Tag: twincharged

Living with a Scirocco 1.4 TSI 160 (118kW) – Part 3, Supercharger Bypass Valve (P10A4 Fault)

Sometime last year I was having problems finding a spot in a carpark so ended up sat in the car with it idling for several minutes and when I went to pull away the engine warning light flashed on almost immediately – not something anyone wants to see!

For the rest of the drive the car would mostly work ok at low engine RPM but the engine all but refused to go above approximately 3000rpm which is around the RPM the turbo takes over from the supercharger on this engine and the supercharger is disengaged by its electronic clutch. The curious bit was that at hitting the cut off there was a sudden loss of power at that RPM rather than it staying consistent and just holding an RPM limit suggesting it wasn’t a limp mode as such. My initial suspicion was that the turbo wasn’t spooling up so whether the wastegate was stuck open or something I didn’t know.

Luckily I bought VCDS which is an excellent tool for diagnosing and performing adjustments and if you do a lot of work on VW’s well worth the investment so I hooked that up to see what fault the check engine light was actually reporting and saw the following :

A quick Google of the code P10A4 identifies specific air regulating flap in question but this could also be found by a brief search of the engine bay – there aren’t many flaps in the intake! VW refers to this part as J808.

Image of the TSI160 engine with intake flap highlighted

What this flap actually does is when the supercharger disengages the flap opens providing an unrestricted flow to the intake of the turbo. Obviously if this doesn’t open when the supercharger disengages suddenly the air supply to the engine is closed and you get a massive power loss. You can see what’s going on in the image below which is taken from VW’s manual for this engine – SSP-359. This isn’t a workshop manual but does explain the design and behaviour of this engine in a good level of detail.

There are quite a few guides on how to replace this part such as using the one at workshop-manuals.com . This is an excellent resource but I do recommend using an ad blocker before going there as there are so many ads it’s very annoying otherwise!

My approach to get at the flap was to start at the airbox end and disconnect all the lines going into the intake tract (there are many in all directions so carefully work along it). Eventually once everything is detached you can undo the three long screws which hold the intake pipes on either side tight against the flap and so hold it in place. In my case I ended up detaching the section of pipe after the flap as well so I could lift the whole intake pipe up to get access to the bottom screw nearest the engine as its very awkward to get at otherwise.

Anyway as usual I didn’t want to replace the part if I could avoid it and luckily I found some comments somewhere saying the problem was caused by oil weeping from the intake into the flap unit clogging up the motor so I wondered if it could be cleaned because fundamentally there’s very little that can go wrong inside as they are basically just a motor. Luckily at this point knowing this was likely the problem I figured I couldn’t make it any worse than dead so started trying to work out what was going on.

So looking at the casing of the valve I came to the conclusion there was a simple gearing mechanism inside but based on the space between the clear position of the motor under the curved housing the likelihood was that the gear on the motor itself was small and so I could not explain why there was a significant large area in the housing below it which would likely be a handy cavity with no obvious purpose. The problem being caused by oil makes sense – the motor sits in the bottom of the housing which is underneath the intake pipework so any oil leaking into the housing would pool around the motor. I think the leak is through the spindle bearing for the flap.

So I came up with a plan which may be apparent already because I neglected to take any “before” pictures. I didn’t want to cut the unit open because even though the two halves appeared to be screwed together it looked like the seam had been sealed in some way (presumably part of why oil gets trapped inside) and while nothing appeared to be spring return I really didn’t want to risk it. So I decided to drill a small hole into the extra casing I identified earlier by using the casing as a guide as to where the gear and so end of the motor was. I then carefully drilled a small hole approximate 4mm in the casing and indeed there’s clear space behind this area.

