No power off idle

Maxamillian

New member
Joined
Aug 15, 2012
Location
Michigan
TDI
Jetta
BRM Boggs off idle

Hey Guys, I'm new to this forum so please bear with me. I own a driveability shop and work on everything. This 2006 BRM Jetta has no power from a stop most of the time. If you floor it while acting up, the valves rattle and a ton of black smoke out the exhaust. Seems like a fairly common problem with these BRMs. I do all my scanning with a Snap-On MODIS. No codes. Replaced EGR Valve with a new VW test unit/result = no better - replaced Boost Pressure/Intake Air Temperature Sensor with new VW test unit because when I unplugged this the problem went away, granted I had no boost though/result = no better. Wow! How can this thing run this bad and not set any codes? It is capable of setting codes as it did when Boost Pressure Sensor was unplugged. There are no unusual noises from engine as I see guys talking about bad cam lobes. Engine starts great, as fast as you can hit the key, idles smooth. While it is acting up, if you lift throttle for just a second and re-stab throttle, it takes off like a bandit. Once you are rolling down the road it runs fine, has boost, etc. So this is an intermittent problem that occurs only off idle, pulling away from a stop. There is no noise from the turbo at all and can feel it boosting once you are rolling. The only thing out of the ordinary is an exhaust leak from the back of the engine by the EGR Cooler as evidenced by the soot all over which I guess is another common problem on these. I pulled a vacuum on the Turbo Vane Cotroller Rod and watched it move smoothly both ways. I ran Basic Settings test 011 and watched it activate the Vane Controller off-on-off-on, seems to work fine and as well, must have a nice vacuum source since this works very quickly when activated. I monitored the Vane Controller percentage as I applied vacuum up to 20 inch pounds and watched it climb from 0% to 102% and was able to watch it climb one # at a time with no drop outs. If I watch this same value while driving, it is at 102% while backing out of the garage and pulling away slowly. Then you go to pull out into traffic from a stop, forget about it! That's when the black smoke, valves rattling, no power problem manifests itself. If you just keep your foot in it, it will not accel hardly at all and the value still shows 102%. Lift throtlle and re-stab it quickly and the value drops to approx 70ish and power comes back. What I did next was to dis-connect the vacuum supply to the Vane Controller, and while there is not a whole lot of power, which is understandable now that the Vane Controller is "Off-Line", there is no more black smoke, valve rattling problem. I did look at Cam to Crank angle and could see it moving approx. half a point during blip throttle so I know that it is a live value and tracking. If I try and run EGR test 003, the engine will quit. I tried running it again while giving it some throttle and it still quit, does this point to anything? I pulled the lid off of the Fuel Filter and it looks great inside. So that is where I am at. I luv working on these little fellas. I just need someone with much more experience than me to guide me in the right direction now that you know what I have for scanning and what I have checked thus far. My question at this point is, why is the computer telling the Vane Controller to run at 102% when the rest of the system is not co-operating? The Computer must monitor desired vs. actual on the Vane Controller, so are these values normal and I need to look elsewhere? And why in the heck is this car running so bad and it doesn't set a code?
 
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MyAvocation

Top Post Dawg
Joined
Jun 9, 2004
Location
Hoffman Estates, IL
TDI
2017 Passat SEL TSI
I don't have much hands-on with the BRM turbo, but it sure seems like this is the source. Doesn't sound like the vane mechanism is broken, since you can coerce it to spool under load. The vane actuator is controlled by the N75. If you're certain there are no intermittent vacuum system issues, then I'd focus on the N75. Maybe search for good explanation/diagnosis of this component.

One thing that comes to mind is the N75 bleeds-off excess vacuum under certain conditions. It's possible this is not happening. Maybe put a vacuum gauge in series on the bleed-off tube and monitor it on a test drive.

Sounds like you're forging new ground on this one. Good luck and keep us posted.
 

ro.sniper

Veteran Member
Joined
Aug 31, 2009
Location
T.O. Canada
TDI
2006 Jetta TDI
Mine does the same thing occasionaly. There are days though which it functions really well and it goes right off the line if you mash the go pedal. If I floor it really hard it bogs, but the tap tap acceleration works well... I fixed some of the issues by EGR deletion and zip tie on the actuator.
 

MkVer

Veteran Member
Joined
Oct 18, 2010
Location
NM
TDI
MkV Jetta BRM
I've replaced both my EGR and CAM and your description isn't either of those. I'd be inclined to look at the N75 as well. Though I'm also curious about the MAF.

As for the No Codes, it happens. When my EGR started failing it would regularly kick the car into limp mode, only about 1 out of 10 limp modes would give me a trouble code.
 

