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Author Topic: GTI with lack of boost. Help  (Read 5912 times)

Offline B1NCC 1.8T

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GTI with lack of boost. Help
« on: February 14, 2016, 12:34:25 pm »
I have a mk5 GTI giving me boost/ lack of power problems.

It blew the turbo a few months ago (didn't blow up and throw pieces everywhere tho- just kinda seized the properller) I replaced turbo with genuine KO3 not a cheap dung thing from eBay. It came with a brand new N75 valve and modified diverter valve.
The car also has a new PVC valve at some point recently. 
The fuel pump tappet thing is in good condition too. Fuel pressure figures within spec

Currently its not holding boost.  It has a boost gauge fitted and when out on road it boosts to 25psi but quickly drops off to 10psi but holds at 10.
Car has a huge alloy intercooler with silicone boost hoses , 3" decat and a full stainless exhaust. Also im told car is remapped. It's also a DSG.

I've taken all the pipes off and checked for leaks etc also checked the rubber sealing rings between the other boost hoses.

No real faults in VCDS either. Once it's came up with the EVAP fault. Which they all seem to have lol. Also it once came up with a MAF fault.

Wondering if anyone can help me any further. Maybe I've missed something
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Offline bacillus

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Re: GTI with lack of boost. Help
« Reply #1 on: February 14, 2016, 01:12:57 pm »
Looked at the DV to check for torn diaphragm?
On a ko3 the dv is bolted on to the turbo housing.
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Offline B1NCC 1.8T

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Re: GTI with lack of boost. Help
« Reply #2 on: February 14, 2016, 01:37:06 pm »
Diverter valve Is brand new modified piston type
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Offline Bo!

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Re: GTI with lack of boost. Help
« Reply #3 on: February 14, 2016, 06:04:43 pm »
Is it possible the intercooler has a small split somewhere .?
I had same issue on my old Leon boost would spike up and tail off to a certain point. had a boost test carried out at a specialist and it turned out to be a split in the intercooler .
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Offline B1NCC 1.8T

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Re: GTI with lack of boost. Help
« Reply #4 on: February 14, 2016, 06:15:24 pm »
Quote from: Bo! on February 14, 2016, 06:04:43 pm
Is it possible the intercooler has a small split somewhere .?
I had same issue on my old Leon boost would spike up and tail off to a certain point. had a boost test carried out at a specialist and it turned out to be a split in the intercooler .

Thanks for the reply mate. I was beginning to think the fancy intercooler might have a leak. But there's a lot of ideas flying about in my head just with this car lol.
I will get a smoke test done on intercooler.
Thanks mate.
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Offline r5gtt

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Re: GTI with lack of boost. Help
« Reply #5 on: February 14, 2016, 06:33:38 pm »
Hi what was it like before the Turbo seized?. was throttle response perfect or was it lacking boost?
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Toek162

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Re: GTI with lack of boost. Help
« Reply #6 on: February 14, 2016, 08:10:17 pm »
Any codes
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Offline B1NCC 1.8T

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Re: GTI with lack of boost. Help
« Reply #7 on: February 29, 2016, 06:41:36 pm »
Back on this one.
Did a smoke test on the whole intake/boost system and ruled out any boost leaks.
Intercooler is spot on (unforunalty)

Still no fault codes

Also stripped down the fuel pump and check the pump tappet for wear. Both the cam and the tappet are mint condition.

I never drove the car before the turbo failed.
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Offline ROH ECHT

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Re: GTI with lack of boost. Help
« Reply #8 on: March 01, 2016, 02:33:38 am »
My guess is there isn't enough preload on the actuator rod...if the actuator diaphragm itself and the N75 are new...the DV mod is fine...no boost leaks are detected...and finally, there can be no leaks in any of the vacuum lines and the lines at the N75 and actuator diaphragm must be properly clamped.

Given that all the leak tests have been completed and the list of new bits mentioned...I would definitely turn the nuts on the actuator rod a couple of extra turns(2mm) towards the actuator diaphragm...away from the internal WG valve.

With engine cooled and the heat shield for the right-side axle boot removed:
Remove clip #1...back off the #2 nut three full turns (approx. 3mm) towards the actuator diaphragm...snug the #3 knurled nut toward #2 nut and tighten #2 with your 10mm wrench...replace clip #1 and retest.
« Last Edit: March 02, 2016, 02:24:21 am by ROH ECHT »
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K04 PLAY...K04 turbo/S3 INJ. & FMIC/FORGE FMTC, TB hose, & WG actuator/GIAC's H.O. K04 & DSG TUNES/AWE DV/NEUSPEED P-FLO,TURBO OUTLET & TB pipe/AUTOTECH hpfp/BSH Eng.&Trans Mounts/H&R ARB's/Whiteline Performance springs & W.A.L.K./ECS stage-3 BBK/BILSTEIN B8's...ZOOM'DIS...GIAC K04 tune-2007 Volkswagen GTI: 12.823 @ 112.050 MPH__Voting for my Dragtimes link: http://www.dragtimes.com/Volkswagen-GTI-Timeslip-25700.html?r=1

Offline Beej

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Re: GTI with lack of boost. Help
« Reply #9 on: April 10, 2016, 10:00:13 am »
Sorry to jump into someone else's thread, but got a wee question.

I tried adjusting mine yesterday (lying under car on drive) got the clip off, but loosened, but could not get the knurled nut bit to budge, then to add insult to injury, spent the best part of an hour trying to replace the clip with no joy. Made sure the nut was firmly snugged back up and left it, as I need the car.

Any tips for getting this knurled nut to spin?
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Offline r5gtt

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Re: GTI with lack of boost. Help
« Reply #10 on: April 28, 2016, 09:51:47 pm »
@Beej

Plenty of WD40 or a blow torch of the hand held kind if you have one. I do lol
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Offline Beej

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Re: GTI with lack of boost. Help
« Reply #11 on: April 29, 2016, 07:46:41 am »
@r5gtt

It's extremely tight even trying to get a decent set of grips up there and still be able to see what you are doing never mind a small blow lamp, but I can see where you are coming from.

I am going to attempt to have a go from above, as I am not left handed, and from underneath, it favours the left handers out there!
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Offline r5gtt

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Re: GTI with lack of boost. Help
« Reply #12 on: April 29, 2016, 06:09:42 pm »
@Beej Maybe the thing turns the opposite way and you're actually tightening it?  :thinking: just a thought remembering you need to undo the 13mm nut first.  :signLOL:
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Offline Beej

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Re: GTI with lack of boost. Help
« Reply #13 on: April 29, 2016, 06:12:08 pm »
The thought had crossed my mind, but then I realized that I had already loosened the nut, so the knurled nut must spin the same way....

I am thinking its either seized or just extremely tight, so I will give it a go from above, see if I can access it.

In the meantime, I ordered a dv+ today
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Offline r5gtt

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Re: GTI with lack of boost. Help
« Reply #14 on: April 29, 2016, 06:15:57 pm »
You'll love having the gfb dv +  :happy2:

Not saying you haven't but try turning the thinner nut thing as that may help. or its way too tight because of the heat it has to handle. or maybe give it a go when it's hot but now I'm being silly  :stupid:
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