After a longer drive outside the city today I noticed the following things:

1. WOT from 2500rpm results in a momentary boost drop at 4000rpm, from 1.6bar to 1bar and back (seen on the boost gauge), otherwise it goes fine.

2. WOT from 3700-3800rpm results in a pretty big dead spot at 4000rpm, but strangely the boost holds at 1.6bar, just the car doesn't go and kind of shakes a little bit. It takes ages to get past 4000rpm at WOT (maybe 4-5 seconds), but once it does it's rainbows and unicorns again and it goes fine from there on.

3. The above simptoms manifest themselves mostly in 5th and 4th gears, and only VERY rarely in 2nd and 3rd...basically in 5th it always does it.

Any ideas? The drive was done at an outside temp of 29 celsius and I've tried with both aircon on and off, it's the same.

(can't do logs yet because I have windows 7 on my laptop and apparently vag-com 311 doesn't get along with it)

Edited 12 June, 201016 yr by jmf

mine has a slight hesitation in 3rd and 4th at similar RPM to yours. I tried a throttle body clean (which made a massive difference to the car) but the hesitation was still there. Im going to try another N75 valve next and look for split hose(s)

Check for split hoses and might be worth taking the fuel filter off and checking it's not crudded up.

Are you sure it's not the clutch going?

When mine started to go, it would slip in 5th gear when under full load on the motorway, and if I kept my foot down it would regain grip at higher engine speeds, as the torque tailed off.

The clutch was totally normal in town and normal driving. Does the engine sometimes shudder when this happens on the motorway?

What clutch/flywheel are you running with that K04?

Throttle body was cleaned about 3 weeks ago. The fuel filter...I'll take a look, it's been changed about 30.000km ago, maybe it's time again

I sure hope it's not the clutch as it's less than one year old. I have the ECS Stage 1 clutch kit, which is the G60 flywheel and the VR6 clutch. Although yea, the engine and the car itself shudders when this happens. However I find it a bit strange that it ALWAYS does it at 4000rpm. When my previous clutch was shot it did it all over the place with no definite "spot".

Another idea that I have is that I AM running a bit lean, the vag-com 032 block shows around -10% for the multiplicative trim, due to the fact that I'm running stock injectors with 4bar FPR, but unfortunately I don't know how I could check if that's causing it.