2007 MKV GTI - Weird Issues - Turbo / Engine Related

Hi Guys,

Hope you all good ? Need some advice please. I have a weird issue for a while now on my MKV GTI.

Background - She is a K04 , S3 Injector, Neuspeed Cooler and Nuespeed Intake, Walbro 450 Mod Low Pressure Pump, Autotech HPFP upgraded Internals - FR&R Stage 2+ baby.

So - Issue only recently started, they told me its the LPFP, so replaced that with a Walbro but still persisted, was a litte better though. Need to log again to see if the pressure dropping issue has been solved

It dropped lpfp pressure on 4000 to 6000 RPM below 2 Bar.

Now she runs much better, but dies out after hard acceleration and sudden stop - Revs drop below 500rpm and then she dies. Have to restart again.

Other issues also possibly related - On idle the boost gauge shows -20 vacuum as per normal, but then bounces between -20 and -16 (This tells me Vacuum Leak??)

Also if she is hot and after some spirited driving, there is sometimes a type of Rev hang when changing gears ? Also doesn't then boost full 27 odd PSI as she should but only 15 (Intermittent)

All of the above, my common sense says Vacuum leak, where the actuator doesn't then get enough vacuum to open up and free the boost ? Or do I understand it wrong ?

*When driving at highway speed or slower, you can hear a sort of faint metal on metal noise ticking (not the brakes, from motor side) - Then boost and tap off accelerate, then for a second or so delayed, there is a squeak / tweet noise (faint) as if there is air / boost leaking out a very tiny hole ? Not a normal boost leak sound but something else.

Any advice will be appreciated

Following has been checked / replaced :

New NGK BKR 7EIX (x4)
New Walbro 450 modded in OEM basket
OEM Controller (And Spare one) With both it does the same
Spulen PCV Block off Kit
New Cam Follower
New HPFP
Fuel Pressure Regulator checked (On top of the HPFP)
New 6.6 Bar Fuel Filter
New Oil
Actuator checked for play (nothing)
Boost Piping checked and tightend

I would check your intercooler piping out of the turbo on passenger side. If you see any oil on the pipe coming from a connection that's your problem had the same thing happen to me car stalls after a pull. I'm trying Ultra Black RTV to fix the seal. Idk if it works perfect just did that this weekend I need to stress test it before I go stage 1 again

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SavageGTI said:

I would check your intercooler piping out of the turbo on passenger side. If you see any oil on the pipe coming from a connection that's your problem had the same thing happen to me car stalls after a pull. I'm trying Ultra Black RTV to fix the seal. Idk if it works perfect just did that this weekend I need to stress test it before I go stage 1 again

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Yes I have Oil in that pipe - You think its because of the oil that the car stalls ?

Must I clean out the oil, then tighten the clamps again ? In SA turbo is on driver side. So will check it. Or is there a spot somewhere from the turbo it leaks oil ?

But how does this affect the power loss issue I have ?

Thanks

Oil is normal it's blow by from piston rings or from pcv a catch can could help but not necessary.

I would clean the pipe connections and hook them up again. Your loss of power is because the compressed air isn't making it into your engine, it's leaking out the pipe (if oil drips it's not air tight). This is a vaccume leak.

I believe it stalls because your ecu is expecting a certain amt. of air but is not getting it and has too much fuel. When I had this problem I would restart my car and it would backfire too which led me to think extra fuel being burned in my exhaust I've got a 3in catless TBE. With vaccume leaks all kinds of weird things happen 500rpm idle stalling out ect.

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SavageGTI said:

Oil is normal it's blow by from piston rings or from pcv a catch can could help but not necessary.

I would clean the pipe connections and hook them up again. Your loss of power is because the compressed air isn't making it into your engine, it's leaking out the pipe (if oil drips it's not air tight). This is a vaccume leak.

I believe it stalls because your ecu is expecting a certain amt. of air but is not getting it and has too much fuel. When I had this problem I would restart my car and it would backfire too which led me to think extra fuel being burned in my exhaust I've got a 3in catless TBE. With vaccume leaks all kinds of weird things happen 500rpm idle stalling out ect.

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Makes sense - Not leaking out of my piping at least - I think its still a vacuum and possibly the rear PCV breather hose, will check it out

The rest has been checked, cleaned and tightened recently

Issue is the power loss comes and goes - Will happen now and then. Some suggested I must check the MAF Sensor, unplug and see if it runs better ?

Yeah you could try to unplug maf and see that's probably more for idle. There's still a vacuum leak somewhere

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