MK5 Golf GTI

All Things Mk5 => How to Guides / Troubleshooting => Topic started by: Davewilkins on April 13, 2015, 08:43:09 pm

Title: Boost issue!
Post by: Davewilkins on April 13, 2015, 08:43:09 pm
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.
Title: Re: Boost issue!
Post by: Davewilkins on April 13, 2015, 09:49:15 pm
That's meant to be "intercooler hoses"! Lol
Title: Re: Boost issue!
Post by: Davewilkins on April 14, 2015, 05:25:47 pm
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!!
Title: Re: Boost issue!
Post by: Andy-GTI on April 18, 2015, 01:33:58 pm
Rev G or a GFBDV+ be the best options to replace the Rev C DV. Doing mine soon also. Glad you sorted issue.
Title: Re: Boost issue!
Post by: Davewilkins on April 18, 2015, 04:54:47 pm
Yeah have rev g coming. Just gotta sort this rough idle out now!!
Title: Re: Boost issue!
Post by: Andy-GTI on April 18, 2015, 05:30:28 pm
Is it shuddering? like through the whole car, worse when cold seems to lessen one heated through?
Title: Re: Boost issue!
Post by: Davewilkins on April 18, 2015, 06:58:06 pm
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!
Title: Re: Boost issue!
Post by: Andy-GTI on April 18, 2015, 07:17:33 pm
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.


Title: Re: Boost issue!
Post by: beetie on April 18, 2015, 07:42:48 pm
Strange idle could be due to carbon build up in the head.
Title: Re: Boost issue!
Post by: Davewilkins on April 18, 2015, 07:48:29 pm
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?
Title: Re: Boost issue!
Post by: Andy-GTI on April 18, 2015, 07:53:03 pm
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.
Title: Re: Boost issue!
Post by: Davewilkins on April 18, 2015, 09:54:20 pm
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.
Title: Re: Boost issue!
Post by: martin@gti.co.uk on April 18, 2015, 09:59:12 pm
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.
Title: Re: Boost issue!
Post by: Davewilkins on April 18, 2015, 10:17:38 pm
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!
Title: Re: Boost issue!
Post by: Andy-GTI on April 18, 2015, 10:23:02 pm
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 :signLOL: