the tailpipe?

It *could* be a partially seized turbo, but that's unlikely. Still, if you have the driver's seat engine cover out, try removing the rubber air inlet from the turbo and see if the turbine can be easily turned by hand. It shouldn't take any effort to turn it with a finger.

It really does sound like a boost compensator issue. If you can't find any boost leaks like Feds suggested, it might be worth checking that the boost compensator diaphragm isn't split internally. If you take out the four bolts holding the top cover on, the diaphragm is quite easy to see underneath, it's even fairly easy to remove- just be sure to replace it in the same orientation, because rotating it changes how much extra fuel is added under boost.