BRM Low boost below 1800rpm issue

OMALLEY_808

Veteran Member
Joined
Jul 17, 2014
Location
Canada
TDI
2006 JETTA TDI
- 06 Jetta TDI.
- No stored DTCs
- Torsion at 0.5
- New timing belt water pump/cam/followers
- no black smoke or and strange behavior
- Had hesitation and then boost spike at 1800rpm before
- limited VNT to 160mbar difference and have no spike now
- Boost spec vs actual is low until around 1800rpm and then matches again.

VCDS logging confirms low boost. Until 1800+ rpm. VNT actuator holds vacuum and starts moving around -3 and hits the stop at -17

 
Last edited:

jjblbi

Veteran Member
Joined
Sep 27, 2000
Location
lbi, nj
TDI
2014 Passat SEL TDI
I experienced a similar condition about two years ago with my PD motor. Head had been off car for about 3 months for new cam, followers and head work. Apparently the injectors may become damaged if not kept "wet". I tried many, many fixes and adjustments without success. Eventually installed new used injectors (~$500) and car is back running strong. I am one of 3-4 owners that had this issue after an extended head-off. This may not be your solution but if you had it apart for a while save yourself a lot of grief and try injectors. If that is not the solution you can always resell them. Good luck, John
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Yep, sounds like the normal worn out VNT ring in the ol' BW turbo. Very common on the BRMs.
 

OMALLEY_808

Veteran Member
Joined
Jul 17, 2014
Location
Canada
TDI
2006 JETTA TDI
Could one injector cause this issue or is it definitely the vnt ring? Injector #4 on my car has a deviation of about +0.75 from the rest...

Car idles smooth and runs fine otherwise though...

Yep, sounds like the normal worn out VNT ring in the ol' BW turbo. Very common on the BRMs.
 

OMALLEY_808

Veteran Member
Joined
Jul 17, 2014
Location
Canada
TDI
2006 JETTA TDI
Anyone have an answer if an injector has a deviation of about +0.75 from the rest should be replaced???
 

A5INKY

Vendor , w/Business number
Joined
Sep 4, 2007
Location
Louisville, KY
TDI
2006 Jetta TDI, 2002 Eurovan Westphalia VR6
By either the zip-tie band aide, or actual stop screw adjustment you got Basic Settings deviation at 160 mbar, then I doubt the worn VNT control ring is the issue here. The fact that you had to correct it means the ring is worn and boost control will be sloppier, but it shouldn't cause a lag.

I recommend another Group 11 log but at WOT in 3rd gear from ~1500 RPM to redline. With this log you can graph actual vs. corrected in a spreadsheet program. If you post that it will be easier to judge if it is laggier than usual or not. With the part throttle log you posted you are not requesting the fueling potential in that region of the log, more fuel (WOT) will provide more exhaust energy to get the turbo spinning faster.

As a side benefit to the above log, you can check N75 duty cycle at 4000 RPM to verify the rod length is correct too. It should be around 25-30%.

Actual NEVER exactly follows requested on spool-up, even in a new car. The ECU requests stronger boost response in that region to spool the turbo within it's mechanical, dynamic limits so you will always see actual lower until the turbo can get up to speed. In other words, you may not actually have an issue.
 

fwthompson

Well-known member
Joined
Feb 24, 2013
Location
CDA
TDI
06 jetta tdi brm 5 spd 220k (sold) , 05.5 jetta tdi brm dsg 134k (SOLD), 06 Jetta TDI BRM dsg mkv white. 224k. 2011 jetta cja dsg Silver. 155k
You can check the vnt actuator very easily with a vac pump and guage like a mity vac. It should hold and begain to extend thru the pumping cycle. But holding pressure is the important part. Theres a good write up on adjusting these if you google it. Idparts sells replacments if yours fails the check. Goodluck.
 

scrambld

Veteran Member
Joined
Jun 26, 2004
Location
Belchertown, MA
TDI
'06 Jetta...TDI/5spd :) >>>now a '15 Passat TDI/DSG
Subscribed to see how this turns out. I am still seeking answers for a similar issue with my '06 BRM..........Please post up your findings. thxs
 

OMALLEY_808

Veteran Member
Joined
Jul 17, 2014
Location
Canada
TDI
2006 JETTA TDI
I have a mityvac already. Actuator is fine. Changed the fuel filter with the oil change last week and definitely restored some lost power but it still a dog between 1000 and 1500 rpm in anything other than 1st gear.

I'm still leaning towards that faulty injector. I have a spare set but it looks like a pain in the ass to change...

Fuel mileage is good and car pulls pretty hard for what it is once that malone stage 2 power kicks in.
 

GreenLantern_TDI

Veteran Member
Joined
Feb 27, 2014
Location
Iowa
TDI
2015 GOLF SEL
Dont know if youve read the MKV specific thread but alota people reporting this issue. Normally fixed by ziptie mod but even guys with new turbos having the same issue.
 

OMALLEY_808

Veteran Member
Joined
Jul 17, 2014
Location
Canada
TDI
2006 JETTA TDI
Dont know if youve read the MKV specific thread but alota people reporting this issue. Normally fixed by ziptie mod but even guys with new turbos having the same issue.
Yeah already played with that. Using a zip tie is a pretty sloppy way of doing it though as it can sometimes jump onto the side of the adjustment nut or the actuator arm, it can also jump around on the VNT nipple or land on the rubber vacuum hose. I used stainless steel mechanic safety wire tied nicely at both ends to prevent jumping around and tried limiting it. Same sort of results.

I dug up a thread with someone who went through all the same checks I have and had one faulty injector and when he changed it, it solved the issue.

Here is the theory. One injector is out of wack (leaking/excess fuel) Computer picks up on this and cuts fuel to the other 3 injectors, as seen by the negative duty on them. This results in underfueling down low, which underfueling will not spool the turbo or accelerate as normal.
 
Last edited:

kdawg89

Veteran Member
Joined
Dec 3, 2013
Location
Spanish Fork, UT
TDI
15 Golf DSG 06 Jetta (sold)
+1 for the turbo, I had similar issues and put heavy wire on it to bandaid it for awhile which helped but never totally fixed it. Your turbo is already bad, I would start by replacing the known failed component that is directly tied to your complaint before you start throwing other expensive parts at it.
 

OMALLEY_808

Veteran Member
Joined
Jul 17, 2014
Location
Canada
TDI
2006 JETTA TDI
+1 for the turbo, I had similar issues and put heavy wire on it to bandaid it for awhile which helped but never totally fixed it. Your turbo is already bad, I would start by replacing the known failed component that is directly tied to your complaint before you start throwing other expensive parts at it.
Already replaced turbo, same issue with both units.
 
Top