Boost builds to 20 and drops to 0

[WOT]

Brother in laws truck (2005 auto) is having a issue with boost going up to 20 and then it dies to 0 and then back to 20. I'm not sure if the wastegate is having an issue or something else (MAP maybe?). It's stock other than gauges.

It sounds very similar to this: https://www.turbodieselregister.com/threads/boost-drops-to-zero.254739/

Anyone else seen this or have ideas on what could be causing it?

Working on getting a video attached...but server seems to taking a long time to process the video so it is accessible in the gallery....

 

[cerberusiam]

Try crimping the boost reference hose with a small pair of vice grips for a test. If that fixes the problem the WG controller is probably bad. You just install a boost elbow in the boost reference hose with the se screw all the way down and the bleed towards the WG actuator. That will limit boost to about 37 psi or so.

 

[AH64ID]

Does it billow black smoke when this happens? Or does it fall on its face?

Even if the controller were bad it should build and hold ~23 psi, unless the controller and WG were bad... but then it shouldn’t build any boost.

Does it have the plastic end capped intercooler?