Boost issue!

[Davewilkins]

Hi guys - so after replacing my spark plugs and coil packs tracking down a lumpy idle my car has now developed a very noticeable boost leak/problem. I have changed DV/PCV/plugs/coil packs/MAF/N75. Only mods I have is revo stg1 and a piper cross panel filter. I've got VCDS and I can see that car is requesting boost (2440) and only making 1340 so n75 is at 99%. No misfires now, slight timing pull but ok. Fuel trims at 0.8 and 11 which seems high. Oh and the lumpy idle is still present! Anything I've missed? Or am I going straight to intercollegiate hosed?
By the way it's a 2006 gti axx k03. Any help would be much appreciated.

[Davewilkins]

That's meant to be "intercooler hoses"! Lol

[Davewilkins]

Just in case anyone was interested thought I would check my 4 month old Rev d diverter valve and sure enough to it has disintegrated! Luckily kept my old Rev c so put that back in and car is brand new again! Got a photo of the valve but can't upload it. Shocking piece of engineering on VWs part really!!

[Andy-GTI]

Rev G or a GFBDV+ be the best options to replace the Rev C DV. Doing mine soon also. Glad you sorted issue.

[Davewilkins]

Yeah have rev g coming. Just gotta sort this rough idle out now!!

[Andy-GTI]

Is it shuddering? like through the whole car, worse when cold seems to lessen one heated through?

[Davewilkins]

No mines worse when warm mate. I've seen various soft miss fires on vcds across all cylinders but not enough to trigger MIL. My fuel trim is high ish at 11% so maybe leaking hose somewhere. Could be loads of things tho!

[Andy-GTI]

I really need mine on VCDS to see what mines doing, mine seems better once warm.

What VCDS you use, newbie to the mk5GTI, is it the same as a mk6 version?

with the fuel could it be fuel pump and follower related? more wear on cars mapped id assume.

[beetie]

Strange idle could be due to carbon build up in the head.

[Davewilkins]

Yeah that's on the list of possible things it could be. I've read a few how to guides and it looks pretty involved! I'm not a complete muppet with a spanner but this maybe slightly out of my league. Thing is - do you replace injectors at the same time to rule them out?

[Andy-GTI]

Strange idle could be due to carbon build up in the head.

May run a can of BG44K through mine see if it helps clean some carbon & injectors etc. Heard its decent stuff.

[Davewilkins]

I've just got the wynns direct injector 3 spray to use first.  Same sort of deal - spray through PCV hose whilst engine at 2k plus bottle in the tank. I don't hold out much hope but it's worth a try for £20.

[martin@gti.co.uk]

fuel additive wont work on head port carbon build up on tfsi / tsi

You might try some solvents via temp switch hole at intake manifold, but best thing is just take your inlet off and scrape it off, for best results.

[Davewilkins]

The cleaner goes through PCV or temp sensor hole for the inlet valves And then bottle in the tank for injectors. I'm doubtful it will work but worth a shot!

[Andy-GTI]

The cleaner goes through PCV or temp sensor hole for the inlet valves And then bottle in the tank for injectors. I'm doubtful it will work but worth a shot!

For the price it cant do any harm, so I agree its worth a shot!

Going to go for the PCV replacement on mine also as its not been done, and worth a go for the preventative measures also.

Will report back see if it sorts my idle out. Apologies for thread hi-jacking