MK5 Golf GTI
All Things Mk5 => Mk5 General Area => Topic started by: FlashGTI on August 21, 2022, 08:59:29 pm
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Hi all,
I am still struggling with an issue whereas when Boosting it will boost hard but as it gets over around 1.1-1.2 bar it drops straight off to about 0.2 and you can hear a pressure release. The car will keep accelerating but just no boost.
I have tried to attach a logged VCDS file but have no idea how to do it!
I have tried to put a screen shot in here and have in the first column put a rough marker for when the boost drops under acceleration and I am wondering if there is an issue with the fuel rail or does this look normal?
Any assistance would be appreciated...its driving me nuts :stupid: and at the moment I feel more like getting rid of the car than fixing it
Thanks in advance for any assistance
(https://i.postimg.cc/GpPN0hLN/Golf-issue.jpg) (https://postimg.cc/v1BXfy6L)
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If you give more details about the car, it will be bigger the chance someone to help you. Is it stock, some remap, any mods?
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It’s had the following done:
Stage 1 remap just done (had this issue on old map too)
Oversized Ram air
R8 coil packs
S3 intercooler
HPFP VIS internals
New turbo just fitted (had this issue on the old turbo too)
New n75 valve
3” down pipe
200 cell sports cat
3” miltek cat back
New PCV
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How come you've had a stage 1 map despite having all the hardware for a stage2+ map fitted?
Anyway sounds a bit like my old issue, couldn't locate it and could hear boost escaping when at peak boost to the point it would almost not be able to accelerate anymore, it was the rocker cover gasket in the end.
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I did have it stage 2 mapped, but was advised that that the guy who done it was not very good and people have had problems. So I got it put back so I could start a base line and remove some of the questions!
My rocker gasket has been replaced recently including the whole plastic top part, that didn’t make a difference as had the issue before and still have it now.
2 things I have noticed yesterday, the pipe from the intercooler to the front of the engine has some wear in it from the fan rubbing against it. Doesn’t look to have gone all the way through but wondering if it could be enough that at peak pressure it escapes.
Other point is that there is 1 screw missing on the left side of the PCV valve holding it to the rocker cover. Although PCV seems fine and not leaking when on idle
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I'm not seeing a DV in the list of parts. Has that been replaced since getting this problem?
Missing PCV screws and fans chopping through boost pipes..... seriously? Have you recently acquired the car? Sounds like it's been bodged by previous owners and you need to get it back to a proper baseline before investigating the boost issues.
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Yeah I have a new Reg G fitted to it, that hasn’t made a difference.
Im not sure when the screw went missing, when I got the car it had a cheap catch can and I put back on the PCV and screw was there then. I think maybe was lost when the garage down the rocker gasket. But still the issue was there before that time.
I must admit I hadn’t noticed the pipe when I bought the car! Seems I bought a bit of a dog, but loads done on it now with the cam belt, timing chain, and new turbo etc so feel like I am too far in to stop now! Although it is so tempting to sell it at the moment
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I know exactly what you mean on both counts!
Is the fan assembly fixed to the radiator tightly? I can't see how the fans would rub on that pipe unless they were flapping around aimlessly, or the boost pipe wasn't attached to the block/head and also wobbling about the place for fun! If you can hear boost escaping, that's a start I suppose. Maybe check all the one-way valves in the brake servo pipework and also the evap canister pipes.