Maxamillian

New member
Joined
Aug 15, 2012
Location
Michigan
TDI
Jetta
This vehicle is fixed without replacing the Turbo. Very
minimal responses but we do appreciate the ones who did
respond. This seems to be a fairly common problem and not
always the same cause. In our case, after looking at EGR,
Mass Airflow, Boost Sensor, Fuel Filter, which seem to be
all common issues to not overlook, the problem was the
Turbo Vane Controller System. These turbos get a lot of
blame and for good reason. The only way to get the Vane
Controller is to buy the turbo assembly. This was confirmed
today as I called my VW parts guy who is real sharp and He
confirmed this and guess what? They carry them right in
stock. What does that tell you when the dealers are
carrying certain parts in inventory, THEY ARE SEEING A LOT
OF FAILURES! My cost was $945.52. This is not newfound
information as you VW Gurus have known about this all
along. But hope is not lost. Let me share with you what I
found after help from IATN, Identafix, and TDI Club (you
get pretty desperate after a while) First, my problem was
intermittent with no power then power, so most of the time,
if a turbo is shot, it won't make power period, it won't
come and go. If a cam is bad (yet another common problem)
the problem is constant, you will have associated valve
train noise and can hear it through the intake and/or
exhaust. So determine that the turbo is ok by removing the
intake boot feeding air to the turbo from the air filter
box. Reach in with a finger (engine off of course!) and
feel the little wheel for any play up/down, in or out. You
can then have a helper start the engine and watch the wheel
as engine is started to be sure the wheel begins spinning
as soon as engine is started. Then have them rev the engine
some and listen for any noises coming from the turbo
itself, you may hear some odd intake noises as the intake
flapper runs thru its range of open to close etc., this is
normal. Just listening for any bad scraping noises etc.
Then shut off engine and watch wheel coast to a stop, it
will spin for a few seconds after the engine is shut down.
Next step is to see if the car has been using a lot of oil
or smoking out the tail pipe, this will happen if the seals
go bad in the turbo, another indication of a bad turbo. You
can also dis-connect the lower intercooler hose and check
to see if there is a lot of oil in it. Note that it is
normal to have some oil in these hoses as the breather
dumps from the valve cover right into the intake side of
the turbo, so don't be alarmed if you see "some" oil. If
things look good so far, the turbo is more than likely
fine. We need one more test. You will see the vacuum pod
that actuates the turbo vanes sitting right next to the EGR
Valve centrally located at the back of the valve cover.
This has a three pin connector that plugs into the top of
it. If you look closely toward the bottom of this unit,
pointing out the front is a vacuum nipple. And yes this is a
vacuum operated pod, not a boost operated pod like most
other turbo systems use. Hook up your vaccum pump to this
nipple and pull 20-28 inches of vacuum and watch with a
flashlite the rod that comes out the bottom of the pod
assembly and see if it moves down, under vacuum, and pulls
back up (from internal spring pressure in the pod) when
vacuum is released. It will move approx. an inch or so. If
it does not move, then you have to pull the turbo,
dis-assemble, clean the vanes, ring, etc. Not a big deal
once you get the turbo on the bench. It's a basic system.
We do this often on Ford 6.0 engines a lot. Ok, if the rod
moves freely, we can bet that the ring and vanes that are
connected to it are moving as well. If you have VAG
software (at this point, you need it) I will reference the
MODIS, you need to monitor the sensor that is in the top
portion of the Vane Actuator Pod. This sensor monitors
where the vanes are in relation to vacuum applied. The
reading will be 0% with no vacuum and 100% with full
vacuum. Now here is where we get to the meat and potatoes.
If you see the full vacuum go beyond 100% like I did at
102% this is where the problem is right here! The software
is not programmed to "see" anything over 100%, so it goes
into "Stupid" mode (black smoke, valves rattling, extreme
loss of power). You can actually watch this value with the
engine running and watch it change while driving etc. It is
normally full vacuum idling and low speed manuevers. Here
is how you access this info on the MODIS - Hopefully you
have European software - go into European/then VW/then
select VW from next line-up/then Expert Mode/enter yes past
the next few steps and warnings/then pick "01 Engine
Management Master"/then "read Measured Block Values/the
next step you have to manuaaly enter what value you want to
see and this will be "043", field number 2 is the Vane
Controller Position Sensor. Ok, so what happens is that
over time the Vane Controller rod moves further than what
it is supposed to due to wear on the internal stop in the
turbo. So because of this, a new turbo is recommended.
There must be a better answer, right? What I did was to
make an external limiter (made out of a coat hanger) that
hooked around the south end of the Vane Controller Rod and
the upper end hooked around the vacuum nipple of the pod.
You have to experiment with the length of the limiter. If
you watch the 043 value on the scanner with full vacuum
applied you are shooting for about 90%. Keep in mind that
that little pod is pretty strong and pulls pretty hard on
the new "Limiter" so you might have to start out a little
shorter. In summary, this system works fine as long as you
can keep the Vane Actuator values under 100% and you won't
have to replace the turbo. Let's face it, coat hangers are
cheap and easy to come by. I want to give credit to the
fella who got my brain working on this one who used a wire
tie to hold up the Actuator Rod on his. He had actually
pulled apart his turbo and found the stop was worn and made
a new one inside the turbo which is more of a permanent
fix.
 
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oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Holy Long Post, Batman! All that to say "The VNT vanes were stuck" LOL.

Well, glad you got it fixed. ;)
 

ro.sniper

Veteran Member
Joined
Aug 31, 2009
Location
T.O. Canada
TDI
2006 Jetta TDI
I believe Jnitrofish was the first to discover the "zip-tie" method of fixing the issue. You have a lot of good info in your post!!

Also my ziptie broke so I am now at the coat hanger...

Essentially when the zip-tie broke I heard the turbo make way more noise than it used to and was getting the jerking. The coat hanger fixed it. I do believe the turbo may be on its way out as it was making an initial small squeal when the zip tie was not holding the actuator rod from going past 100%. Oh well scroll PD140 turbo on the way...
 
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