slight boosting issues

[andyg plym]

ok chaps have a go at this one

car boosts to 1.8-1.9 bar which sounds fine until i mention the car is a bit hessitant at that level of boost. the needle on the boost gauge ever so slightly flutters and the car seems to vibrate/slightly shudder.

was mapped by mihnea a few years back and is Rs2 spec all the way apart from.....fuel pump, which is one of the things i suspect may be an issue. Also has 7a cams in which I DONT LIKE !!

Also when you change gear (every gear) the car seems as if it hits a flat spot until boost picks up again, i was thinking possibly isv.
done the usual boost leaks etc
going to clean the maf and isv tomorrow but want to know if any one has been here before

[andyg plym]

had another brief look at the weekend, my maf is a bit dirty due to oil from my maf hose. this perhaps is coming from the turbo.....

ive had this a few times before on my other s2's but it never caused much of an issue.its not excessive amounts although i know even a bit may upset the maf. ive never run as high a boost set up at this before tbh.

going to use ipa/brake cleaner etc to carefully clean the maf and see if this fixes it temporarely to confirm its the oil from the turbo.

[andyg plym]

maf cleaned but still same

anyone??

[T2Andy]

spark plugs to much boost .

[andyg plym]

plugs fairly new and i did turn the boost down slightly but still got a vibration. feels like its under the car, propshaft wouldnt be a possibility?

[T2Andy]

I had a slight vibration when under high speed and load on my old engine occasionally but went after new set up fitted , i was thinking flywheel or clutch as these have now been changed ,did feal like something was out of balance slightly.

[andyg plym]

yes thats a feeling i have, its only right up in the high boost range, and under load.
i know my tracking needs doing soon but doubt it could be that

[T2Andy]

so it could be engine speed related not necessarily boost related , ionly had 1.4 bar boost

[A80Avant]

the oil on the maf is coming from the pcv system, not the turbo

[DJones]

I had this problem on an A3, i appreciate the power levels are significantly different.... but this A3 would vibrate under load and speed, perfectly smooth when coasting.

I re-greased all the universal joints on the drive shafts (which in truth were a little dry) and the problem went away.

Spoke to a friend who had heard this before......

Check all your mounts are in good order to.

[andyg plym]

interesting guys i must say. is there a way i can grease up the shafts? ie nipple etc? I will deffo check mounts as you have to be gentle on gearchanges etc as you all know these boxes dont like to be rushed.


Pcv system, hmm i suppose it would make sense as ive had knackered turbos before and they use lots of oil, but i cant remember the last time i topped the engine up. Pcv would make sense in that all the gunk could be coming through now from over the years.

[Rusty]

Fluttering boost is either N75 duty cycle or a boost leak IME. The juddering sounds like a boost leak...

The flatness you describe can be down to a boost leak or a poorly operating DV.

I don't think the MAF or ISV have much to do with it TBH.

Get a new DV or service the one that's on there, then test the whole system as close to 2 bar as possible to see what's leaking.

Other options are spark plugs are loose or knackered, as above.

[andyg plym]

boost now turned down slightly since 1st post and not fluttering. plugs recent and all boost pipes replaced.dumpvalve almost new
its engine speed related imo.

[andyg plym]

still got this. can someone tell me if a dirty wgfv may be the cause? wonder if the oil from a choked breather system may have clogged it up?

Lokking for an excuse to get one of those heavy duty ones on here