B5.5 MY05 2.0 TDi P0299, P0101

oilhammer

Certified Volkswagen Nut & Vendor
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Dec 11, 2001
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outside St Louis, MO
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

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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

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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
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Location
outside St Louis, MO
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

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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

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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

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Aug 25, 2004
Location
Winchester, VA
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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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Dec 10, 2010
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sask. mostly now Wa.
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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

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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

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Winchester, VA
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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

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sask. mostly now Wa.
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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

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Winchester, VA
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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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Mar 13, 2005
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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

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Aug 25, 2004
Location
Winchester, VA
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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.
 

VariantB3_VR6

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Aug 25, 2004
Location
Winchester, VA
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05 B5-A, 01 A4-M
Removing this Turbo (yeah, as you can see, this isn't my daily driver now, as I've not touched it since like November).. I've got everything loose, minus one turbo manifold nut: The one by the EGR tube..
Is there a trick that I'm just missing? I cant get a wrench on it, and obviously cant get a socket on it with the EGR Cooler still in place. Tried to remove the cooler, but I need to remove the WGA to get the last bolt out.. Cant remove the WGA because I cant get to the engine-side 10mm WGA bracket bolt.. lol
Any suggestions/tips to get these two fasteners?
- The WGA inner bolt is being denied by a stop screw, of sorts, on the turbo.
- The Turbo manifold nut just has no room to get a tool in there (socket, nor wrench)..

Thanks!
 

VariantB3_VR6

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Winchester, VA
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05 B5-A, 01 A4-M
HOLY crap on a cracker, was that front turbo nut hard to get out!!
and the turbo looks fine, moves fine.. it was a little 'sticky' to the forward end of the ring movement, but didn't take much effort to overcome.. I'll get some sooty pics later; it got too hot to continue working in the sun.
 

VariantB3_VR6

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Aug 25, 2004
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Winchester, VA
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05 B5-A, 01 A4-M
@oilhammer , I've misplaced the two bolts that holds the WGA to the turbo. Do you happen to know what size these bolts are, thread-pitch/diameter-wise? I'm trying to find replacements, or something that will work, at the very least..
I've completely cleaned up the turbo, and reassembled the CHRA back into the compressor/turbine housings. the VNT arm no operates so smoothly, that I took it back apart twice, thinking I'd not got things lined up.. :)
I want to reinstall it all and see what happens. I hate to give up on the ol' 400,000 mile girl..

If this doesn't fix it, then I'm at a loss, as I've replaced the BCS, all vacuum lines, and super-cleaned the turbo.
 

Mozambiquer

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@oilhammer , I've misplaced the two bolts that holds the WGA to the turbo. Do you happen to know what size these bolts are, thread-pitch/diameter-wise? I'm trying to find replacements, or something that will work, at the very least..
I've completely cleaned up the turbo, and reassembled the CHRA back into the compressor/turbine housings. the VNT arm no operates so smoothly, that I took it back apart twice, thinking I'd not got things lined up.. :)
I want to reinstall it all and see what happens. I hate to give up on the ol' 400,000 mile girl..

If this doesn't fix it, then I'm at a loss, as I've replaced the BCS, all vacuum lines, and super-cleaned the turbo.
Have you by any chance removed the valve cover to look at the camshaft? I didn't see that in any of your posts. That's another thing that can cause both of those issues, the p0101 because it's fluctuating so much and the p0299 because it can't get enough boost.
 

VariantB3_VR6

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Location
Winchester, VA
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05 B5-A, 01 A4-M
Have you by any chance removed the valve cover to look at the camshaft? I didn't see that in any of your posts. That's another thing that can cause both of those issues, the p0101 because it's fluctuating so much and the p0299 because it can't get enough boost.
It's prolly gonna sound stupid, but what exactly am I looking for, with the camshaft? I have not pulled the VC off yet, but it was on my list of "to-do" to replace the vc gasket. How does the cam affect these two codes? you referring to a worn cam lobe(s) or something?

Have you tried a vacuum gauge on the actual output of the vacuum pump? I would tee into the line feeding the N75 and check, should be 25in/hg. I have seen bad vacuum pumps and leaky brake boosters cause these sort of problems. And also, how does it sound at idle? Make any strange "bupping" noise from the intake?
I've tested vac at idle, and it's a easy 23-25in at idle. I will say that the HPFP/VP on the back of the head has an ill-fitting nipple that is what (i believe)to be the main vac source, as it goes directly to the rain tray/firewall area, if my memory serves me.

I've not noticed any strange sounds from the intake at idle. OF course, I won't be able to go verify any of these things you two have pointed out (aside from looking at the cam) until I get the turbo back on.

