1.4 tsi twincharged low compression

Sm007

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My friend is doing engine work on another 1.4 tsi so I decided to borrow his hpfp to see if it cures my issue, but once the car warms up it loses all its pressure it shows 3.5 bar fuel pressure on vcds but when it is running fine it shows 50 bar can't figure out what's causing this
 

Sm007

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Quite possible, I have even seen them with the fuel lines the wrong way around.
I've double checked the fuel lines and they seem to be in the correct place, the charcoal canister is connected to the second fuel line and the fuel line in the picture is the main one that goes to the hpfp which is connected to the first fuel line, is there any way I can check on vcds if the intank pump is working correctly
 

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Crasher

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The fuel lines are easy to reverse on the top of the fuel delivery unit under the back seat, you need a suitable diagnostic system to check it properly but the pump should cycle when the door is opened or the engine turned over so take care with the lines off.

This is Golf 7 but it is similar

https://flic.kr/p/2kHbmEJ
 

Sm007

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Jan 2, 2021
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Luton
The fuel lines are easy to reverse on the top of the fuel delivery unit under the back seat, you need a suitable diagnostic system to check it properly but the pump should cycle when the door is opened or the engine turned over so take care with the lines off.

This is Golf 7 but it is similar

https://flic.kr/p/2kHbmEJ
Yes the pump makes noise when door is opened and you can hear it while engine is started but it also makes a weird noise sometimes
 

Sm007

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ITS FIXED :) the intank fuel pump was faulty as it kept on making some weird noises, the new fuel pump has a different sound.
took it for a test drive and everything seems really good.
Thank you again @Crasher for your help appreciate it
 

Sm007

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I've done around 2k miles with this car and seems like the turbo doesn't kick in sometimes after 3.5k rpm and today after a motorway journey I had the check engine light on, the code is shown below, would you know what I can check
 

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Sm007

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Sticking wastegate spindle, eventually it will strip the gears in the actuator.
Hi crasher so funny thing is I didn't notice that the actuator is disconnected from the waste gate when I was rebuilding the engine, so I refitted the rod into place but when I apply vacuum to the turbo actuator it doesn't move at all but I can pull it by hand 🤔
 

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Crasher

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It is likely the spindle is seized, you need to have the turbo rebuilt or exchanged as the damage to the casting can render the unit scrap, Midland Turbo are excellent at rebuilding these, they do all ours.
 

Sm007

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It is likely the spindle is seized, you need to have the turbo rebuilt or exchanged as the damage to the casting can render the unit scrap, Midland Turbo are excellent at rebuilding these, they do all ours.
Hi I've checked the spindle it seems fine but when checking the n75 valve there doesn't seem to be any vacuum
 

Crasher

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Sorry I had the wrong engine in my head, it's a CAVD isn't it? If you look at the system plumbing you can see the N75 valve is operated by charge air system boost pressure, not post throttle body manifold vacuum.
 

Sm007

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Sorry I had the wrong engine in my head, it's a CAVD isn't it? If you look at the system plumbing you can see the N75 valve is operated by charge air system boost pressure, not post throttle body manifold vacuum.
Yeah its CAVD engine, I'll have a look today but isn't the n75 on this engine supposed to have constant vacuum, when I checked there doesn't seem to be any vacuum, and near the back of the engine around manifold I can hear some kind of hiss noise
 

Sm007

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If you look at the pipework you can see it is pressure operated, vacuum operation is usually only used on TDI versions with a VNT turbo.
That makes sense now, but what could be causing the p2263 code, low down power is fine but when I'm in 5th or 6th gear and I try going over 3.5 k RPM seems like the turbo doesn't kick in
 
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