BRM bobbles in low load low boost fueling conditions...

My brother had a MkV early BRM... I say early because it is "special" being that the clutch doesn't match up to what the VIN says, and the Fuel filter is odd, being a different design than other BRM. I know this because I own probably 5 MkV Jetta Tdi's in our company, and his was the first one we bought, which was one of the first into the country I am guessing. They do not share fuel filers, and have odd little differences. My parents have two Touareg Tdi's (V10) and one of which is currently under the knife for cat/dpf delete and a mild tune. My brother has now purchased a MkVI Jetta Sportwagon TDI and so I may inherit the old jetta as a DD (I have a 3076r 2001 Audi A4 and a 2500HD Duramax)

Any event: My brothers car seems to have issues in the low end. Before the turbo spools it stutters/bobbles and shoots out a knasty black cloud then the turbo spools and it seems to run fine. But low end/low load fueling is screwed.

I have done the searching and research... and am wondering what people can tell me about these injectors and their primary injection off the lobe, and if scoring in the ball or cam lobe can cause these issues?

The EGR has been replaced fwiw.

Update:

Looking at the fuel system... there is carbon in the filter... so looked into the tank... covered in carbon. This leads me to think Bad fuel was run through this motor... then the injectors started wearing on themselves (94k miles) which leads to blowby effect in the injector contaminating the return line.. which contaminated the entire fuel system...

Anyone had this happen to them? And what is the common method of cleaning the fuel system... if I put rebuilt injectors in I do not want to end up ruining them with the carbon that is in the tank now.

My idea was to add a inline filter between the lift pump and motor, but prior to running force feed some sort of cleaning agent through the whole fuel system... make sense? Should protect the injectors?


I can say with the bad comes the good... if the injectors are fubared... I think I will replace with some 150 nozzles and get a tune with water meth. After all it is a daily driver

Turbo is limiting item..not fuel.. You may have bad cam..bad EGR cooler(loosing boost and drive pressure).

Could be Timing and/or carboned up...

I would scan and check..

What is odd is that it idles perfect, and within all the factory specs as checked through Vag-Com... and once the turbo spools it pulls fine, its between idle-spool that it chokes, coughs, and stumbles then puts out a huge black cloud and then cleans up when it gets to boost.

At idle if I floor it and the motor loads up (not in gear) it will do this as well, and proceeds to kill the ozone

I am a noob as far as TDI tuning... my diesel tuning experience is with EFIlive and Duramax's... which I wish every VW/Audi had a program like EFI!