Turbo surging again (but narrowed down symptoms!)

[co004]

Hi All,

When I first had my LC 180 I had an issue with the turbo surging and cutting under load causing a kangaroo effect acceleration. Annoying. Through running VAGCOM and recording the required blocks this was thought to be down to a leak in the system somewhere.

Fast forward 6 months, I bypassed the N249 and because I made a mess of it I introduced a leak in the intake - DV pipe. Now I didn't think about it but all the time I was running with that leak the surging stopped! Last night I fixed the leak, nice solid pipe from the Intake to the DV and now, surging is back on!

Now my first guess (and it is a guess) is that the system is now back under more pressure as there's not a blatent leak and this is causing my original leak to again show itself when under load?

Does this in anyway help to explain where in the system the leak might be?

All help appreciated.

 

[Scruff]

Is it boosting up to a stupid amount then dropping quite violently? I had this on my impreza and it was due to my actuator packing up.

 

[co004]

What's the actuator? N75?

From the blocks I ran before I think it is over-boosting and then cutting it.

 

[psycho6285]

Actuator is on the turbo, controlled by the N75. Looks like a flying saucer with a rod controling the valve in hte turbo

 

[Scruff]

The gold coloured thing on the top left. Its got a spring inside that over time can go soft/break. If it does, this will induce the symptoms you're describing. If you can get hold of a spare/borrow one from a mate, it shouldn't be too hard to swap out.

http://www.autodrager.lt/admin/edit...OCTAVIA 1.8T 180HP UPGRADE TURBOCHARGER/1.jpg

The N75 is your boost solenoid. Definately check all pipes around this for splits as its all connected in one way or another and can give the same problems.

 

[DannyC87]

I cured this kind of surging with:
Removing old split PCV system and fitting a catch can
& fitted new plugs which I gapped to 0.028"
& new MAF

 

[co004]

OK, my engine management light has now come on and I'm getting the following code..

16795 - secondary air injection system incorrect flow detected

Now this suggests there could be a split pipe in the secondary air injection system. Obviously I'll look for that but what's the likely hood of that causing the surging/boost cutting problem?

 

[adam cupra 20vt]

OK, my engine management light has now come on and I'm getting the following code..

16795 - secondary air injection system incorrect flow detected

Now this suggests there could be a split pipe in the secondary air injection system. Obviously I'll look for that but what's the likely hood of that causing the surging/boost cutting problem?

Thats very likely to be the seal inbetween the 2 halfs of the pump as the rivets fail over time.

When mine failed it didn't effect boosting.