My plan was basically to just flush the inside out with brake cleaner to remove all the oil residue so the hole was just a little large than the straw on the spray can. Sure enough on blasting some into it immediately the predictable brown runoff started pouring out. Another interesting thing happened as well – some residue started to run out of the seam inside the intake passage suggesting this isn’t sealed from the internal workings and in fact the seal on the unit is only on the very outer edge if the housing which may well explain the leaking issue! anyway several passes with brake clean and sloshing it about inside to rinse out as much as possible (I recommend just keep replacing the brake clean until it runs out clear) and it should be ok again hopefully. At this stage you might want to spray a small amount of lithium grease through the hole onto the gears for longevity but if you do just keep it small so you don’t just end up fouling everything with that instead!

Next, make sure the thing is totally clear of brake clean! I held mine under a hot air hand drier for about 10 minute to make it hot enough to drive off all the vapour then left it out in the sun for about half and hour. The last thing you want is a it catching fire!

The final thing I wanted to do is cover up the hole, particularly now knowing the intake wasn’t sealed from the innards. To solve this I tapped the new hole out to M5 and carefully checking the clearance I had behind the cover I put a short button head in place that wouldn’t foul the motor drive gear. Hopefully this also means If I ever have this problem again cleaning it should be easier. You can see the new M5 button head below.

After putting it back into the car I used VCDS to clear the fault code and so reset the engine warning light and took it on a test drive to confirm everything was fine. I think in total this took me about three hours but I was figuring it out as I went so you could probably do it in less.

While this was done during 2020 and so I have been using the car less due to travel limitations and working from home I can confirm that now five months later the car still works well and I have had no further issues following this repair.

Living with a Scirocco 1.4 TSI 160 (118kW) – Part 2, Turbo Replacement

It’s been a little over a year since I posted the introduction blog article on this car and more specifically on the unusual twin charged engine it has. Unsurprisingly over the last year or so I’ve found a few things that need a little work but generally the car has been excellent, needing minimal thought but certainly has some aspects to be aware of for prospective owners to keep the the engine working correctly.

When I bought the car it was a bit lacking power compared to what I was expecting and when accelerated hard in one gear (which due to a seemingly large gap between the supercharger and turbo rev ranges required revving it high) and changed up it would randomly have no power at all. I managed to trace this to a couple problems both related to the turbo wastegate. Firstly the requirement to rev it high was caused by serious wear on the wastegate pivot meaning the wastegate didn’t fully close so the turbo wouldn’t spin up properly. A temporary bodge to get round this is to tighten up the actuator rod to take up the slack but while this sort of helps it actually wears the housing even faster but it can get you by while you wait for a replacement. The second problem of lacking power after a high RPM change was that the wastegate actuator rod was actually bent and touching the turbo housing so it was actually getting temporarily stuck when fully extended so going into the next gear the turbo was basically just dumping the exhaust out the wastegate rather than doing anything useful. So this definitely needed looking at!

First off let me just say I initially looked at the position of the turbo nicely sat at the top front of the engine and thought a couple hours and it’d be done. I was wrong, very wrong! It looks lovely and easily accessible but it just isn’t as easy as it looks for many reasons mostly relating to it not being a turbo mounted to a manifold. the entire exhaust side manifold and turbo are a single unit so you need sufficient clearance to pull the whole unit out.

There it is under the heat shield – looks simple right?

I used various guides to do this swap and generally was in a rush (that didn’t work out so well) so I have very few photos of this but the information is fairly widely available anyway (try searching for guides to the mk6 Golf with the same engine) this is to highlight a few points people may find useful. I suggest referring to workshop manuals for a handy guide with diagrams of each section you need but strongly recommend an ad blocker before you do.

