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Mk5 General Area / Re: Mk5 GTi stage 1 fuel pressure problems
« Last post by ZoliWorks on Yesterday at 06:15:12 pm »
The injectors themselves have a general lifetime of no more than 100k km. They'll work more than this, but under 100k is when they still operate in factory params. Then again, you cant trust sh*t nowadays cause i installed 4 brand new oem injectors in mine and one failed after a month...

Injectors generally fail by leaking or getting stuck open/closed. They are engineered with very small tolerances so once they get dirty inside, that's the end of them. you also cant really clean petrol injectors because of mechanical wear. To get a matching set of 4 injectors that all spray in the same pattern and the same volume, you need to refurb about 14 injectors at least.

Another thing that fails about them is the filter at the top. It literally disintegrate and get's sucked into the injector. OEM filters last about 60k km or less so most people opt for mesh baskets instead.



Now regarding misfires, it could be caused by many things. My misfires under WOT were caused by a sticking injector while my current misfires at idle are caused by mechanical wear inside the engine. Specifically, my camshafts are rusted and pitted. During idle, cyl 3 misfires 90% of them time.

Other likely causes are spark plugs, ignition coils, valves that arent sealing properly, carbon buildup on the valves and in the intake, faulty pcv system, faulty maf, or a vacuum leak. Plus billion other things...

My advice is, as long as it runs and doesnt have issues during WOT, dont try to fix it lol
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Mk5 General Area / Re: Mk5 GTi stage 1 fuel pressure problems
« Last post by Lassebongo on Yesterday at 06:00:06 pm »
Alright good to know! Also found that cylinder 4 misfires, not much but still. How long does the injectors last you think? Recently replaced all the seals on the injectors but it didn't fix the misfires, so I'm suspecting they are on their way out as well.
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Mk5 General Area / Re: Mk5 GTi stage 1 fuel pressure problems
« Last post by ZoliWorks on Yesterday at 01:03:33 pm »
100k is about the expected lifetime of these pumps tbh. They will last more but can break at any moment.

95% is basically dead. IIRC even under WOT it should be around 65 max. I think I deleted my logs but I dont think I've ever seen it go above 70 and that was when when I was pushing it for 370hp
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Mk5 General Area / Re: Back in a MK5 GTi, anything to urgently do?
« Last post by Bassman1974 on August 29, 2025, 09:42:39 pm »
Its fair to say that there are many 2.0 tfsi's bombing around with high mileage on the original chains. The 400k plus GTI on here has never had the chain and associated components replaced.

That said, mine is sitting at a wild -17°. I've an original camshaft position sensor inbound. Obviously it's not a true value or it would be running as lovely as it does for it's 155k.

It checks how much the cam phaser is adjusting to keep the engine in time.  As the cam chain stretches over time the phaser takes up more slack to a point where it can't and you start to get hard starts and/or chain rattle noises at start up etc.  You can see how many degrees off 0 it is making an adjustment.  Up to 3 is usually fine, but then 4 to 6 you will be getting a lot of noises (consider sorting it very soon) , then above 6 you are a ticking time bomb (change ASAP if you want to keep the car)...........when checked on a warmed up engine.

The chain starts to show its age from about 80k to 100k depending on how well the engine has been maintained and driven.  The phaser also wears out and struggles to keep oil pressure to maintain the adjustment.  I changed my chain and tensioner 8 years ago but not the phaser and the chain had to be changed again recently due to the worn phaser prematurely wearing the chain (it was on -3.0 degrees from 0 after 20k miles and 8 years)..........replaced it all now
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Mk5 General Area / Re: Mk5 GTi stage 1 fuel pressure problems
« Last post by Lassebongo on August 29, 2025, 09:18:53 pm »
Yea as I feared I ordered a new pump and controller. The new pump will have a newer revision, 1t0 DB i think it was, same with the controller. It's weird though because its a low milage for its age. 130k
Yea I did log the duty cycle att some point, lost the file, it did max out at 95% if I remember correctly.
Thanks for the insight, I'll post the results after the swap!
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Mk5 General Area / Re: Mk5 GTi stage 1 fuel pressure problems
« Last post by ZoliWorks on August 29, 2025, 03:46:20 pm »
Holy, yeah look at your low-pressure side, that's basically dead. I'd say in-tank pump, controller or maybe the filter but unlikely. Your low pressure side is basically starving your engine completely. It should never really drop under 4.5 bar on full WOT.



Try logging the in-tank pump duty cycle as well. I forgot the exact VCDS param for it. Auxiliary fuel pump or electric fuel pump? something like that.

If you're going to replace it, there are a few threads here with people and the pumps they used.
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Mk5 General Area / Re: Back in a MK5 GTi, anything to urgently do?
« Last post by mjmallia on August 29, 2025, 02:27:58 pm »
It checks how much the cam phaser is adjusting to keep the engine in time.  As the cam chain stretches over time the phaser takes up more slack to a point where it can't and you start to get hard starts and/or chain rattle noises at start up etc.  You can see how many degrees off 0 it is making an adjustment.  Up to 3 is usually fine, but then 4 to 6 you will be getting a lot of noises (consider sorting it very soon) , then above 6 you are a ticking time bomb (change ASAP if you want to keep the car)...........when checked on a warmed up engine.

The chain starts to show its age from about 80k to 100k depending on how well the engine has been maintained and driven.  The phaser also wears out and struggles to keep oil pressure to maintain the adjustment.  I changed my chain and tensioner 8 years ago but not the phaser and the chain had to be changed again recently due to the worn phaser prematurely wearing the chain (it was on -3.0 degrees from 0 after 20k miles and 8 years)..........replaced it all now
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Mk5 General Area / Re: Back in a MK5 GTi, anything to urgently do?
« Last post by darren4 on August 29, 2025, 02:04:44 pm »
Might as well check the cam Phase position - VCDS, Engine > Block 93, should be near or close to 0KW

Whats this checking for, sorry if thats a silly question
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Mk5 General Area / Re: Headliner Repair Trim Piece
« Last post by Bassman1974 on August 29, 2025, 01:25:48 pm »
If you think the rear is brutal, you should see the price of the front. Pretty sure I paid about £120 for mine.

It fairly cured the sagging though.
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Mk5 General Area / Headliner Repair Trim Piece
« Last post by Jons1001 on August 29, 2025, 12:06:09 pm »
My headliner is sagging around the rear interior light. I found these online but nowhere seems to have stock anymore. Also messaged the manufacturer but no response.



Does anyone know where i might be able to get hold of one? The price of £70 is a joke though for a bit of plastic, would be great if we could get hold of the specs so we could 3d print them!

Thanks

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