P1592 rough running suddenly

countrykid

New member
Joined
Dec 3, 2017
Location
usa
TDI
2006 vw jetta
My check engine light came on as I was heading home on the expressway. When I got home I had the code read and there was a turbocharger/supercharger code. After the code was read the car was in limp mode until I turned the car off and turned it back on. The car was fine until I made my next trip with it. The light came in again after being cleared and still ran fine. At the end of my trip I pulled off the freeway and the car suddenly ran horrible. On spool up it jerks and vibrates when trying to accelerate. There is also excess smoke. I have mechanical expierence but am slightly new with the vw. Any hep is appreciated thank you!
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
Limp mode. Next time when it does this, turn the key off and then back on, if it fixes the issue for a few minutes or moments, you are going into limp mode. Limp mode is triggered by over boosting for a period of time (about 5-10 seconds). This is the most common issue. its usually caused by a bad vac (boost) line to something that causes the waste gate actuator to not work properly when commanded.
Common issues and the fix for them.

Vacuum lines or boost lines: Inspect or replace them all. usually 3mm, 4mm and 5mm hoses. dont use cheep ones, get quality silicone or VW braided lines from IDparts.com or where ever. Not sure about your ECU but on MK3's there is a boost line going into the ecu and inside the ecu to the MAP sensor and it needs replacing too, if you have one.

N75 Valve: you should have a slight clicking from it, kinda like a CCV valve. some times you can clean them, they are not very cheep ($75) for an OEM. usually replacing it is best.

MAF: this is the sensor on the intake air duct right after the filter. ONLY CLEAN WITH MAF cleaner. A cold air intake usually is the culprit for killing them. Check out this link to understand why. Disconnect it and if driving conditions do not improve then its bad. (only after you make sure you have no boost leaks and all your lines are perfect shape.) http://forums.tdiclub.com/showthread.php?t=290373

Boost leaks: Check all your pipes after the turbo to and from the intercooler and to the intake manifold. take them apart, and put back together to make sure no cracks etc. inspect the intercooler too. You will see some oil on the pipes. Its normal. Just wire off the parts your connecting with a light amount of brake clean on a rag. DO NOT spray it into or on the pipe. it could cause a temporary runaway. Happend to me lol, i was lucky, kinda.


thats about it. Fix and inspect those items. in that order one at a time with test drive in between to make sure you dont jsut thorw parts at it.

From what you described, Vac lines, turbo actuator, and you have a boost leak, BAD too, your IC pipes and boots, check them
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Sudden rough running sometimes occurs when one of the big pipes get loose, usually its underneath.
 

countrykid

New member
Joined
Dec 3, 2017
Location
usa
TDI
2006 vw jetta
Is there a way to pressure test the system for boost leaks? Initially when the engine light came on and the car went into limp mode I was able to turn it off and restart it causing the limp mode to go away. Now the problem is steady but is not limp mode. I inspected the intercooler hoses and connections and they appear to be fine.
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
There's no substitute for some sort of data reporting device. Running an Ultragauge/Scangauge or VCDS can really help pinpoint issues. Lots of times when not under pressure (load) -which is when you're looking- loose connections/holes etc won't be visible. But, that said, I wouldn't jump to conclusions that this is necessarily a boost issue (probability says yes, but w/o actual data you're only going to be guessing).
 

countrykid

New member
Joined
Dec 3, 2017
Location
usa
TDI
2006 vw jetta
Last night the car actually started running better and had full power (more boost) for a brief period. After getting the codes read again they shop failed to mention another code P0102 which is MAF. Cleaned the sensor with MAF cleaner and reassembled. The problem still exists but gave me a further clue. The boost sort of comes and goes now and then, also if the car is running with no boost and I restart it, it becomes slightly better. Could this be the n75? If so the only way I can find one is online, is there a substitute valve or method for temporary use?
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Check the N75 wiring is good. The device itself simply adjusts vacuum flow, so no, the N75 wouldn't do that. There is a vacuum line runs to the air box sometimes gets left off, doesn't usually affect much.
Have you seen this? From Ross Tech wiki, great resource.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Does the engine start and idle OK? Sound normal? Not missing or making a loud "bump-bump-bump" sound?

The VNT actuator is easy to check. You can get to the vacuum line up top on the BRMs. Pull it off and stick a small vacuum hose down on it attached to a hand held pump, or in a pinch, your mouth. Suck on it, the rod should move up and stay put (yeah, I just typed that, stop laughing you pervs... :p ).

A smoke machine works great to find small boost leaks. The big ones are easier to find.
 

countrykid

New member
Joined
Dec 3, 2017
Location
usa
TDI
2006 vw jetta
The car starts good and idles good as well. When this happened I was driving the car steady for hours and then lost power when I pulled off the expressway. Currently power goes up and down and car is very smokey.
 
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