Strange turbo problems on way to work this morning. How to trouble shoot?

hutchman

Veteran Member
Joined
Sep 6, 2005
Location
Virginia
TDI
2006 Jetta TDI Pkg 1, 5 Spd, Graphite Blue / 2002 Jetta GLS, Black w/tan leather
On the way to work this morning, my 2002 MK-Iv(A4) was acting strange. I noticed that the boot was way high even though I wasn't romping on it. Then I felt a slight surge and the boost dropped to next to nothing ... maybe 5-6 psi tops ... and not much power.

Could it be my actuator or vanes getting stuck open or close? About a year ago I took the actuator linkage loose so I could work it to feel how smooth it was. I did feel a slight hesitation at one point.

I have a mitty vac so I can try to work the actuator and see what happens or take it loose and work it by hand and see how that feels.

I know to check to make sure the actuator is holding vacuum.

Beyond what I've already stated, I don't know what else to check to trouble shoot the problem.

Turbo is a VNT-15. I doubt it has anything to do withthe intake as I have a DGRP and it gets run up to 4500RPM at least once a day and I normally shift above 3k when warm.

Thanks!

Brian
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Sounds like a sticking VNT to me if it overboosted. Put your vacuum pump directly on the VNT actuator and pump it up, then release. It should snap back to the stop easily and immediately.
 

hutchman

Veteran Member
Joined
Sep 6, 2005
Location
Virginia
TDI
2006 Jetta TDI Pkg 1, 5 Spd, Graphite Blue / 2002 Jetta GLS, Black w/tan leather
Thanks oilhammer! That is what I thought too but I thought I would consult the wisdom of the club.

I would kind of like to tear it down and clean/rebuild it just for preventive maint. It has 115k on it (69k by someone else).

The car has RC3+ so it could use a better turbo (which is why I have the boost valve) and I don't get too crazy with it.

I'll work on it when I get it back home and let everyone know what I find.
 
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