Moderate boost, low power, no whistle

9755

Veteran Member
Joined
Sep 6, 2017
Location
Burtchville MI
TDI
2001 Jetta tdi
I tried the search button, but it disappears before I can type.

I got this car about a month ago. (2001 Jetta TDI) had zero boost when I got it. Changed all vacuum hoses with oem replacement hoses. That fixed the lack of boost. Then got over boost code. Adjusted the actuator and all was good. Today half way to work I noticed no woosh when I shifted and didn't seem to spool when reved. Then noticed under wot I was only building roughly 10#s of boost and had a ridiculous amount of smoke.

Checked vacuum at the pump while running and maxed out my vacuum tester.
N75 was at 24#s
Egr opened and closed with vacuum
Turbo actuator opened and closed with vacuum

I noticed the black and white check valve flowed both directions...me blowing through it.

Didn't find any boost leaks either.

Also unplugged the maf. Set off cel with no noticable difference in performance.

And the car has straight pipe, rc3 chip, boisi 520 race nozzles

Any direction to go next is greatly appreciated
 

JETaah

Vendor , w/Business number
Joined
Jan 18, 2001
Location
mi 48836
TDI
96 B4V, 1999.5 jettaIV,2005 BEW Beetle
I noticed the black and white check valve flowed both directions...me blowing through it.
That allows vacuum devices like the brake booster to deplete the vacuum reservoir bulb that supplies the N75 valve.
It should not do that. Air should flow from white to black only.
 
Last edited:

9755

Veteran Member
Joined
Sep 6, 2017
Location
Burtchville MI
TDI
2001 Jetta tdi
I'll try connecting the actuator hose directly to the vacuum pump. I did oddly notice the check valve is now only flowing through the white side. I also cleaned the intake and egr about 10k miles ago. The turbo was cleaned with oven cleaner over the weekend. And the actuator moves freely. I'll move the actuator hose tonight and see if that changes anything.
Also I know the link said limp mode. Compared to when I've gotten limp mode, this is different. Before it would loose power around 2500 rpms. It has a steady power currently,builds boost kinda slow,and doesn't pull near what it should. But I'll switch the hose and see what I get. Any other places to check before I start getting new parts?
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
To help with the search woes , here is a user contributed Search Engine.
Every forum search I've ever used has been lacking (but it's all free).
Limp mode, low power, lack of boost are all the same diagnostic tree, as they all have to do with engine management.
Sudden appearance of smoke is troubling, the color of the smoke may help tell you if it's over fueling, oil leakage or coolant ssepage.
 

9755

Veteran Member
Joined
Sep 6, 2017
Location
Burtchville MI
TDI
2001 Jetta tdi
It's definitely over fueling. It's a dense plume of black smoke. But much appreciated for the links!
 

9755

Veteran Member
Joined
Sep 6, 2017
Location
Burtchville MI
TDI
2001 Jetta tdi
Idk how I didn't notice it before...but the vacuum diagram in the link seems different from how mine are routed. I will check that later also. But what's confusing to me about that is how has the car been running great and getting a consistent high 40s mpgs?
 

9755

Veteran Member
Joined
Sep 6, 2017
Location
Burtchville MI
TDI
2001 Jetta tdi
I looked real quick at some pictures on Google on cars. It appears mine is routed correctly. I definitely have my homework to do
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Somen broke, even one of the tiny ass wires lost a bit of section and no longer carries sufficient current. Could be a lot of things. A code reading can often give clues where to look, otherwise start with simple/obvious stuff diagnose each bit for each system.
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
OK, I have to ask: When was the TB last changed?
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
(yes, Timing Belt- there's no throttle-body) You're now good to pursue the performance issues (see my signature).
 

9755

Veteran Member
Joined
Sep 6, 2017
Location
Burtchville MI
TDI
2001 Jetta tdi
Here's what I found. I connected the actuator line directly to the vacuum pump check valve per the link. Everything was back to normal. If I understand right, per the site I have a vacuum leak somewhere?
 

Nevada_TDI

Top Post Dawg
Joined
Aug 17, 2008
Location
Reno, sort of...
TDI
2001 Jetta TDI
Very likely. The solenoids sometimes start to crack and leak vacuum where they are crimped. I don't know if you are still using your EGR, but IMO the only three things that need vacuum on an ALH are: the brakes, the turbo, and the Anti Shudder Valve.
 
