Old Turbo Not Working, New Turbo Not Working

bioTDI

Well-known member
Joined
Apr 24, 2003
Location
Tempe AZ USA
TDI
1996 Emerald Green Passat
I've read up on the common problems around the VNT15 turbo. My old one was gunked up and the lever wasn't moving by hand, so I had my mechanic clean it and it worked great for about 6 months, then it stopped working again, same problem. I had him replace it last week with a remanufactured VNT15 and now that one's not working. He pulled vacuum manually on the actuator while driving and nothing. When he pulls vacuum, the lever moves, but no boost. The lever moves as it should when the engine is started, it moves when pushed on manually or under accelleration (ie under its own vacuum), but it's not boosting.

I asked him to double check the intercooler pipes and everything and he says they are all connected. I have no idea where to go from here, what else to test, and I've spent almost $2000 on turbo bills in the last 6 months. I've never had this many problems with any other car, and I've been driving VWs and other diesels my whole life.
 

Nitrowolf

Veteran Member
Joined
Sep 22, 2005
Location
Kansas City
TDI
White 2003 Jetta TDI
When you say no boost, do you mean it's literally generating no boost, or you just don't feel any boost/the car doesn't go faster kinda thing? If you literally mean no boost, how are you measuring that?

I don't suppose you have a boost gauge installed?

There are several places that the boost piping can be compromised, either through old/cracked/corrupted/busticated hoses, or something, such as a rag, could be blocking up the intercooler. There are many stories of people accidentally leaving a rag inside the intercooler after cleaning it, thus clogging it up.

I'm assuming otherwise, the car is running fine. That being said, if the turbo is in operating condition and the car is running fine, something is either blocking air to or from the turbo, or there's a leak somewhere. That is literally the only two things it could be, assuming the first two premises are true.

I would follow and inspect each segment of the piping to the turbo and then from the turbo into the intake manifold checking for cracks/leaks or some blockage.
 

chrisfiat

Veteran Member
Joined
Jul 14, 2006
Location
farmington nh
TDI
97 jetta
check for a pluged exhaust especaily if you have had oil in the intake or turbo problems before. a quick check is to loosen the turbo outlet pipe and doa quick road test for boost if it does start removing the system and checking for a pluged cat or muffiler
 

alphaseinor

TDI Innovator, Gone but Not Forgotten
Joined
Jul 30, 2006
Location
Denton, TX
TDI
'03 Jetta TDI 780,000 miles (totaled out), 01 Audi TT 225 Quattro 230,000 Miles (runs great!), 00 Cabreetle Beetle dash, ALH & MK4 harness Swap
IIRC... opening the turbo more doesn't mean more boost, not all the time at least, there is a specific amount of "bite" needed on the turbine to prevent cavitation.


I would check to see if you have vacuum at the vacuum pump, and swap your n75 valve with the one to the EGR
 

bioTDI

Well-known member
Joined
Apr 24, 2003
Location
Tempe AZ USA
TDI
1996 Emerald Green Passat
turbo

I have a hunch it's not the turbo either. By no boost I meant no power and the MAP reading on my Scangauge stayed at atmospheric pressure (~14) when it used to go up to 27 or so under accelleration.

So just disconnect all the vacuum lines from the EGR solenoid and plug all the lines from the N75 into it?
 

bioTDI

Well-known member
Joined
Apr 24, 2003
Location
Tempe AZ USA
TDI
1996 Emerald Green Passat
Stealership Story

The old turbo is definitely gunked up - actuator arm barely moves at all. The new turbo has full travel.

I took it to the Stealer as a last resort Monday night. First they said it needed a new EGR valve, then a few days later new vacuum lines through the firewall, then a new MAF sensor, and today they say I need a new injection pump because the temperature sensor inside is bad and the ECU is reading -5'C. So if they had their way I'd replace everything part by part because they don't know what is going on and maybe someday it will work. I'm already out $1300 with the reman turbo and now they say I need a new IP for an additional $1600 on top of the $250 I owe them for "diagnostics."

I asked the "Service Advisor" how it could be possible that the turbo, MAF, EGR, vacuum lines, and fuel pump could all coincidentally fail at the same time and he suggested I sell the car.
 

alphaseinor

TDI Innovator, Gone but Not Forgotten
Joined
Jul 30, 2006
Location
Denton, TX
TDI
'03 Jetta TDI 780,000 miles (totaled out), 01 Audi TT 225 Quattro 230,000 Miles (runs great!), 00 Cabreetle Beetle dash, ALH & MK4 harness Swap
You should run away from the dealer NOW!!!

read my sig... why I think dealers suck, and performance problems.

Vacuum lines are $20 Razor blades are like... what... $1??? 2 hours of labor to replace... I can train a monkey to do them.

The temperature sensor in the injection pump is replaceable, but the dealer WON'T DO IT!!!

I would suspect the MAP sensor on the intercooler (or boost piping like mine), especially since it always shows 1 bar. If there was no boost it would go into a vacuum (.5 bar at the minimum). If not there is something screwy with the electrical system to the N75... can you actuate it with the VAG-COM and see if it clicks?

are you sure the MAP is plugged in?
 

bioTDI

Well-known member
Joined
Apr 24, 2003
Location
Tempe AZ USA
TDI
1996 Emerald Green Passat
chrisfiat was right!

Thanks for all your help. Turns out it was the cat. Derek and the guys at Exklusiv here in Phx went the extra mile to fix it. They recreate the series of events as such: fuel temp sensor went out, causing too much fuel to the cylinders, soot clogged cat, exhaust restriction took out turbo. Makes sense to me.

Runs great now!

So now the car has a reman turbo (12 month warranty), used IP (12 month/12k mile warranty), new cat (12 month), new fuel filter, new tires (unrelated) and newer timing belt, rollers, tensioner, water pump, etc. (20k miles ago). Oil and filter just changed (Mobil 1 Truck/SUV).

IT WILL SOON BE FOR SALE since my wife got sick of not having a running car for 6 months and bought a gasser.

2001 Black Jetta GLS TDI, auto, 10-disc changer, Premium (pre-monsoon) stereo, tan leather, moonroof, steering wheel radio controls, etc. 116,000 miles, Mobile 1 Truck/SUV and B100.
 

Drivbiwire

Zehntes Jahr der Veteran
Joined
Oct 13, 1998
Location
Boise, Idaho
TDI
2013 Passat TDI, Newmar Ventana 8.3L ISC 3945, 2016 E250 BT, 2000 Jetta TDI
All that B100 probably gunked up the catalyst.... I can't wait for the new DPF's and folks trying to run the old generation bio fuels instead of Bio-GTL renewable super fuels (of course those aren't sold here....YET!) :D

DB
 
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