URGENT oil pressure stop engine

[pudding]

Yeah. 91 does 1 camshaft, and 92 does the other. I assume 91 is inlet camshaft @Dan_FR ? I think the n205 valve affects the inlet camshaft timing somehow?

Yep.  The cam adjuster has 3 oil passages in it.  Advance, 'neutral' and retard.  The job of the N205 is to divert the oil into the relevant passage when commanded by the ECU.

There is no exhaust cam timing on this engine.  The later TSI has adjustment on both.

Weird really as you normally have some kind of exhaust timing for EGR purposes.

Anyway, get measuring!  If 91 shows 28 degs for actual and requested, that ain't the cause of the misfire I'm afraid.  Replace the valve anyway as it's not well if it's being fault coded.

[rich83]

I still have no idea how that cam adjuster works.... witchcraft

[Pesky jones]

Yeah. 91 does 1 camshaft, and 92 does the other. I assume 91 is inlet camshaft @Dan_FR ? I think the n205 valve affects the inlet camshaft timing somehow?

Yep.  The cam adjuster has 3 oil passages in it.  Advance, 'neutral' and retard.  The job of the N205 is to divert the oil into the relevant passage when commanded by the ECU.

There is no exhaust cam timing on this engine.  The later TSI has adjustment on both.

Weird really as you normally have some kind of exhaust timing for EGR purposes.

Anyway, get measuring!  If 91 shows 28 degs for actual and requested, that ain't the cause of the misfire I'm afraid.  Replace the valve anyway as it's not well if it's being fault coded.

Ok. Well you say im afraid but surely the timing being correct woukd be a good thing? Then its misfiring because of something else, hopefully simpler. Coils or spaek plugs eg?

But yeah I will measure tonight and fit the n205 tomorrow and measure again

[Dan_FR]

It wouldn't be plugs or coils, it would be valve damage and pulling the head off.

Let's not forget that this hasn't been ruled out yet and is still a very real possibility given the car is misfiring and running badly at idle

[Pesky jones]

It wouldn't be plugs or coils, it would be valve damage and pulling the head off.

Let's not forget that this hasn't been ruled out yet and is still a very real possibility given the car is misfiring and running badly at idle

Oh, so the compression test didn't rule that out? If the timing is correct then could there still be a possibility of valve damage or is the only way to rule out valve damage to take the head off?

[Dan_FR]

Personally I think there will be damage and struggle to see how there couldn't be after trying to start the car with a snapped chain, not ot mention everything else. But I am a bit of a pessimist, so.....

Rule everything else out first. Hopefully the N205 will sort it....

[Pesky jones]

Personally I think there will be damage and struggle to see how there couldn't be after trying to start the car with a snapped chain, not ot mention everything else. But I am a bit of a pessimist, so.....

Rule everything else out first. Hopefully the N205 will sort it....

Oh I thought the compression test had ruled that out  as 150psi across all four cylinders so I thought that the cylinder and valve arrangement would have been correct with no leaks.

I will try and fix the other issues first.

[Pesky jones]

Also I forgot to add another video. This was when I first turned it on last night. It gets worse as it goes on, you can here the noise start to ramp up at around 1 minute. At 1.50 I pick the camera up and move around.

[pudding]

The same compression reading across all 4 cylinders doesn't really suggest valve damage to me, but they are low.  Should be around 190psi on a new or very healthy used engine.  Consistency across all 4 is the most important thing though.

You'd expect at least 1 cylinder to be significantly down on the others if there was valve damage.  Even bending an intake valve a couple of degrees off centre is enough to drop huge amounts of compression. 

I still have no idea how that cam adjuster works.... witchcraft

It's pretty easy to understand how it works when you've got it all in bits tbh.   This is no 'VTEC yo' thing though.  All it does is adjust the valve open and close times, not the lift and lobe duration like the VTEC does.  VTEC is done for power.  This system is done for efficiency.

