Would really appreciate some input with my old Superb

See video here:
https://youtu.be/x6R4rOJ-_3w?t=144
(phone on a mount on side window, sorry for vibrations)

 

1.9PD 130 AVF tiptronic with 226K miles on it.
Around 1700rpm the car seems unable to maintain steady revs, dipping / surging by around 250 rpm on a quite regular cycle.

It was in cruise control with the gearbox in manual mode, 5th gear.  4th also does it, and I think 3rd.  Checked cruise mode to be sure there is no issue with the pedal.

Disconnect MAF doesn't make a difference (other than car no longer pulls properly)
No fault codes in VCDS
VCDS timing appears ok (-0.6-0 degrees).

Ideas anyone, or further investigations that make sense with VCDS?
Thanks!

Edited 24 January, 20188 yr by jimbof

hi jimbof

with fact "No fault codes in VCDS "

i would say firstly EGR malfunction

and secondly something to do with gearbox/transmission

just a guess

I see you checked the MAF, would a faulty brake light switch cause the issue as that knocks off cruise?

Edited 29 January, 20188 yr by gfinneran

Jim I have the same engine & transmission combo as yours, mines a 2005 with 324,000 km, (202K in miles approx.) I recently removed & cleaned the EGR and intake manifold and it really improved the responsiveness and running of the car. The car eventually set a check engine emissions light, I had some surging in cruise mode very intermittent hard to pinpoint but would run ok with the cruise off. It would drop a gear even on a small inclines and struggle to regain the pre-set speed unless I knocked it into manual. Running the same route without cruise on it would climb fine in top gear (Auto selected) with no issue, like I said it was very intermittent and i only noticed it on the longer trips where I had cause to use cruise control for extended periods. Since cleaning the EGR and intake I haven't noticed the issue.

@gfinneran that's positive.  Garage suggested EGR strip/clean so I'll probably let them do it.

I used cruise to show it wasn't accelerator-pedal related. It does it out of cruise too.

Jim I would have them do the intake & EGR cooler too if your going to keep the car, there was a fair bit of build up in mine, burned it out with a torch its a dirty job, lots of carb cleaner too. A tedious job more that a difficult one replace the bolts and gaskets too.