Overboost protection, please help...!

[LHD_Kid]

Hi everyone,
I have read alot of threads about overboost protection coming in and violently cutting the boost... Well this is what is happening to mine now. The strange thing is, it has happened immediately after changing from stock 3B airbox (with K+N panel filter) to an Apexi cone filter. This means the only part of the boost tubing (which was previously holding boost fine) that was removed is the MAF. This makes me believe that it isn't a boost leak causing this.
I want to clean the MAF but IPA is not available in Romania, is there any reason why I should not use carb cleaner spray? I can get that here, or maybe acetone (nail varnish remover) Please let me know befroe I kill my MAF by using the wrong stuff...!
When I first had the car, this overboost problem was apparent, and not knowing anything about it I took it to a turbo specialist friend of a friend... he said he had to replace the MAP sensor in the ECU and that sorted the problem. (I dont knw if thats what he did, but the car has been fine for 6 months now.
Could a simple swap of air filter cause this? Could the cure be to wind out the preload on the wastegate spring a touch? I have a funny feeling he did something with this, was whe I got it back originally car worked fine (hot day) then when it rained and I booted it down a slipo road onto the motorway overboost protection came back, I returned to him and he "backed it off a bit" Again, I dont know what he did, but it was fine again afterwards,
The 3 main culprits seem to be dirty MAF, boost leak, and MAP sensor.... is this correct...?
Thanks for any help or advice
Chris

[quattronutter]

a split hose pre turbo will cause similar issues,check the condition of pipework between maf and turbo intake,it usually splits where its clamped to the turbo...

[LHD_Kid]

I pressurised the boost pipes (also pcv,etc) and no leaks are present....
Any other ideas...? It worked better today, it is warmer, would it make any difference? if colder air is being forced in, boost would be higher? I am no mechanic... maybe it shows...

[stevieyid]

I changed to a Apexi cone filter and had the same. I put it down to heat soak. I changed back to the original air box and it was a lot better.

[LHD_Kid]

Hmmm, I wonder if it is an Apexi thing, it can't be heat soak as the car did it whilst driving along, not having stopped once, and within the fiorst 10 minutes of driving...
Why would this not happen with some "monster" cone filters I have seen some guys using....
I still wonder if a very small tweek on the wastegate spring would be an idea, maybe half or full turn back........

[stevieyid]

Well i think mine was down to my heat shield to be honest, it was rubbish. Mine did it while going along which was i thought it could not be heat soak. I then changed back and it ok now

[porkkis]

Check for boost leaks. It may also be "too much air mass" protection. Boost leaks cause that.

[newsh]

You can use brake cleaner to clean the MAF its usually IPA based, acetone will melt the plastic Clean the MAF connector contacts carefully and be sure they are making a good connection. Plug back in and try again.

Incidentally, FWIW I have never ever cleaned my MAF, only ever the connector contacts..

[LHD_Kid]

Right...
I have cleaned the MAF carefully, and also the contacts using carb cleaner...
I have also done a complete boost leak test, and it holds pressure very well...(there was a tiny tiny leak from the clip on the MAF hose after the MAF, but made no difference sorting it)
Drove up the road, on almost full throttle it is fine, boosts reasonably well, get a nice sound from the TBV on gear change, just as you would expect...
Problem still happens when my foot is right down, boost builds up as normal, then cuts right at maximum power. It makes no difference if you drive through the gears hard, or lean on the throttle gradually building.... once it gets up there it cuts immediately....
I am convinced the wastegate spring has been played with.. will this cause these symptoms if it is wound out or in too far?
I am coming back to the UK in 2 weeks, so anything I need to purchase really ought to be got at that point, I have already replaced the TBV, most of the pcv system and the WGFV, vacuum hoses also replaced, but as I said, its not got a boost leak as far as I can tell, (well, only through the oil filler cap if I go too high............... )
Any more ideas chaps...?
Especially regarding the wastegate adjustment....

[stroker]

Wastegate diaphram maybe torn

[newsh]

Unscrew the wastegate screw untill the screw comes just to the top of the thread (about 5mm below the top surface of the cap) thats a safe place for it, count the turns so you can put it back if you want to. In fact measure how far down it is at the moment.

See if it makes any difference.

Check your Atmospheric Pressure Sensor, in the LH side A pillar at the bottom, look for the thread on how to check/adjust it.

[LHD_Kid]

Hmmm, I was soooooooo sure the wastegate adjustment would be needed... Seems the screw is in approximately where you suggested John.... I dont have a meter here, so there is no way I can check the APS (although I have read a load of posts on this, and I don't think the symptoms are quite the same...)
The main thing I have gained from reading a huge amount on here today, is that there might be an oil problem. I know the rocker cover leaks like a b*****d, and it is caused mainly by 2 of the fixings spinning in their holes,,, I have a gasket and helicoil kit waiting for me in the UK to redress this, I was wondering if oil on the plugs / leads / dizzy or such like could cause this...?
The nearest exact match to my symptoms was a guy who had coil pack breakdown... but this was on an ABY...
My problem started when I put on a cone filter.
I have made up a very elaborate heat shield in sheet aluminium, double skinned 1.5mm thick, cold air feeds from 3 places to the air filter area, which is also mainly enclosed in a bespoke aluminium box (not completely encased)
The moment the cone was used this happened... why?
How do other people run big power, higher boost levels and a cone, without these symptoms....?
I have even tried checking for boost leaks again, just to be sure... but nothing...
I am really getting worried about this, especially as there is nowhere here to take the car for either VAG-COM or a check by someone who knows what they are doing...?
I just need to check through everything in a strategic order as much as I can, but with very little equipment here.
I think the diaphragm is ok, as it holds boost reasonably well, as long as you don't floor the throttle, and ofcourse it was ok immediately before the cone...

[newsh]

You don't need vagcom, you can read the blinks.

If you have lots of leaking maybe the one way valve is duff and you're pressurising the crankcase on boost.

[newsh]

Oh yes, with the APS you could just take the cover off it, give it a clean and a wiggle, my car has not had one single overboost cutout since I did this.

[LHD_Kid]

John, not sure what you are saying about the one way valve? whichg valve is this...? TBV? or one of the ones in the pcv?
TBV is a new Miltek one, and both valves in the PCV system are also new... (as is the WGFV)
I will try the wiggling and cleaning trick on the APS tomorrow, and also blink to see if there are any codes present...
Will post up any findings and hope it pushes me to an answer...!
Cheers
Chris