Last edited:

9755

Veteran Member
Joined
Sep 6, 2017
Location
Burtchville MI
TDI
2001 Jetta tdi
Egr is currently not hooked up since last night. I'm assuming no I have a boost leak or one of the sensors are leaking. I noticed a high pitched squeal starting around 10# boost
 

9755

Veteran Member
Joined
Sep 6, 2017
Location
Burtchville MI
TDI
2001 Jetta tdi
So I misunderstood the link. I connected the actuator hose directly to the vacuum pump. That gave me boost again. When I should have ran a hose from the pump the n75 vacuum port! Did that and back to not having the power it should. My vacuum check valve seems to be working correctly now. I did notice the vacuum pump metal nipple is a little sloppy. Also noticed there was barely any vacuum at the egr. The vacuum couldn't even hold the hose on my finger. My mighty vac stopped working sometime between last night and tonight. So no accurate numbers to relay to you guys. I'm assuming I'm in the right direction in a leak search. If there are any Michigan guys around, I would definitely appreciate a more knowledgeable mind helping guide the way
 

JETaah

Vendor , w/Business number
Joined
Jan 18, 2001
Location
mi 48836
TDI
96 B4V, 1999.5 jettaIV,2005 BEW Beetle
Assuring that the pump can supply a solid vacuum is essential. A loose vacuum pump nipple can cause problems for sure and easy enough to check. Once you get your MityVac back in action, test the check valve at the small nipple just past the pump. Try to wiggle the pump's nipple and if the vacuum wavers (it most likely will if it is loose) then you have located the first leak in the chain. Move down the line to the next fitting (the Y ) and make sure you have vacuum at the hose, etc...on down to the components. On the N75 (turbo) and N18 (EGR) the vacuum supply is hooked to the smaller nipple. The controlled side of the valve will be the the larger nipple and vacuum can vary there depending on the where the computer is requesting it to be OR not at all if the it is in a limp mode condition.
Also, make sure that the vacuum vent hose (also a larger nipple on the control valves and, in your case, it is on the opposite side of the other two) is open to the air filter box fitting.

It looks like Croswell is about 1 1/2+ hours away from me. I am in Fowlerville, a half hour east of Lansing. My contact info is in my signature.
Another fun place to be on October 14 will be the Grand Rapids GTG. Plenty of free advise will be going on there not to mention cool people. ;)
http://forums.tdiclub.com/showthread.php?t=478971
 

9755

Veteran Member
Joined
Sep 6, 2017
Location
Burtchville MI
TDI
2001 Jetta tdi
Awesome! I will check that stuff over the weekend. If I somehow manage to not have work that weekend, I will definitely make a trip over there. It would be a win win. See some nice cars and meet cool people. As well as see the in laws. That would definitely help persuade the gf to go ��
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagon,2003 Jetta 261K Sold but not forgotten
Check the vacuum at the top fitting of the N75 valve at idle. Use a tee to connect to it.
You need at least 20 inches to fully pull the turbo arm.
Wiggle the fitting that's loose on the vacuum pump, if the 1 way valve is OK you shouldn't loose much there because of the vacuum reservoir ball.
The fitting under the top one goes to the actuator.
Tee into that and start the car.
You should get vacuum, but less the 20 inches. It will drop vacuum when you take off.
The lowest fitting and on the other side goes to the air filter to allow only clean air into the system when running.
Pull that hose off and go for a short ride to see is it helps.
The fitting on the bottom of the air filter has to be clean to let air into the system.
I found WD40 made my car more responsive when I sprayed a bit in the fittings & shook the valve a bit.
I replaced the valve.
 

9755

Veteran Member
Joined
Sep 6, 2017
Location
Burtchville MI
TDI
2001 Jetta tdi
So here's what I got from that. Td into vac on n75 and got 28 for vacuum. Td into actuator line on n75 and holds 19 vacuum. Drive with gauge connected and under wot it holds steady at 10 inches. Still builds boost, has a big hesitation under hard throttle, and has absolutely zero turbo noise. Almost unnoticeable whistle at idle and light throttle, as well as no (whoosh) between shifts. The exhaust is noticably louder than when all was well. Not leak louder. More sounds like a gas 4 cylinder. Am I missing something obvious? Or is the n75 clearly bad when it seems fine to me?
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagon,2003 Jetta 261K Sold but not forgotten
So here's what I got from that. Td into vac on n75 and got 28 for vacuum. Td into actuator line on n75 and holds 19 vacuum. Drive with gauge connected and under wot it holds steady at 10 inches. Still builds boost, has a big hesitation under hard throttle, and has absolutely zero turbo noise. Almost unnoticeable whistle at idle and light throttle, as well as no (whoosh) between shifts. The exhaust is noticably louder than when all was well. Not leak louder. More sounds like a gas 4 cylinder. Am I missing something obvious? Or is the n75 clearly bad when it seems fine to me?
Your 28 inches of vacuum is better then I have.
The 19 & 10 inches sounds close to what I get also, shouldn't be a problem.
On the 'big hesitation under hard throttle' are you saying no power increase or no boost increase?
This might be something with the MAF sensor, though I'm not sure yet.
A log of the boost actual & requested, MAF actual & requested, and N75 (all at once) might show something hanging in the turbo, clogged intake, exhaust, or other possibilities.
There are wizards here that can look at a graph of this and give suggestions.
 

