1.6TDI Golf MK6 Engine Stutter

Yesterday on the way to work travelling at about 40MPH and changing gear the car seemed to loose power and then judder a little and was then ok for the rest of the trio. This morning drove for a 1/2 mile stopped for an hour and then started again and just changing from 1st to 2nd it started to jerk alot for a couple of seconds and then came right. I took it for a drive and all seemed ok. There are no warning lights on. I always buy fuel at a branded station. I am going to telephone the dealer in the morning to see what they say. It is a 2010 with about 40k. Any ideas anyone?

Welcome to TDI Club. Without codes these are all just guesses mate. No priority to list order - just how my brain is working this morning. If I were betting, I'd bet on number 3 as potential root cause. Keep us posted as to what's up.

1. VNC (variable turbine geometry) control issues. It think this would be more likely to result in overboost. Overboost throws codes and drops the car into limp mode. This happened to my 2L TDI recently (~ 14.4k miles). I can't be certain I had a VNC issue, but it hasn't happened again (now at 15.5k miles).

2. CR rail pressure control issues. Under trailing throttle (while shifting) CR pressure probably rockets. Perhaps the controls are dropping CR pressure a bit too far. Then under power demand (after gear change) the engine can't deliver. Because the engine seemed to do well under power before shifting, this doesn't point toward HPFP issues which we are all over-sensitized to expect. I've done some CR pressure logging with VCDS. I've always found that the system recovers CR pressure quite well - so this is not a very likely root cause. Just mentioning it because it passed through my thinking process.

3. EGR transition issues. If your 1.6 is like my 2.0, there is a transition between high pressure EGR (exhaust gas recirculation) at lower RPM and low pressure EGR at higher RPM. If you think about it, during gear change engine RPM shifts may be forcing the engine to shift between EGR modes. High pressure EGR valve may be sticking a bit flooding the intake with low O2 gas while at the same time bleeding exhaust flow that should be available to spin the turbine. This would be my bet in your case. From VW's SSG on 2.0L TDI's:

OT, but your schematic makes me curious - I was under the impression that on a diesel, all throttling was done via fuel flow, not by chocking off inlet air flow. What purpose does throttle valve after the intercooler serve then?

Thanks for your time with the detailed reply.Looking around the forum I seem to be not the only one with issues like this and I presume the emission systems are broadly similar between both types of engines. I booked it in for Thursday at the local VW dealer. The first thing the service guy said was that it sounded like the Regen process. He seemed to have come accross it before. He said that it may still have a fault stored although there is no light showing. He also said that they could check soot load etc which may give an indication if it is pointing towards this. I will post if I make any progress.

Thanks for the heads up. Thanks in advance for keeping us posted. It's a great value to be able to learn from each others vehicle experiences.

No More Buffalo said:

OT, but your schematic makes me curious - I was under the impression that on a diesel, all throttling was done via fuel flow, not by chocking off inlet air flow. What purpose does throttle valve after the intercooler serve then?

Click to expand...

These days emission regulations are central to most of the innovations that are occuring in diesel technology. The best way to get a sense of how this system operates is to read the self study guide for these engines. These are not your daddy's diesel engines anymore. These are computer controlled engines. The narrative (link below) is written for trained service technicians, so it's short on detailed explainations.

http://152.66.93.29/audi/download/vw...rail TDI.pdf

If you look at the CARB (http://www.arb.ca.gov/html/fslist.htm) site you can get a glimpse of what's coming. I honestly think these folks won't be happy until driving is so expensive that we're all pedaling bicycles.

Well I was at the dealer last Thursday and left the car with them for the day. They found nothing wrong ,scanned for faults etc. and all was clear. I went for a drive with the mechanic and spoke to him about the issue. He again pointed to the Regen. So at least the problem is logged should it happen again. But an interesting happened today as I was heasing home from work, after 5 miles and going through a town I noticed the slighest blip not as severe as what I noticed before so I pulled over and a Regen had just started. So this possibly explains what I have been on about.

HI
My 1.6tdi does this at times when in regeneration.
Because this engine lacks power below lets say 1300/1350 rpm, if in gear at lower rpm and when you try to acelerate it may hesitate.
If I´m stoped I usually push 1º gear to then put second and so on.(when in regeneration)
That´s why it´s recomended to drive above 2500rpm when the car is in regeneration. I have also noticed that diferent fuel brands have diferent results in regeneration harshness and how often.

At least it seems a common issue. We learn more and more about these cars the longer we have them.

Common fault on up to 2012 model known in the trade as EGR bump. Dealers have no understanding of it but I found a guy here that sorted it on mine.

I have a 2010 1.6tdi variant in Germany. Every now and then, when cold and waiting at a light, the idle would get erratic, fluctuating from 600-1200 and it would run rough. it would clear up once it got warm. I took it to the dealer who seemed familiar with the issue. If i remember they updated the ECU and the issue has not recurred in the last 1.5-2 years since. It had something to do with increasing the idle speed during regens.

I'll check the receipt if it states exactly what they did.

heidelberger75 said:

I have a 2010 1.6tdi variant in Germany. Every now and then, when cold and waiting at a light, the idle would get erratic, fluctuating from 600-1200 and it would run rough. it would clear up once it got warm. I took it to the dealer who seemed familiar with the issue. If i remember they updated the ECU and the issue has not recurred in the last 1.5-2 years since. It had something to do with increasing the idle speed during regens.

I'll check the receipt if it states exactly what they did.

Click to expand...

For that to cure you need your SW updated to the latest 9971 rev.
I wonder how all those cars did pass VW internal testing. No way they didn't come across that while they were testing the cars with 1.6 TDI