GolfGTIforum.co.uk
Model specific boards => Golf mk4 => Topic started by: Screech16v on 09 December 2012, 22:59
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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 :wink:
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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
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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.
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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
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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 :smiley: would vag com show whats going on?
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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.
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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 ?
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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.
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Nice one for the informative replies fella :wink: will post up when I nail this thing.
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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
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AGU wont see a pressure drop, it will just run like crap.
A leaky/boost leak will cause bad running all the time when driving.
If its after 20mins of driving, i guess its fine when warming up and acting funny when fully warmed up??? whats your temp gauge doing?
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AGU wont see a pressure drop, it will just run like crap.
A leaky/boost leak will cause bad running all the time when driving.
If its after 20mins of driving, i guess its fine when warming up and acting funny when fully warmed up??? whats your temp gauge doing?
Hi chris, yes mate its fine when warming up ,my temp gauge was all over the shop and I thought this must be the issue so I replaced the stat and the temp sender,now it seems to warm up at the correct rate and stay solid at 90 but still have this jerkiness on light throttle giving my engine mounts a little workout.
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any better with maf disconnected when stuttering?
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Ive not tried unplugging the maf yet, i changed the fuel filter and tried another fuel pump relay today,it does seem better but not 100% convinced yet,maf is new but none gen :undecided:
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maf is new but none gen :undecided:
uh oh
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patent parts - in particular when it comes to the MAF, is often a case of hit and miss. Although it is quite deer for genuine MAF it does prove a worthwhile investment.
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So can my cheap maf be tested to see if its doing the job correctly?
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Dont think so.
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Its the MAF everybody its the MAF :laugh: Why on earth did I think I could get away with a cheapo version :grin: Unplugged it stutter gone, plugged it back in and it was back like night and day,so running without until I get it sorted,i noticed with MAF unplugged there is very little boost,is this a kind of self protection kicking in?
Thanks for all your help guys ,now I need to get back to the mk3 section before I start fancying a 4 :grin:
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So can my cheap maf be tested to see if its doing the job correctly?
With Vagcom or on a dyno - yes
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Genuine maf is about £70 with surcharge.
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but the one you give VW has to be a genuine one too -
I had one on my car and when I took it into VW they said its not genuine so you need to pay the surcharge too which was around £50 so MAF ended up like £120 all in, got one from GSF for about £60-70 and its been fine
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When I bought the engine it didn't have one so I don't have a gen one to chop in against the surcharge,so I got a cheap one from uk diesel parts on the bay listed for 1.8t a3,now im on the look out for a gen,is there a specific part number to look for all I know is the agu engine code and don't have the reg of the doner car,suggestions?
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Take the sticker off and you cant tell? All the same housings.
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Very cunning :cool:
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let us know, because mine didnt have any stickers on and it was something to do with the numbers on the housing......... they refused mine in exchange
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Dont htink they checked mine...just put it in the box and that was it.
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Got a secondhand genuine one ,seems to have solved the issue, fingers crossed,thanks fellas :wink:
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Did 120 miles tonight ,car running very smooth with the genuine maf,what I have noticed though is im down on boost slightly compared to the cheap maf,whats happening now chaps ?
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probably reading right.
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If that's the case,would it have been runnin a bit lean then? i guess the cheap maf may have been over reading.
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no idea. as long as new maf rads fine then its oke.... whats boost psi like?
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no idea. as long as new maf rads fine then its oke.... whats boost psi like?
Well it was boosting to 15psi but now only 11 max and drops off in higher revs is this normal
Edti.. also when engine is not up to temp it seems to have restricted boost not that I cane it when cold but I know a guy whos agu doesn't seem to do this
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Guess your mapped?
Any logs you can do with vagcom? Could be 'new' maf is under-reading loads giving less boost?
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Under reading over reading I just want one in the middle :cry: :grin:
It will have to do for now,get crimbo out the way first .