MK5 Golf GTI
All Things Mk5 => How to Guides / Troubleshooting => Topic started by: cmdrfire on December 24, 2009, 10:41:52 pm
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'lo all,
I am here beseeching your wisdom.
Those of you who saw my car at the Surrey Rolling Road saw that it was a bit broken, turbo apparently only boosting 0.2bars on the run, 230 horsepowers suggesting that 20 horses are having a break. I kind of knew it was a bit broken already from butt-dyno.
So why is the turbo not boosting? This is the question, and it is perplexing - because the turbo does boost sometimes, I see it (very rarely!) reach 1.1bar peak on my boost gauge under certain (not yet identified) conditions, most other times it does hover around 200-ish mbar.
So: I can be reasonably certain there's no boost leak, as there's no lack of boost at all times; so intercooler piping et al is probably OK.
I do have a forge DV - I'm reasonably certain this is functioning nominally, as improper functioning would result in a CEL if I'm not mistaken (anyone with a more informed view please comment). However it is possible that VW have fiddled with it following my accident in 08 and I haven't had an opportunity to properly investigate it.
The other option is that my software (I'm running Superchips at the mo, but lacking a Bluefin handset) is acting screwy. My money's on this one as it's the neatest explanation of why it still boosts correctly sometimes but not other times; but why would the software be operating incorrectly? A few (mostly airbag IIRC) controllers were changed following my accident, could this be a causative issue? Worth trying other software on there just to see what happens?
If anyone's got any other thoughts, please do chime in, as I wanna get this fixed now, it's bugging me a lot. I'm also toying with the idea of just giving the car to someone for a couple of days to just fix as I've been hella busy of late. Any recommendations on that front as well?
Thanks in advance.
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For a one stop shop I wouldn't go any further than JKM.
As to your problem - do you have VCDS or access?
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For a one stop shop I wouldn't go any further than JKM.
As to your problem - do you have VCDS or access?
I was thinking about JKM. I'll drop them an email about it and see if I can get some other stuff done at the same time (WALK, engine mounts, and so forth).
VCDS, I neither have nor do I have ready access to, though it would probably help significantly in diagnosing the problem.
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I would regrease your forge dv first. This happens to me now and again if I leave too long between greasing. I guess it sticks open allowing boost pressure past. Did mine a few days ago because of this.
Edit. I never get a CEL because of this.
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^
That's a very good thought and I may have a go at that tomorrow if it's not too cold (yes, I'm a wimp).
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You still made 230bhp so it's not losing serious boost pressure! Ur car is quite high mileage so I'd be looking at the turbo area, like actuator, exhaust housing, wategate port, manifold etc for a wee crack somewhere. Check the vacuum line for the forge dv too. Does ur defi boost gauge take the pressure from the forge thingy??
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I think a couple of people with the earlier cars have had cracks form in the turbo housing.
You could also try fitting a new OEM DV in place of the forge.
All of this would be easier if you had some diagnostic software so as I an says perhaps passing it over to Jim & Keith for a couple of hours would be better.
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Thanks Lee & Stu. The defi gauge is taking pressure from the forge multitap thing.
Cracks on the turbo housing are a bit worrying, Robin had that problem didn't he?
And whilst I'm here, other people without catch can have seen milky oily stuff on the oil cap in cold weather right?
(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Ffarm3.static.flickr.com%2F2753%2F4213496503_d3ae61a25c_b.jpg&hash=6aad427acdaab4596b86912cf72126757f90dcc3)
oh: and happy Christmas!
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I would say the was reasonably normal, especially if you do short trips.
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errr thats normally a sign of head gasket gone isn't it...mayo like crap on oil cap?
i topped my oil up earlier and it was NOT like that (or any previous cars), and I do plenty of short trips
sign of water mixing with oil Neo...not good.
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errr thats normally a sign of head gasket gone isn't it...mayo like crap on oil cap?
i topped my oil up earlier and it was NOT like that (or any previous cars), and I do plenty of short trips
sign of water mixing with oil Neo...not good.
I've seen pics of US GTIs with the same issue, so I wasn't terribly concerned.
Also, failed head gasket results in no compression in some cylinders... and I'm pretty certain I'd have noticed that :P
The head gasket failure stuff tends to be more "fluffy" because of the coolant mix IIRC.
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:grin: well u r the engineer and i'm just a bean counter :signLOL:
but the head gasket / mayo theory is something i've heard since i started driving!
maybe it is just condensation from current weather...and the car needs a nice long run to clear out some crap.
How's the coolant level looking (saying that mine's just below the min mark on that too! :surprised: )
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:grin: well u r the engineer and i'm just a bean counter :signLOL:
but the head gasket / mayo theory is something i've heard since i started driving!
maybe it is just condensation from current weather...and the car needs a nice long run to clear out some crap.
How's the coolant level looking (saying that mine's just below the min mark on that too! :surprised: )
Haven't checked tbh, though I've been meaning to.
My car ate a lot of coolant last year, when the weather was much milder (to the point where the coolant warning light came on!). This year doesn't seem to be an issue, though I better double check tomorrow.
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The solenoid valve, that the vaccuum pipes go to, could be knackered, mine was playing up along with my DV giving me 150bhp at Superchips.
They're about £45+VAT and its located in the most annoying place, on the chassis leg, right by the cambelt cover.
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....
I think this thread is showing that it could be one of any number of things - The trouble with a relatively minor problem is that they are often more tedious to diagnose.
Like others here, I have absolutely no hesitation whatsoever in recommending you contact JKM. They are also a Superchips agent and so can cover that possibility too. Reading both my boost leak issue thread and illyun's issues thread should put you in no doubt just how helpful and good JKM are re the 2.0T FSI platform.
Keep us posted and best of luck with it all.