Suddenly stopped making boost.. whats next?

AgentE

Well-known member
Joined
Jul 15, 2013
Location
Los Angeles
TDI
MK6 Jetta
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

Well-known member
Joined
Jul 15, 2013
Location
Los Angeles
TDI
MK6 Jetta
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

Well-known member
Joined
Jul 15, 2013
Location
Los Angeles
TDI
MK6 Jetta
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.
 

Dannyboy

Veteran Member
Joined
May 25, 2013
Location
Mb
TDI
2014
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.
 

AgentE

Well-known member
Joined
Jul 15, 2013
Location
Los Angeles
TDI
MK6 Jetta
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

Well-known member
Joined
Jul 15, 2013
Location
Los Angeles
TDI
MK6 Jetta
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.
 

Dannyboy

Veteran Member
Joined
May 25, 2013
Location
Mb
TDI
2014
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.
Sorry didn't register the 98 part, my bad.
 

AgentE

Well-known member
Joined
Jul 15, 2013
Location
Los Angeles
TDI
MK6 Jetta
Post #4 Old Chap ;)(y)
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

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Daughters car, 2005 Golf TDI Mine, all 5 spds
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.

 

AgentE

Well-known member
Joined
Jul 15, 2013
Location
Los Angeles
TDI
MK6 Jetta
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.

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.
 
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