Suddenly stopped making boost.. whats next?

[AgentE]

98 beetle AGR

I was enjoying a drive and suddenly lost power. Got home and looked some things over.

All vacuums are intact and attached. (all lines were replaced with silicone lines about 4 months ago)

The computer is commanding/specified boost pressure but I get nothing over 1030 bar despite the ecu expectation.

In this chart, Yellow is actual boost pressure, Green is Specified, Red is Engine Speed Grey is charge control duty cycle:

In this chart you can see the ecu is expecting boost that literally never comes.

What could possibly be amiss here? stuck wastegate?

 

[AgentE]

I was only able to move the wastegate lever about 2mm by hand and was very crunchy and gritty. I guess I need to test the n75, apparently if there is no vacuum, there be no boost.

 

[AgentE]

I swapped the egr and boost control pressure converter valves and got some boost. But its surging and bucking and even made a bad noise upon heavy load.

 

[AgentE]

I'd say your vnt ring has carbon/rust causing sticking vanes.

My son's BRM has this problem occasionally during winter. Working the actuator arm until it moves freely is one way. I use a long flat screwdriver. A can of oven cleaner in the turbine side is another but it's messy.

Thanks for the reply.

I've got a wastegate turbo. But tomorrow in the morning I'm going to test the whole vacuum system including the valves and turbo actuator. I'm going to see if the actuator hold vacuum and moves the actuator lever the full range.

 

[AgentE]

Performed testing on the entire vacuum system using a guage and vacuum pump. It held 20in throughout the system.

When vcds cycled the n75 it functioned perfectly and held the same amount of vacuum as the system when switched on.

When I applied vacuum to the wastegate actuator it moved the lever, like 2mm. It is stuck in the open position. When vacuum is removed the wastegate actuator does not retract into the closed position.

I removed the downpipe and there is a lot of soot and debris in the exhaust housing but I could not see or access the wastegate.

 

[AgentE]

Sorry didn't register the 98 part, my bad.

No worries.

Literally everyone I am emailing, darksidedev, ecstuning, etc all take my VIN and then try and sell me an ALH turbo with vanes. This is crazy.

 

[AgentE]

Sorry didn't register the 98 part, my bad.

The plot thickens..

The car has a VNT15 038253019a installed now. I dont know what to make of this yet.

 

[AgentE]

Well if it has a VNT 15 in there I'd know what I'd be looking at....

Do tell sir?

Im looking at a VNT17 but am considering a hybrid like a 15/17. What are the pro and cons? I hear the 17 takes along time to spool and the hybrid has heat issues?

 

[AgentE]

Post #4 Old Chap

Ahh right.

When I tested the actuator I spent an hour or two trying to free the arm. I used vacuum and some other techniques to try and free it up but it's stuck pretty good. I would love to fix it for that cheap, not excited to spend $800.

When you referenced the oven cleaner, are you referring to removing the turbo and disassembling it and cleaning it up with the oven cleaner?

 

[Tdijarhead]

Take the turbo off separate the assembly and clean it, no need to spend $800 on a new turbo. You will not need oven cleaner if you disassemble the turbo carb or brake cleaner and elbow grease will work much better.

VNT Repair Procedure

If you have a turbo that is jammed up and causing an Overboost code, you will need to follow the following procedure. To keep the file size to a minimum, I eliminated the removal process and kept it to strictly the repair of the turbo. This issue is often caused by "Babying" the motor and...

forums.tdiclub.com

 

[AgentE]

Take the turbo off separate the assembly and clean it, no need to spend $800 on a new turbo. You will not need oven cleaner if you disassemble the turbo carb or brake cleaner and elbow grease will work much better.

VNT Repair Procedure

If you have a turbo that is jammed up and causing an Overboost code, you will need to follow the following procedure. To keep the file size to a minimum, I eliminated the removal process and kept it to strictly the repair of the turbo. This issue is often caused by "Babying" the motor and...

forums.tdiclub.com

Cool, I appreciate the response.

Do you have any opinions on the 15/17 hybrid turbo from xman? I went with the regular vnt15 - My turbo has 180k miles on it.