stuttery agu (fixed)

[Screech16v]

Hi guys my agu is running abit funny after about 20 mins of driving.I ve done a search but still not sorted it, the symptoms are when cruising on light throttle the car seems to hesitate ,a little jerky and its very annoying, this only happens when car is fully warmed up,i changed the coolant temp sensor and stat as these were failing,new plugs bosch super four ,new forge 008dv (yellow spring),replaced vac lines,cleaned the throttle body and checked for vac leaks ,,doesn't seem like a misfire to me just a loss of power sometimes ,vacuum pressure on idle is 8psi and peak boost is 15 psi and drops off some in high revs,i presume this is normal for a ko3 as it can only shift so much air,ive scanned it and have no fault codes ,really want to sort this quickly so any ideas ,throw them up please 

[212hpdazza]

Dude how did u check for leaks the best way is to spray easy start along the pipes if u get hi or dropping revs it's the pipes mine was fluttering from 650-900 rpms then it just started sitting at 12-1400 rpms fora good few seconds b4 dropping back down to 825 hope this helps

[rockmonkey69]

As above, I would also check for boost/vacuum leaks, it's quick, relatively easy and cheap. There are a few tuning garages local to me that have a nice smoke test with the latest UV light feature. It's just nice to know you have no leaks in the system. Perhaps you could ring around a couple of tuning garages local to yourself and see if there are any garages with a smoke machine.

[Screech16v]

Dude how did u check for leaks the best way is to spray easy start along the pipes if u get hi or dropping revs it's the pipes mine was fluttering from 650-900 rpms then it just started sitting at 12-1400 rpms fora good few seconds b4 dropping back down to 825 hope this helps

I checked for leaks just visually so far as ive had the whole lot apart because its all new,will try the old easy start trick though,other than this tiny niggle it runs perfect cheers 212

[Screech16v]

As above, I would also check for boost/vacuum leaks, it's quick, relatively easy and cheap. There are a few tuning garages local to me that have a nice smoke test with the latest UV light feature. It's just nice to know you have no leaks in the system. Perhaps you could ring around a couple of tuning garages local to yourself and see if there are any garages with a smoke machine.

Well if I cant sort it then this is probably what I will have to do,thanks for the info on the smoke test im new to owning a turbo engine and have learnt loads already  would vag com show whats going on?

[rockmonkey69]

Vcds can provide some assistance but it is limited and not always effective for a boost/vacuum leak test. Sometimes it will bring up a warnin of a pressure drop between turbo and throttle body -  check dv! Dtc. It's no substitute for a smoke test though, not least because it doesn't provide much of a clue as to where your leak is.

[Screech16v]

Ok mate cheers ,struggle to believe its a leak though as every ting from turbo to throttle is new and im quite meticulous when putting it together,will get it checked out though as said its nice to know theres no leaks,what about breathers,would these give similar symptoms if one was split ?

[rockmonkey69]

It's unlikely, there are a series of one way valves between the breathers, a leak in the breather wouldn't be much different from a cath tank vented to atmosphere.

[Screech16v]

Nice one for the informative replies fella  will post up when I nail this thing.

[212hpdazza]

The oil breather that runs from the centre of the block to the bottom of the manifold are the normal to go wrong the 1 under the manifold is the 1 that was making mine rev up n down and sticks at 12-1400 revs b4 dropping to 825-850 or it goes the other way and revs from 825-50 down to 650 hope it helps mate