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General => The garage => Topic started by: danyo on 21 April 2012, 19:02

Title: mk4 gti anniversary problems
Post by: danyo on 21 April 2012, 19:02
Hi Guys,

i need some advice! i purchased a golf gti anniversary just over a year ago, and had nothing but problems!

the symptoms:

- poor cold start up (misfiring, shuddering etc)
- poor fuel economy (lucky to get 23mpg on motorway and 16 around town)
- loss of power (almost feels like there is no turbo. sometimes it's fine)

the car has been remapped and at one point was running fine so i know how quick it can be, but hasn't been like that for a while.

items replaced already:

- mas airflow meter
- thermostat
- temp sensor
- all coil-packs
- had throttle body cleaned and realigned

after all of this i still have the same problem. every time i get it plugged into diagnostics's it comes up with the same error the thermostat.

i am really stuck and wondered if anyone has had the same problem and managed to sort it?

Cheers, Dan

Title: Re: mk4 gti anniversary problems
Post by: barrym381 on 21 April 2012, 19:07
coul try another thermo was it from the dealer ?
Title: Re: mk4 gti anniversary problems
Post by: danyo on 21 April 2012, 19:15
yes straight from vw
Title: Re: mk4 gti anniversary problems
Post by: barrym381 on 21 April 2012, 19:35
did you test the thermo before puttin it in
Title: Re: mk4 gti anniversary problems
Post by: wsmith on 21 April 2012, 20:06
i had the same with mine and also put all the new parts on like you than found out that i had two vacuum pipes split ,mine was the one that comes from the top of the engine like a Y shape , the one behind the inlet it was making the car run rich and thats why it had low mpg and juddering, thats what i was told but since having new pipes fitted its all fixed .
Title: Re: mk4 gti anniversary problems
Post by: danyo on 21 April 2012, 23:10
yes i also had one of those vacuum pipes replaced that was located underneath the manifold as it has completely disintegrated. it ran fine for a month or so but then started to happen again. had the same pipes checked and they seem all ok!
Title: Re: mk4 gti anniversary problems
Post by: barrym381 on 21 April 2012, 23:16
maybe a diffrent pipe this time were are you located maybe some1 near you can help  :smiley:
Title: Re: mk4 gti anniversary problems
Post by: danyo on 22 April 2012, 01:00
im in a place called redditch, just south of birmingham
Title: Re: mk4 gti anniversary problems
Post by: barrym381 on 22 April 2012, 01:08
http://www.golfgtiforum.co.uk/index.php?topic=197918.0
have a look in ther see if any1 is near you maybe they can help some decent ppl on here
Title: Re: mk4 gti anniversary problems
Post by: danyo on 22 April 2012, 15:54
i have a mate who works at vw, even the mechanics there don't know what the problem is!
Title: Re: mk4 gti anniversary problems
Post by: topher on 22 April 2012, 15:57
is the misfiring/shuddering on cold start-ups only lasting around 30 seconds?
Title: Re: mk4 gti anniversary problems
Post by: danyo on 22 April 2012, 16:00
yea that's right! have you had the same problem?
Title: Re: mk4 gti anniversary problems
Post by: topher on 22 April 2012, 16:07
nah my cars never go wrong :grin: :lipsrsealed:

it would suggest something is going wrong with the secondary air injection system (pump on the front of the engine that blows air behind the valves to help burn off the additional cold start fuel and warm the cat up). The common fault is a leaky pump because the rivets that hold it together break up and fall out.. however with your other symptoms it is quite possible there is an issue with the solenoid (N112) that activates the pump or the vacuum lines to the solenoid.
Title: Re: mk4 gti anniversary problems
Post by: danyo on 22 April 2012, 16:12
when you say leaky pump....what would leak out exactly? oil? water?
Title: Re: mk4 gti anniversary problems
Post by: topher on 22 April 2012, 16:15
air :cool: but dont get too fixated on the pump itself the vac lines that control the solenoid that switches the pump on are in the bundle of mess under the inlet manifold and if they're plumbed in incorrectly or leaking you effectively have a boost leak which can cause your lack of power and poor fuel economy.

oh and just to add, the fault code that comes up relating to the thermostat (error in mapped cooling system?) can also be caused by a knackered coolant temperature sensor, which can also lead to power/economy issues.
Title: Re: mk4 gti anniversary problems
Post by: danyo on 22 April 2012, 16:58
so the chances are the bits i have already changed, something out of them could be faulty!
Title: Re: mk4 gti anniversary problems
Post by: KeithyGTI on 06 May 2012, 08:20
I.....
Title: Re: mk4 gti anniversary problems
Post by: danyo on 16 June 2012, 08:56
Hi Mate,

i believe it was a faulty thermostat that was fitted. car runs a lot better now and has cleared the engine code. although it does run a little rough on startup...