Overboost and Limp Mode issues

sgg93

Active member
Joined
Dec 11, 2011
Location
Oklahoma
TDI
2012 Passat 6AT, 2012 JSW 6MT
I've got a 17964 code that seems to be causing limp mode under full throttle in fifth. Vac pump tested to 25" hg, everything in the system holds vac EXCEPT the N75 valve, which will slowly lose vac even when isolated. Standard test in Vag Com leads me to believe that the VNT actuator is functioning properly (3/4" movement when called, starts moving at 3-5", stops at 18").

Only thing I noted is that you can definitely hear the turbo as it begins to spool. Doesn't necessarily sound like a leak, but I suppose it could be. You can clearly hear it when accelerating with the windows up. Any way to test it other than plug the intake hose and pressurize it?

Any ideas here?
 

Tdijarhead

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Wife’s car, 2005 Golf TDI Mine, all 5 spds
Is this a 1994 Ford Focus or a 1986 Chevy Silverado?
 

sgg93

Active member
Joined
Dec 11, 2011
Location
Oklahoma
TDI
2012 Passat 6AT, 2012 JSW 6MT
2000 Golf TDI. It broke a timing belt today, so it's gonna be a little bit before I get it back together to troubleshoot this issue. I almost wonder if there was enough stretch in the belt to cause it. We'll see when I get it back together.
 

Seatman

Top Post Dawg
Joined
Apr 23, 2010
Location
Scotland
TDI
2014 Skoda rapid elegance 1.6 cr tdi
Dirty sticking turbo vnt mechanism no doubt, it's the usual cause 99.9% of the time. Could even be the actuator is a bit rusty and sticking things up.
 

Tdijarhead

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Wife’s car, 2005 Golf TDI Mine, all 5 spds
2000 Golf TDI. It broke a timing belt today, so it's gonna be a little bit before I get it back together to troubleshoot this issue. I almost wonder if there was enough stretch in the belt to cause it. We'll see when I get it back together.

Ouch , Frank06 is the member to contact for something like that.
 

sgg93

Active member
Joined
Dec 11, 2011
Location
Oklahoma
TDI
2012 Passat 6AT, 2012 JSW 6MT
Also located a hole in the intercooler while I was pulling the head, could have been a legitimate boost leak.

Picked up a rebuilt head today (came from frank evidently, bought from another member in Central Texas), as well as a turbo oil supply line (twisted mine taking it out), a TB tensioner and an intercooler.

Going to order the TB kit from ID parts, as well as the cylinder head install kit. Any thoughts as to whether an extra 100 bucks is money well spent for ARP studs?
 

pudman2003

Veteran Member
Joined
Feb 17, 2016
Location
Wa
TDI
Mk4 Tropical Orange GTD, Lifted Jetta Wagon TDI, MK2 Jetta Coupe GTD
Don't waste your money on the APR's unless you plan on taking your head off allot.
You can buy many head bolts for the cost of the APR's.
 
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