Power loss

[Mk5matt]

HI Guys,

Bought my mk5 gti this year and absoloutly love it. Unfortunalty had a problem over the last couple of days!

Recently fitted an induction kit and had a full turbo back exhaust fitted by powerflow they also stage 2 mapped it for me didnt get a print out as no rolling road. Was told it was around the 250/260 bhp mark.

Car was driving amazing until a consistent missfire. Changed all the spark plugs and coils = miss fire gone

Now over the last couple of days it feels like i have to blag the crap out of it and it's not accelerating like it was. There isnt any warning lights on the dash or any noises coming from the engine. Doesnt feel anywhere near the 250/260 bhp it wss before and more like 180/200 bhp

Have had a friend say it could be the humidity in the air but seems like a big difference to blame on weather.

Theres a 10mph difference on straight roads a few of us run usually late at night

Any help would be appreciated


Matt

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[GTIEagles]

Check your DV for any splits

[DavGTI]

Check your DV for any splits

Yep this. Especially if it’s been in there a while before having it mapped. Something you should consider changing before a map 

[Mk5matt]

Thanks for the advice! Didnt get told abojt the dv before a remap but its done now so hopefully its a quick repair will check it today, is it fairly easy to take out and replace?

Matt

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[Chesto18]

As above, bet the extra boost has killed your DV valve.

Does it feel less boosty? As in, you can usually feel the boost come on. When my DV valve was torn it felt like it had no boost at all.

Get the Rev D or GFB DV+ with stage 2.

[Mk5matt]

Litterally no boost at all, you can still hear the turbo spooling but nothing comes from it. After the map it sounded like it had a dump valve but now that's gone aswell.

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[AJP]

The intercooler hoses are also susceptible to failing at the connectors as well as the diverter valve. Upping the boost is a quick way of identifying any weak points! Check for oil around the connectors. A little bit is normal but if it's really weeping, investigate further.

Just to add re DVs... a few people have mentioned a couple of issues with the GFB DV+ in that it might sometimes need servicing despite the fact it's meant to be a fit and forget part.

Theoretically the VW revision D valve (piston) can leak a bit of boost due to its design and doesn't necessarily mean it's 'broken'. In practice this may mean the turbo is worked harder to meet requested boost, which aint ideal (heat).

The VW revision G (diaphragm) is IIRC what Nick of R-Tech recommends. I've been running one for a while at decent boost levels and things are spot on.

I've no first hand experience of the rev D or GFB, but thought it was worth mentioning the things I've read. There are so many 'which is the best DV' discussions - I've trawled through most of them - and generally the rev G is as well regarded as any other option, which is why I personally chose it.

Anyway good luck and hopefully you get that air back into the engine where it belongs :)

[ROH ECHT]

You're not boosting enough to worry if you use a DV-d or DV-g. I 5th, 6th, or 7th the DV. You have not had the codes pulled?

I personally wouldn't replace the DV without checking the boost levels with my VCDS...got a friend with OBDII, VCDS, or other? You can replace the DV yes, but what if you then find a cracked brake booster hose or the PCV has failed? Sort of thing that will go through my mind even though I know what it might be.

[Mk5matt]

Had the car jacked up this morning, split diverter valve. New part here tomorrow

Pretty sure its the rev g aswell which i thought were ment to be the better ones.

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[AJP]

Had the car jacked up this morning, split diverter valve. New part here tomorrow

Pretty sure its the rev g aswell which i thought were ment to be the better ones.

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Should be a G on the end of the part number. You'll be back on boost soon

[Chesto18]

Had the car jacked up this morning, split diverter valve. New part here tomorrow

Pretty sure its the rev g aswell which i thought were ment to be the better ones.

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Mine was a G and it was torn to shreds. Car is bog standard.

I replaced with a G which is ok so far, but I think from my own research you have to treat as a serviceable part really. Even on a standard car the Rev G’s only last so long.

If I was running a stage 2 map I’d be going for a piston design, as I’d not want to have to keep replacing the damn thing.

[ROH ECHT]

I hate the diaphragm DV's...would use a piston type if wasn't already using a nearly indestructible Porsche type DV on vacuum for ten years now without issue.

[willni]

I hate the diaphragm DV's...would use a piston type if wasn't already using a nearly indestructible Porsche type DV on vacuum for ten years now without issue.

Is this a kit or did you just research this? There doesn't seem much documented on it.