B5.5 MY05 2.0 TDi P0299, P0101

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis (where it's safe)
TDI
There are just too many to list....
You said you found a hole in the S-shaped hose and replaced it... and that worked for a bit. I suspect it just found the next weakest link in the chain.

Take the remaining 3 rubber hoses off the car and carefully look them over, and carefully look at the intercooler for any cracks or splits. You may have to take the bumper cover off to properly see it (easy).
 

MOGolf

Top Post Dawg
Joined
Jun 27, 2001
Location
underneath something
TDI
2001 Golf GLS TDI Reflex silver, rough road suspension and steel skid plate, 2004 Passat Variant, Candy White, rough road suspension and geared balanced shaft module, and much, much more. 2016 LR RR HSE TD6, 2019 Jaguar I-PACE
Other things:
- Mass Air Flow sensor (P0101 code)
- hole in the intake tube from MAF to turbo
- Faulty pressure sensor (giving bad readings)
- Faulty EGR valve (not operating properly and thus impacting air flow)
- small hole rusted through the cross-over tube
- at 393K miles, the vane operating ring inside the turbo may be worn and it truly is not making boost adequately all the time but can some of the time.

Since you have VCDS, use the generic OBD II interface and capture/post the freeze frame data from the fault.
 

VariantB3_VR6

Well-known member
Joined
Aug 25, 2004
Location
Winchester, VA
TDI
05 B5-A, 01 A4-M
I haven't gotten the 0101 since I cleaned the MAF. the VNT lever seems to move just fine, with no real catching.. The EGT looks/sounds to function fine during testing via VCDS. I'm going to get under it again, and look closer at the IC piping and the MAP (I think that's where it resides, as well). Like I said, I've smoke tested and low-pressure tested, and get no signs of a hole, leak, or failure.
I can say, however, that the vacuum pump's nipple (that connects to the hard plastic line) does wiggle a little bit, like it's loose.
I might see if I can "temp fix it" to determine if that's a problem, as well.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis (where it's safe)
TDI
There are just too many to list....
The VNT Basic Settings test will show you inside of 20 seconds if there is enough vacuum to operate the turbocharger. And on the BHW, you do not even need to get under the car, it is right there easy to see from the top. It will just tell the ECU to duty cycle the N75 ON/OFF/ON/OFF, with the engine at idle, and you can watch the actuator go UP/DOWN/UP/DOWN. If it does this, you have verified the control side is good and working.
 

VariantB3_VR6

Well-known member
Joined
Aug 25, 2004
Location
Winchester, VA
TDI
05 B5-A, 01 A4-M
So fixed a small leak in the intake hose (btwn turbo/MAF). No other leaks found anywhere. Test-drove the car again, this time with the EGR disco'd. From cold, to operating temp, no limp mode. Once it reached op temp, it started limp moding. It's really weird, as the 'actual' would follow 'specified', then after it was full temp (90-95c), Actual would follow specified, then slowly taper off, until LIMP was activated.

I guess my last option, now, is to pull this turbo off and inspect and/or rebuild it.. I'm at a loss.. I just struggle with the thought of the turbo being the culprit, since it works fine, up until Op temp, or shortly after, then starts to trip limp mode and 0299..
 

thundershorts

Top Post Dawg
Joined
Jul 15, 2010
Location
west chester pa
TDI
2015 passat tdi sel premium 2015 golf s tdi gls tdi b5.5, 2002 eurovan,Peugeot 505 td,Citroen cx25 prestige
I had similar problem it was n75. If you had changed it, was it replaced with new om one?
 

VariantB3_VR6

Well-known member
Joined
Aug 25, 2004
Location
Winchester, VA
TDI
05 B5-A, 01 A4-M
I had similar problem it was n75. If you had changed it, was it replaced with new om one?
I did replace it, not with an OEM, but the exact issue remains. It vacuum tests functionality as intended. I replaced the OEM one as a guess, not because it was actually bad. Thank you for the suggestion, for sure, though.

After lengthy discussions with some friends, it definitely seems to be more "electronic" related, rather than hardware-relate, since when it goes into limp, I can cycle the ignition and it clears up for a brief period. Starting to wonder maybe the MAP? I really need to find a boost gauge and watch the boost gauge to see what's actually going on, from a mechanical reading, rather than an electronic reading.

