B5.5 Passat BHW TDI violent shudder on hard acceleration...

[dieseltechMK2tdi]

Ok, I am one to figure out problems on my own, but i am 700 miles away from my tools, shop and home in N.Y. i am in North Carolina helping my parents rebuild after Hurricane Helene.... anyway i drove my 2001 Passat BHW tdi 5 speed manual GLX 4 MOTION swap wagon down with a 6X12 trailer behind me. i recently swapped a perfect running built 2004 passat BHW engine into my 2001 GLX V6 4 MOTION wagon a few weeks before trip, i did the ECU tune from auto to manual, and a 200+HP tune according to the "calculator". i also did a balance shaft delete when i built the motor in the test car and parts passat, before my trip i did a giant turbo, new pierburg tandem pump. new turbo boost pipes and O rings, FMIC, 3" turbo back exhaust with 4 chamber muffler. new a/c compressor, all belts, pulleys, tensioners, cooling fans, radiator, a/c condensor. complete new mild lift suspension, KYB's to give it a good ride. skid plates and 4 wheel brakes, new oversized tires etc. TDI fuel tank, pump and system swapped in..and ANYTHING else that was in question for safety on a long trip to the devastated area. car drove amazing around town and on a few highway blasts before i left. 2500rpm at 85MPH, it cruises awesome, smooth and straight. drove the 700+ miles 80-90MPH a few blast to 150MPH toying with a mustang... no issues, no quirks, flawless.. but recently on one of my many trips to TN for gas for generator and building supplies, i noticed a slight shudder around 1600-2500rpm at light throttle just maintaing speed, it would go away if i gave a slight bit more throttle. so i did the basics, tossed in a new fuel filter again, checked air filter, checked (new) MAF physically and with VCDS. EGR is in "off road" mode. checked CV joints, checked motor and trans mounts(all new at swap) i was able to get it up on a lift to check clutch/flywheel etc. lookd at everything i could and didnt see why this was happening. no codes. fast forward another week, light throttle shudder has gotten slightly worse, but a new thing has happened, under hard acceleration from 1800 to ?? to who knows, because i let out of it for fear of breaking my only ride home, but engine will violently shake, like the engine wants to eject itslf from under the hood. i have driven HMMWV's at 75mph that were smoother, (those of you who know, you know...) anyway.... no white or grey or black smoke that i can see when it does this. boost is normal 25 spiking to 30 psi..... on medium throttle shudder is "ok".....ish.. but still feels like its shuddering ever so slightly slightly, but its a random shimmy. not like a misfire. i just got done swapping in an injector harness, still the same old program... the new tandem pump was a pierburg and i tried to avoid chinese parts, but that was made in china!! yay! i am waiting on a set of good used injectors with new o rings to try next but i am at a loss. i am an old school mechanical diesel guy. although the computer makes them run better, and easy power and tuning and all that, they sometimes suck to diagnose with no codes to give me a clue... but i must "embrace the suck" of the situation and i need to figure this one out. sorry for the long post but i wanted to include as much info as i can remember on what mods, and symptoms i have, because i have limitted cell service, only when i go about 40 miles from my parents i have service and can check this. thanks to everyone in advance for any help or light you can shed on this problem. Chris

 

[Lug_Nut]

from somewhere in the middle of that:

...checked CV joints...

How? Were you able to apply x hundred lb*ft of torque, by hand, on a 2 inch diameter axle shaft, to mimic the copious amounts applied by that beast of a BHW you've concocted?
From your description of the conditions at which the symptoms are present, the length list of modifications, the added load of a trailer on acceleration or hill climb requirements, the unknown pre-swap state of the v6 axles, from all that, I'd start with the CV joints, inner and outer.

 

[zzdiesel]

Were your new motor mounts hydraulic ones? Oil filled.