9755

Veteran Member
Joined
Sep 6, 2017
Location
Burtchville MI
TDI
2001 Jetta tdi
It will build boost, but there's a pause. Roughly a second pause before there's power. Car feels relatively normal. But then there's the throttle hesitation, no turbo noise, exhaust note is considerably louder, and lots of black smoke
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
"Black smoke" and "hesitation" - Really is sounding like you've got a crack in one your boost pipes. Sometimes you just cannot see these.

Just make sure you don't have a pool of oil in your IC and, also assuming your turbo isn't heading south, you should be OK to hammer boost. I know that the vanes on my wife's car's turbo had a significant sticky spot in which the RPMs (around 3,200) would flat-line and then, after a pause, jump up: I exercised that car/turbo for what seemed like a year and a half and I am happy to say that there's no longer ANY sign of a lag.
 

9755

Veteran Member
Joined
Sep 6, 2017
Location
Burtchville MI
TDI
2001 Jetta tdi
I found no boost leaks during a pressure test last night. Had the boost tester blow out at 20#. Scared the bajesus outta me! I'll get the intercooler off and the pipes and test them all separately. I'll check and clean out any oil as well and report back. Maybe take a few days unfortunately.

But that also doesn't explain the lack of turbo noise. Forgot to mention...I recorded the actuator at start up. As soon as the car starts, the actuator pulls down to the stop. Is that normal?
 
Last edited:

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
When you have pipes off I'd be looking at that turbo. The hight pitched squeal if not from IC piping can only then be from the turbo. Not sure if you should be looking at the exhaust side as well (others can comment on this), but at the very least gee a look/feel at/of the compressor side.
 
Last edited:

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
That's normal, means actuator works and vanes aren't frozen. Only other thing is adjustment. It should just start to move at 3.5 to 5 "/Hg
 

9755

Veteran Member
Joined
Sep 6, 2017
Location
Burtchville MI
TDI
2001 Jetta tdi
I forgot to say I got the squeal fixed the other day. It was 2 nuts on the exhaust manifold. The were only finger tight. Also did a run with the maf unplugged. I had zero change in performance
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
I forgot to say I got the squeal fixed the other day. It was 2 nuts on the exhaust manifold. The were only finger tight. Also did a run with the maf unplugged. I had zero change in performance
Were these nuts to the downpipe? Why were there loose nuts? Reason I'm asking is that perhaps something else wasn't properly secured, there's been some work done that we're not aware of.

If you had zero change in performance when unplugging the MAF then there's an issue there as unplugging the MAF SHOULD result in a change (should steady-out your engine's behavior, but cut way back on power). And if I'm following this thread correctly (it's very twisty!) it seems as though you CAN get some good boost, boost which I'm thinking that you wouldn't be getting with an unplugged MAF (so this is why I'm scratching my head over your saying that there's no difference with the MAF unplugged- I can only think that you're staying in limp mode, in which case, again, you really shouldn't see higher boost levels).

I see in a previous post you said you could blow through both sides of the vacuum check valve. Was this ever replaced?
 

9755

Veteran Member
Joined
Sep 6, 2017
Location
Burtchville MI
TDI
2001 Jetta tdi
It was nuts on the manifold, not the down pipe. I will hit 18-19#s then hold steady around 13-15. A little low from where it was before. The check valve hasn't been replaced yet. Waiting for it to arrive.

I am not sure what all has been done to the car besides what the owner told me and a list of receipts from parts.

I too am very confused by how it is. It does seem incredibly odd

I'm starting to think the guy I got it from half assed stuff. I had an initial trust in him, as he had nearly a dozen of these cars at his house. I assumed he knew how to repair and maintain these cars. But after a week and replaced all vacuum lines, changed the worst air filter I've ever seen and a boost line that had over 2 feet of slack and melted holes...I'm second guessing his thoughts in this car
 
Last edited:
Top