  1. The hard plastic boost pipe which runs from the supercharger to the turbo inlet is retained at the turbo end by a single M6 torx bolt with the threads tapped into the aluminium casting. On the rebuilt unit I bought this thread turned out to be ruined to the point it was impossible to tighten. I suspect this is because undoing the captive fastener during disassembly tries to push a metal sleeve out of the plastic. This is fine in itself but I think it wears the aluminium, similarly tightening it back in will also be hard on it. The reality is the pipe should be pulled back a little at a time as the screw is undone to prevent the load on the threads but this is a bit awkward to achieve as the pipe has very little ‘give’ in it. I strongly recommend checking this before you start – I had to call in a favour because having spent a lot of time swapping the turbo it was rapidly approaching closing time for all the shops to get anything to repair this and without it the car shouldn’t be run. If you’re in any doubt just buy an M6 helicoil kit and put a shiny new insert in place in the aluminium casting because there is only the one screw and if it fails your car will not be happy! Helicoils in softer materials are actually stronger than directly tapping the material the right size because the insert is a stronger material than what it’s going into and because they’re fitted by screwing into a larger thread in the parent material than the desired final thread they have a larger contact surface area in that material.

2. To fully undo all the bolts of the manifold flange you have to undo the alternator mounting bolts and twist it out the way. To do this you have to take off the alternator belt by releasing the tensioner then remove the top mounting bolt for the alternator entirely and slacken the other. This requires removing the engine bay undertrays as well but if you’re doing this job save some time and just pull them all off now. The alternator can then be rotated down and away from the block to get at the bolt. Someone out there might have some creative way of getting at that bolt but I had nothing that would get at it from any angle and couldn’t see any other way if could be done because it’s in a recess with manifold one side, oil filter casting the other and alternator in front of it.

3. Remove the radiator fans. In the picture above you can see how tight this is relative to the turbo and so you need to do this to have enough clearance both to get tools in to undo the manifold nuts and also to remove the the turbo itself from the exhaust studs. Removing these is done from the underside and also involves removal of the pipe between the turbo outlet and intercooler to give sufficient space. You need this removed to change the turbo anyway so it’s no inconvenience.

You’re looking to remove pipe sections 15, 16 and 17 for clearance. Item 11 are two bolts holding the charge pipe to the engine. The radiator sits between the charge cooler and this charge pipe.

The fan module can be removed as a single unit downwards with both fans in place by simply removing the four bolts holding it to the radiator and unplugging it at its electrical connector (item 13 on the bottom edge in the image above).

4. Buy a fitting kit off eBay or somewhere – there are load available but this is the simplest way of making sure you have all the replacement seals and gaskets you might need. Get the most comprehensive one you can find if you can’t easily go to get more parts once this car is apart!

5. The oil drain hose from the turbo is an absolute pig to get at.

The part I’m referring to here is number 12 above and consists of a section of solid pipe at the turbo end with a very short section of hose crimped on. I used a socket on a series of extension bars to get the bolt out of the turbo end but the block end is very awkward to get at because you can’t see it from any angle and the access is tight because the bolt sits virtually under the downpipe. Good luck! When you’re struggling to put it back on after changing the turbo don’t forget the gasket. Also this pipe is apparently common for leaking because the bolt doesn’t get put in sufficiently tightly or the gasket gets damaged during reassembly. I’ve highlighted this below in red.

6. The coolant hard line on top of the turbo needs to be removed which leaves an open rubber hose end. An M8 bolt fits perfectly to block this and stop coolant pouring out over everything so have one to hand before you take it off.

7. Carefully check the boost control hoses – apparently these commonly crack and certainly in my case they were quite degraded around the turbo. You can buy the proper replacement VW part if you wish but it may be cheaper to just order some 5mm vacuum hose and put a run in. In my case I didn’t notice the damage until I started taking it apart and managed to get a random bit from a friend. His wasn’t the common stuff it was thin walled and reinforced so the standard clamps didn’t fit but luckily with some persuasion I managed to fit the thin hose into an offcut of the original one. When combined with a suitable hose clip it’s working fine and has been for ages – that said I do not recommend this option!

Damaged section of hose in red above. The image below shows the hose I replaced marked in red going from the turbo housing back to the boost control solenoid and then the second similar line from the solenoid to the wastegate actuator marked in green.

Unfortunately as I mentioned earlier I didn’t take extensive photos of this replacement but I hope these few points help someone out there!

Good luck!