Polo 9N3 GTI Boost/Turbo issue

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PiRACY
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Polo 9N3 GTI Boost/Turbo issue

Post by PiRACY »

Hi everyone. I was taking my polo for a test drive with its new milltek exhaust yesterday, and during wide open throttle in 4th I suddenly lost turbo boost, almost as if a pipe had perhaps ruptured.

It was running around 21psi peak according to my gauge. Today I've check all the vac lines above the rocker cover, and underneath to check all the new piping and hoses on the Airtec FMIC which has been fine since I installed it 3 months ago.

The only parts of the intercooling system I haven't managed to check are behind the engine. Just wondering if anyone else with this model has had any issues with the IC hoses "6Q0145828C" or "06A145832M" rupturing or popping off? The former is wrapped in a heat shield which you need to cut to remove in order to inspect.

Image

Lastly, does anyone have any other ideas what else may have caused this issue? I installed a fresh N75 valve a few months ago (the original still worked), and I've tried the original N75 again but its still not holding boost. I took it around the street today after all my checks and its the same. I can hear the turbo spooling if I give it a few RPMs but it didn't go over about 4-5 psi.

Any thoughts would be appreciated!
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by Pynoxim »

If you're able to get your hands on VCDS, give it a scan and see what errors are popping up, that will give you a reason as to why you're in limp mode and running on WG pressure.
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Re: Polo 9N3 GTI Boost/Turbo issue

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Pynoxim wrote:If you're able to get your hands on VCDS, give it a scan and see what errors are popping up, that will give you a reason as to why you're in limp mode and running on WG pressure.
Alright, I'll do that in the morning. Is there a cross reference somewhere to let me know what code represents what error?
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by panic-mechanic »

Yes google works fine.
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by PiRACY »

Alright, here we go:

Image

17963 - Charge Pressure: Maximum Limit Exceeded.

Anyone?
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by THANAS »

Fairly self-explanatory, the car is boosting above the specified upper limit. You should log actual and requested boost.
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Re: Polo 9N3 GTI Boost/Turbo issue

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THANAS wrote:Fairly self-explanatory, the car is boosting above the specified upper limit. You should log actual and requested boost.
Hello! How do I go about logging that data? And what would cause it in the first place? It has the APR Stage 2 software.

Sorry, I'm a novice at this. I cleared the 'DTC' codes and took it down the road again. It seems to be trying to boost again, but it just won't hold it. Certainly something is going on with it. I'm running out of DIY options.

I have a feeling its loosing pressure somewhere. Also just removed the Forge DV and checked the o-rings etc. It looked fine and is not that old anyway. I'm also sure the turbo gauge is showing a higher Hg reading than it was prior to the issue occurring.

The new exhaust was bolted on 2 weeks ago (by a 3rd party mechanic due to my mobility issues) and I've only done about 100km on it. I suspect this could be related?

Is it likely either of those two large IC hoses I mentioned previously could be the issue here?
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by Killerwatt »

Where are you locate? We might be able to reccomend someone.

The car would be pretty much undrivable with a boost pipe that popped off so I doubt its that. Is the boost still around 4-5 PSI?

Since you have anothet n75 I would change that first.
Are there no other fault codes that appear?
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by PiRACY »

Killerwatt wrote:Where are you locate? We might be able to reccomend someone.

The car would be pretty much undrivable with a boost pipe that popped off so I doubt its that. Is the boost still around 4-5 PSI?

Since you have anothet n75 I would change that first.
Are there no other fault codes that appear?
Hello there. I'm in Auckland, New Zealand.

I've tried both the original and the new N75, and there is no difference between them. The boost was around 10-15 psi during my last test drive a couple of hours ago, but would decrease if I hold the throttle in position. I'm thinking it could be a split in a pipe as opposed to it completely popping off. I saw no other fault codes.
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by Jueshen »

if boost pipes are not loose and n75 is new it could be the fuse for the N75.
if a boost pipe was off you would hear it very clearly
i had the fuse blow once and the car did not boost above 0.4 bar when the fuse blew.
not too sure which fuse but check one fuse at a time
Ex:
2007 Polo GTI
Eurodyne! 230WHP & 390NM @ KAR 2016 - without OB
2013 Honda Ballade Elegance
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by PiRACY »

Jueshen wrote:if boost pipes are not loose and n75 is new it could be the fuse for the N75.
if a boost pipe was off you would hear it very clearly
i had the fuse blow once and the car did not boost above 0.4 bar when the fuse blew.
not too sure which fuse but check one fuse at a time
Great idea, I'll look into the fuse in the morning.

As for noise, I can't exactly hear much over the sound of the engine and exhaust, but say if there was a split hose somewhere, then is it perhaps possible it will only make some noise when under boost pressure? Could it also explain why I'm getting some boost then loosing it, much like if a balloon had a very very small hole?
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by Jueshen »

check fuse first.
if a pipe came loose or ruptured you would have heard it when you lost boost. if boost was on and the off without any funny sounds then it may not be a leak
only pipes that could have come loose that would affect boost is from turbo to IC from IC to throttle.
could have also come loose at the TIP but that would not affect boost that much most likely fuelling
could be possible that its a small leak but if it was a very small leak the turbo would try compensate and overboost and you should reach correct boost more or less
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by PiRACY »

Can rule out fuses now. Ended up inspecting every single fuse this morning, and nothing was amiss.

I guess the next logical step would be to ask a workshop to hoist the car up and inspect the entire intercooler system, specifically the only two OEM rubber hose parts of the system: hoses 6Q0145828C and 06A145832M; which I can't get to myself. I guess if they could unclamp 6Q0145828C (prime suspect), the heat sheath could be slipped off instead of cutting it up to inspect the quick way. Then when the hose is replaced (good or bad) they could also fit some better clamps.

I appreciate all the advise and suggestions received! If anyone else has any other ideas, please don't hesitate!
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by Pynoxim »

By the way, that pipe with the heat shielding, that's a 2 piece pipe, with an O-Ring that seals the two parts, but I mean, that's not exactly a huge leak, and if that is leaking you'll see quite a bit of oil on it.

Speak to your tuner and have them log it, they can advise you.
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by PiRACY »

Pynoxim wrote:By the way, that pipe with the heat shielding, that's a 2 piece pipe, with an O-Ring that seals the two parts, but I mean, that's not exactly a huge leak, and if that is leaking you'll see quite a bit of oil on it.

Speak to your tuner and have them log it, they can advise you.
Cheers, yes it looks like it has a metal collar built-in that locks into the hardpipe with a Clip AND a clamp...
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by sonic-mike »

Please can you send me the rest of that diagram you posted
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by PiRACY »

sonic-mike wrote: Mon Apr 16, 2018 9:01 pm Please can you send me the rest of that diagram you posted
Hi, late reply sorry, but I think that was the entire image of those parts. Found it on oemepc dot com I think.
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by PiRACY »

For the record: I resolved this whole issue not long after my last post..... Bought another new GERMAN made N75 valve, and hey presto. I think the first new one was possibly a counterfeit, and the original must have been faulty to.
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Re: Polo 9N3 GTI Boost/Turbo issue

Post by sonic-mike »

Who can please help me check for boost leaks?? Currently in pretoria for the day
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