I really appreciate both of your inputs and questions. At least it makes me feel I'm not fighting this dog by myself.. ;)
 

Mozambiquer

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It's prolly gonna sound stupid, but what exactly am I looking for, with the camshaft? I have not pulled the VC off yet, but it was on my list of "to-do" to replace the vc gasket. How does the cam affect these two codes? you referring to a worn cam lobe(s) or something?


I've tested vac at idle, and it's a easy 23-25in at idle. I will say that the HPFP/VP on the back of the head has an ill-fitting nipple that is what (i believe)to be the main vac source, as it goes directly to the rain tray/firewall area, if my memory serves me.

I've not noticed any strange sounds from the intake at idle. OF course, I won't be able to go verify any of these things you two have pointed out (aside from looking at the cam) until I get the turbo back on.

I really appreciate both of your inputs and questions. At least it makes me feel I'm not fighting this dog by myself.. ;)
Yes, you'll be looking for worn cam lobes. Often they will wear and one of the first symptoms will be a p0101 maf code and a p0299 boost pressure code. You'll also be looking for dished lifters.
Another thing to look at is the EGR valve, make sure it's completely closed, as if it's sticking open, it'll cause the same problem.
 

VariantB3_VR6

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Aug 25, 2004
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Winchester, VA
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05 B5-A, 01 A4-M
Yes, you'll be looking for worn cam lobes. Often they will wear and one of the first symptoms will be a p0101 maf code and a p0299 boost pressure code. You'll also be looking for dished lifters.
Another thing to look at is the EGR valve, make sure it's completely closed, as if it's sticking open, it'll cause the same problem.
I did pull the intake off and the EGR apart and cleaned everything. it wasn't bad at all (shockingly) as my 200k mile ALH was absolutely choked down to the diameter of a #2 pencil with carbon and sludge crap.
The BHW was quite clean. The intercooler pipes have a lot of oil in them, like it drips when I open one, but I think that may be caused by the CCV in the valve cover is most-likely trashed.
I'll look at that, too, when I remove the VC tomorrow morning.
 

Mozambiquer

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@Mozambiquer , i noticed in your Fuelly for the 2005 Passat TDi. you have EGR delete. did that also require a 'tune', per se.?
Yes, I do have an EGR delete, though currently it isn't tuned (I have a rocketchip tuned ECM, but I swapped it into my wife's Passat.) and am enduring the check engine light. I got the car with a bad EGR cooler for $1000, and drove it as the family car after deleting the EGR. Later I got a tuned ECM for it and ran that until I got a couple more Passat wagons. I put the tuned ECM in one of the other wagons and put the original one back to stock, just with the EGR plated off, and I now drive it as my daily driver.
 

VariantB3_VR6

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Winchester, VA
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05 B5-A, 01 A4-M
I just wanna get this back on the road soon. it's fine while the engine and such are cool. Soon as it's at optemp, it starts the dumb sh!t
 

VariantB3_VR6

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Aug 25, 2004
Location
Winchester, VA
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05 B5-A, 01 A4-M
I pulled the VC, didn't see any real signs of wear, etc. I will say, though, for having 400k miles, the valvetrain and inside the head is superbly clean..
 

VariantB3_VR6

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Aug 25, 2004
Location
Winchester, VA
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05 B5-A, 01 A4-M
OK..
  • Valve cover gasket replaced
  • Turbo disassembled, checked end play and wobble: Felt perfect
  • Cleaned Turbo completely - including the VNT section Now it moves like butter. no bent vanes, no sloppiness where the actuator arm moves the ring..
  • New Downpipe gasket, oil drain gasket, EGR Cooler gaskets
  • New hardware (studs, nuts, etc)
  • Checked/cleaned MAF and MAP
  • Checked/cleaned intercooler pipes
  • Removed, cleaned and reinstalled intake manifold, including new gasket
  • WGA tested; holds vacuum as tested
  • Vacuum canister under turbo holds vacuum as tested
Reassembled everything, took it for a drive. Stayed in town, driving around, seemed fine. Spent about 30-40 mins doing this..
Decided now's the time, let's hop on the bypass and get some speed...
Turned onto the on-ramp, accelerated to about 35-40, BEEEEP.. Limp mode.
Went to next exit and pulled over, whipped out the VCDS. P0299.. Requested: 2364mb, 1754.4mb actual.

N75 has been replaced
EGR was cleaned
All vacuum lines replaced
Vacuum check valve replaced
Air Filter replaced

I'm out of guesses, at this point.. Short of buying an EGR blockoff ant 'testing' to see if the EGR is not seating properly, I don't know what else to do..

PLEASE, throw me some ideas, if you have any more.. I'm at my wits end with this car now.
Thanks.
 

VariantB3_VR6

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Winchester, VA
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05 B5-A, 01 A4-M
Ok, I think I'll just sell it, or donate it to Salvation Army or whatever. I'm not gonna put more money into it. Thanks much, guys, for your help throughout this adventure!
 
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