SuperbTWM

Did you manage to have a peek inside the old engine before you got rid?

A Ctek is not what I would call a trickle charger but they seem to be favoured by dealers and other professionals, I've had the 7 amp one for around 10 years but its not like it gets used every day so not sure I can give it a glowing review but it does what it says on the tin.

If it does go south and you fancy trying a different ECU you can pick them up second hand with the immobiliser disabled which means its plug and play They can be picked up for around £100+ on the famous auction site depending on what engine code you have

Have you changed the DSG thermostat also? This seems to be a common issue with cars not getting up to operating temperature. May or may not be related to your fans running/possible DPF issues though

I have been thinking about buying one of those Chinese diesel heaters to heat my conservatory, havn't yet pulled the trigger but from the countless Youtube video's i've watched I already feel like Ive been tinkering with them. I would like to burn some waste engine oil in some kind of mix as some claim you can, some claim you can't but from what I've seen you either have to filter it (being used diesel egine oil full of soot probably doesn't help things) or be prepared to clean the combustion regularly. Have you run anything 'dirty' through yours? Regarding the E85, I wouldn't put it anywhere near a common rail given that it has managed to wear out a basic solenoid pump

That’s why the answer is to change them!

IMO it’s a daft idea, the charge cooler has to be pretty efficient as it has to handle some very high temperatures coming from the turbo and I feel putting that stuff around that system isn’t going to be good. it could potentially block the cooling rad and effect the electric pump also If you are keeping the car just fix it right.

You know what the Dealers are like, there will be 6mm left and they will try and sell you new ones

The rings of colour around the disc, a mint disc will look uniform like it just came out of the box. obviously it’s a photo and I can’t feel the disc so it might just look worse than it is.

I suppose 5 minutes is technically 300 seconds so you are sort of right 😉 (EA288) 'Post-Start Glowing Post-start glowing helps reduce hydrocarbon emissions and combustion noises during the warm-up phase. For post-start glowing, the switch-on time of the onboard supply voltage is adjusted in the PWM duty cycle to ensure that there is an effective voltage of 4.4 V. Post-start glowing lasts a maximum of 5 minutes after starting the engine or until coolant temperature reaches 24 °C.'

If I had to pay the dealer to change the discs and pads it might make me think twice but I have tried skimping out before only for corrosion to set in soon after or have problems with uneven wear or juddering, especially where the front is concerned, needless to say I replace discs with pads every time to save myself potential problems. I'm sure you could just put pads on and you will probably be fine but I don't like the look of the first photo, looks like the disc has worn unevenly across the surface.

Interesting to hear you have tyre pressure readings, I guess that means VAG have started fitting actual TPMS sensors in each wheel.

The EGR cooler is in the same circuit as the heater matrix so it stands to reason that the silica bag split blocking it up will indeed result in poor heater performance. Not sure why the coolant would go brown unless it has been contaminated by something in the process of having the work done, or maybe the lack of egr coolant flow caused the coolant to become 'burnt', after all its cooling 600+C exhaust gasses at times. Glad you got to the bottom of your woes.

A bit disapointing not to get to the bottom of this but I feel your pain. Maybe the next owner will be along shortly 🤣 Hope you enjoy your S4!

There are 3 coolant pumps on these engines so make sure you clarify which one needs replacing. By heater pump I assume its the electric one which is part of the heater micro circuit, not the mechanically driven one. This is a really easy fix so its worth making sure this is working first and maybe trying to back flush the heater matrix before you go ahead and potentially change the heater matrix for no reason.

Using a dumb charger is fine as long as you don't leave it on the battery for a long period of time, a more modern smart battery charger is a better option. It doesn't even have to be AGM or EFB compatible it just won't charge the battery fully as the fully charged voltages are higher on EFB and AGM than a normal lead acid battery. It is also pretty pointless charging the battery up to 100% anyway as the first thing the car will do is discharge the battery down to 80% to make room for energy recovered by the alternator while braking and when under engine braking (diesels from 2015 ish not sure about petrol models)

or clutch switch. It sounds like this car just needs a good diagnosis to me with somebody that knows what they are doing. If you are getting warning lights they are most certainly some error codes

I hope you have stopped trying to do 80mph since you have had oil pressure issues. First port of call is to get a pressure gauge and find out if its genuine, then you can decide if its a knackered sensor, a blocked pick up pipe, a tired pump (unlikely) or excessive clearances in the engine (also unlikely unless you come back and tell us it knocks a bit and has 300k on the clock) Have you checked the basics like the oil level?

There is non when cold, injects straights away, or should do. This is what prompted me to ask about CTS as if it thinks its warm/hot then there is a minimum speed which may not be reached if the starter or battery is tired.

Never heard of glow plugs helping a DPF regen, if anything they could result in pre ignition of the unburnt fuel that is destined to burn in the DPF which seems counter productive but happy to be proven wrong as always. It is always better to have them operational though as it will sure help the engine's combustion after initial starting in cold weather. Did you have the DPF lights on? if it was that blocked you should of had multiple warning lights

Try unplugging the CTS when you start it outside. This should make the car think its very cold IIRC, this will give maximum glow plug time (not that it should need it) If its still doesn't start under those conditions then there is deffo something weird going on. Is there a custom map on the car? How old is the battery, is it turning over well?

At that mileage you are opening a can of worms, it sound slike you have at the very leak and air leak and an oil leak. Glow plugs will be shot, injectors will be tired, EGR system will all be gunked up, turbo seals are probably a bit leaky if its original as well. It needs a proper going over by a mechanic and maybe you might be abe to eek some more life out of the old girl

I would stick with the 5-30.

When you haven’t got a lot to go on all you can do is go round and check the obvious or get an idea or have a guess and then try and prove it’s not that and move on to the next. last fuel issue I had on a polo 1.4 PD about 10 years ago took me a while to sort. Most mornings it would start and then die instantly and then take a lot of cranking to get going. To cut a long and boring story short I faffed around for weeks trying different things with the lift pump, hoses and filters working my way through the fuel system. I then bought a second hand tandem pump and when I came to fit it the suction hose to the pump came off really easy, it never leaked a drop but it must have been loose enough to suck a load of air in on the first start of the day. A 50p hose clip later and it never failed to start again! Nobody ever has the same fault, but it’s worth checking round at all the fuel hoses, injector connector, sensors, anything you can see just give it a prod or a wiggle, you might just be lucky enough to find something! Good Luck!

My gut says you have a fuel problem, an intermittent lift pump or possibly a loose hose somewhere allowing air to enter the fuel system and air locking the injectors or losing prime, this is causing the seemingly random but mostly when the car has been left a while - hard start issue. having a hard start, then shutting the engine off and plugging the cam sensor back in and having a good start proves nothing. You should have really stopped the engine and tried to start it again without touching anything to prove the fault repeats itself before you then change a variable when fault finding. like I said, it’s a hard diagnosis over the internet but I have a feeling you are barking up the wrong tree.