 

[dieseltechMK2tdi]

from somewhere in the middle of that:
How? Were you able to apply x hundred lb*ft of torque, by hand, on a 2 inch diameter axle shaft, to mimic the copious amounts applied by that beast of a BHW you've concocted?
From your description of the conditions at which the symptoms are present, the length list of modifications, the added load of a trailer on acceleration or hill climb requirements, the unknown pre-swap state of the v6 axles, from all that, I'd start with the CV joints, inner and outer.

up in the air 3rd gear throttle and brake applied enough to load axles but allow wheel to spin. axles stayed straight and true..... no wobble, they were ALL new Raxle heavy duty less than 2k miles ago, the amount of $$ i sunk into this thing was a bit absurd upward of $18,000 in mods and repair parts alone, i tried to stay all OEM or better quality...
\

 

[dieseltechMK2tdi]

Were your new motor mounts hydraulic ones? Oil filled.

yes OEM NOS hydraulic motor mounts and new trans mounts, the motor mounts i have reinforced with 1/4" aircraft stainless steel cable from subframe to aluminum motor mount bracket in case of motor mount failure,... that happened in the V6 that i built a custom intake with eaton M90 supercharger and E85 fuel system on, it regularly broke motor mounts and front snub mounts during hard launches with all 4 slicks until i got the wheel hop problem fixed... ..

 

[dieseltechMK2tdi]

I swapped in the used 40k mile injectors with new elring brand o rings and seals, adjusted the rocker as per Alldata and "myturbodiesel" settings without all the fancy vw tools... the car runs better, down on power because smaller stock BHW injectors, but still has slight shudder from 1600-2600 rpm, light throttle, the massive shudder under full throttle is there but much harder to achieve. before injectors, flooring throttle at 1800rpm it would accelerate to boost about 26-2800rpm, as soon as 20 psi hit it would start to violently shudder, now it only does it when boost spikes to 33+psi but if i keep below that, no full throttle issue. i am ordering the banjo m12x1.5 bolt and banjo fitting to AN3 and a AN3 to 1/8" female SS braided fuel line and a glycerine filled 200psi pressure gauge to check my tandem pump as i have oem vw gauge back home, **** spot on the inline setup to do it, but i am wondering if i have a low fuel pressure issue, my in tank lift pump is set to 10 psi with a 20 psi rise on boost regulator.

 

[PickleRick]

With that area (I'm not too far east of you) getting hit so hard with flooding I would first suspect contamination of fuel if the issue began after a fuel up.

I make lots of money from water in the gas.

Fuel injector companies make lots of money from gas in the diesel

 

[dieseltechMK2tdi]

With that area (I'm not too far east of you) getting hit so hard with flooding I would first suspect contamination of fuel if the issue began after a fuel up.

I make lots of money from water in the gas.

Fuel injector companies make lots of money from gas in the diesel

thank you, i didn't think of that, i will pump out the tank and see if i see anything, i did toss a new fuel filter on and drained the old one, didn't see much other than a tiny bit of what looks like very fine sand. but i am assuming the HENGST fuel filter i put on before my trip would have caught most contamination.... but maybe, so thank you, i will check...

 

[dieseltechMK2tdi]

drained the fuel tank today, took lift pump out, cleaned tank with clean rags and vacuum oil drain tower, nothing out of the ordinary other than a tiny bit of a very fine white dust/silt, same as what i found in the filter when i cut it open... decided since i was this far, to change lift pump and hoses, installed a VDO lift pump 3B0919050B from FCP...
blew out all fuel lines to front and flushed with kero/ATF mix, the ATF has high detergent properties, plus lubrication. put it all back together, new lift pump will only make 7 PSI dead headed and 5 PSI running idle, took it for a ride, kind of sluggish, took pump out, pressure checked all hoses with air and a gauge, did not bleed down, so tossed OLD pump back in and have my 10+PSI at idle.. at this point i am at a loss, it sucks to fire parts cannon at this car, really wish i was at my shop with all my equipment to properly diag this thing. thanks again for all the great suggestions.

 

[Crazymr2]

Did you ever figure out what the problem was? If so please advise.