I'm so baffled.
 

zzdiesel

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Joined
Dec 10, 2010
Location
sask. mostly now Wa.
TDI
05 passat tdi Geared BSM and Bewcam 2nd 2005 deleted ,converted and bew cam stage 2 Malone3 tune.
Any chance of back pressure in the exaust system? Some restriction?
 

thundershorts

Top Post Dawg
Joined
Jul 15, 2010
Location
west chester pa
TDI
2015 passat tdi sel premium 2015 golf s tdi gls tdi b5.5, 2002 eurovan,Peugeot 505 td,Citroen cx25 prestige
Charge hoses are quite stiff and splits can be hard to see and open up when under fairly high pressure. You might try removing paper air filter for testing, also have you run it with maf unplugged?
 

VariantB3_VR6

Well-known member
Joined
Aug 25, 2004
Location
Winchester, VA
TDI
05 B5-A, 01 A4-M
Any chance of back pressure in the exaust system? Some restriction?
I'm sure there's a chance, but I'm not sure how I'd check that..

Charge hoses are quite stiff and splits can be hard to see and open up when under fairly high pressure. You might try removing paper air filter for testing, also have you run it with maf unplugged?
I have NOT tried without the MAF connected.. I HAVE tried without the paper air filter. made no changes..

What does unplugging the MAF do, or will it even drive w/o it plugged in?
 

zzdiesel

Veteran Member
Joined
Dec 10, 2010
Location
sask. mostly now Wa.
TDI
05 passat tdi Geared BSM and Bewcam 2nd 2005 deleted ,converted and bew cam stage 2 Malone3 tune.
I don't see how the turbo, in and of itself can make pressure, then not. If you have confidence that the control side is good, and that the pressure side is good, then possibly the exaust side is not and cutting the exaust flow through the turbo. Backpressure could build up with a partially blocked exaust.

I have a Mercedes 450 sl that was lacking power. Suspecting the cat was bad I drilled I believe a 1/2 in. hole in the exaust pipe before the cat. It made a huge differance in the power. Away went the cat.

Have you taken the bumper cover off and really inspected the intercooler as OH suggested?

On another forum, not VW, a guy with a similar problem finally found a hose on the pressure side that the inner lining had come loose and would periodically block the flow. I have no idea if that is possible on our cars.
 

VariantB3_VR6

Well-known member
Joined
Aug 25, 2004
Location
Winchester, VA
TDI
05 B5-A, 01 A4-M
I've checked all the hoses, at this point. I agree on the 'not being the turbo', as well as not being the exhaust.. as if it were mechanical issue, it wouldn't be temp-related (seemingly) and definitely not reset-able via a key cycle.

Again, how/what would one test by disconnecting the MAF?
 

auntulna

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Joined
Mar 13, 2005
Location
Springfield, MO
TDI
05 GLS Passat wagon, mit panzer plate
The car will run with the MAF unplugged. The computer uses default values instead of actual. If the car runs better with it unplugged, then the MAF is bad. If no difference, MAF is not the problem.
 

VariantB3_VR6

Well-known member
Joined
Aug 25, 2004
Location
Winchester, VA
TDI
05 B5-A, 01 A4-M
The SAGA continues...
The MAF graphing looked fine. I tried unplugging it, and it went into limp mode pretty quickly under acceleration. After that, I could NOT get the MAF to graph anymore.. Idling, the MAF was saying 280g/s requested, 400 actual. Under heavy load, they'd look about the same-ish..

As for disconnecting the actuator from the VNT, I'd have to be a damned magician to do that with it still on the car.. My fat meat hooks will never fit.
I T'd a vacuum gauge into the Actuator's signal line. light cruise, it's around 20-22in, and when it shifts, it'll dip to about 5, then work it's way back up. I don't know what I'm looking at/for, but that's what it's doing.

I'm guessing, at this point, it turbo-removal time.. IDK what else to do. ALL boost hoses, intercooler, vacuum lines, etc, have been checked or replaced. N75 replaced.
I don't know what I'm in for, but will do it anyway. The scary part of it all is that oil feed line; it looks like crap.. rusty/crusty fitting. I sprayed some Kroil on it, and will do it again, and MAYBE sunday, I'll start that venture.. I'm gonna lose my sh!t if I get it removed and it's fine. LOL If you guys got any suggestions, I'm all ears.
 
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