All you need to picture in your mind is when oil is fed into a chamber inside the adjuster, it twists relative to the (fixed) exhaust cam and because the inlet and exhaust sprockets are connected with a chain, if the adjuster on the exhaust cam moves 10 degrees, the chain therefore pulls the intake cam round 10 degrees.   Feed oil into the other chamber and the adjuster moves the opposite way.   The tensioner in the middle keeps the chain taught during the retard and advance movements.

Maybe this cut-away drawing might explain better!

[Pesky jones]

The same compression reading across all 4 cylinders doesn't really suggest valve damage to me, but they are low.  Should be around 190psi on a new or very healthy used engine.  Consistency across all 4 is the most important thing though.

You'd expect at least 1 cylinder to be significantly down on the others if there was valve damage.  Even bending an intake valve a couple of degrees off centre is enough to drop huge amounts of compression. 

Right, how did you know it should be around 190? I thought our compression ratio was 10:1 so atmospheric pressure at 14.7 x 10 = 147, pretty much perfect for my 150psi reading.

I might do another compression test once the n205 is fitted.

Still don't know what fuse to remove for the HPFP, last time I just removed a couple I thought might be related

[ady-gti]

To me it sounds like the engine is running on low oil pressure. After it's started it takes over 15 seconds for the low rumble to stop, only for a noise to start again about 20 seconds later. It could be lots of things but I think more damage has been done to it that you think as - sorry to say.. :(

[rich83]

All you need to picture in your mind is when oil is fed into a chamber inside the adjuster, it twists relative to the (fixed) exhaust cam and because the inlet and exhaust sprockets are connected with a chain, if the adjuster on the exhaust cam moves 10 degrees, the chain therefore pulls the intake cam round 10 degrees.   Feed oil into the other chamber and the adjuster moves the opposite way.   The tensioner in the middle keeps the chain taught during the retard and advance movements.

Maybe this cut-away drawing might explain better!

I get it... thanks.

[pudding]

The same compression reading across all 4 cylinders doesn't really suggest valve damage to me, but they are low.  Should be around 190psi on a new or very healthy used engine.  Consistency across all 4 is the most important thing though.

You'd expect at least 1 cylinder to be significantly down on the others if there was valve damage.  Even bending an intake valve a couple of degrees off centre is enough to drop huge amounts of compression. 

Right, how did you know it should be around 190? I thought our compression ratio was 10:1 so atmospheric pressure at 14.7 x 10 = 147, pretty much perfect for my 150psi reading.

I might do another compression test once the n205 is fitted.

Still don't know what fuse to remove for the HPFP, last time I just removed a couple I thought might be related

Just numbers I've seen others quote on forums, for example, last but one post - http://www.golfmkv.com/forums/showthread.php?t=121672

I'm not sure the math works in that way tbh.  Even R32s with 11.5 compression x 14.5 = 166psi, but they always measure around 190psi on a gauge.

[doylebros]

Pesky - you said you run it with the airbox/engine cover - on that last video it shows differently. Build it up as it should be with no missing bolts from any areas and all connectors plugged in don't worry about the N205.
If there's any vacuum leaks you get rough running and running it as you have, you'll get the problems your showing.
So keep it simple, put back all the bits and redo another video and do your VCDS checks for the timing values.

[Pesky jones]

I think I said it I run it a couple of times with and without the airbox, ive got a few videos of each time..the first video is with airbox. I have more video if there worth uploading?

Do you mean remove valve cover and cam chain chain cover and build it back up from there, just making sure 110% this time?

Ill check timing tonight, so hopefully I dont have to remove the chain and tensioner. Ill also check misfires, clear fault codes and re scan and then report back.

I have already ordered the n205 as well as the vaccum pump bolts (1 currently missing) and the cam chain cover gasket...

Do you know the fuse to pull for the hpfp @doylebros ? Just incase I pulled the wrong one