White puff of smoke at start only.. need your inputs !

[RUM4MO]

My logic/answer to that is that over a longer period in time, the fuel rail pressure will drop as a weeping injector passes the petrol and eventually there will come a point where the pressure has dropped down to a point where the weeping injector is no longer weeping - and so the leaked fuel will evaporate leaving next to no excess fuel in the cylinder when you cold start after an overnight stop.

None of this might be relevant in your case, or it just might be, just getting rid of the easy reasons for puffs of smoke so that you can move onto more serious ones if the root cause lies elsewhere.

 

[AVCUPRA290]

My logic/answer to that is that over a longer period in time, the fuel rail pressure will drop as a weeping injector passes the petrol and eventually there will come a point where the pressure has dropped down to a point where the weeping injector is no longer weeping - and so the leaked fuel will evaporate leaving next to no excess fuel in the cylinder when you cold start after an overnight stop.

None of this might be relevant in your case, or it just might be, just getting rid of the easy reasons for puffs of smoke so that you can move onto more serious ones if the root cause lies elsewhere.

I thought you might be interested in seeing some photos of the inside of my cylinders

spark plug of cylinder 1. I did 2 videos of the cylinders with an in between at idle until oil reaches 50 degrees C. I did clean the spark plug which was already oily the first time and this is the 2nd time I took it off.

There was oil in each cylinder (some photos of cylinders 1 and 4 with a previous idle and after) I only took videos of the others but




and up in the cylinder the valves :



would like your feedbacks, but it looks like oil to me, leaking from the valves (seems to be coming more from the exhaust valves but might just be dripping this way with the inclination of the engine or just carbon deposit related to unburned oil exiting this way)

The car is full stock and has 87000km on it, bought at Seat dealership and always serviced there. I’m hoping to fulfill a manufacturer claim in order to get them to pay for it..

 

[RUM4MO]

Very good resolution/clarity you got with your borescope, I bought a used Ring RBS300, but so far I've not been able to get good pictures from it, I'm guessing that you got the pictures of the valve by fitting a 45 degree mirror, I should try harder to get good pictures of the inside of all our family car engines now - before I have any need to use it in earnest!

Edit:- my only reason for keep pushing the "injector weeping" theory is, any oil getting into there will stay there until the engine is next started, so I'd expect regular puffs of smoke when restarting after 4 hours, 24 hours, 48 hours etc etc. Petrol on the other hand will evaporate and as I described lessen its flow into the cylinder as time goes on between engine starts.

Also, as I said, I have not yet managed to get good piston top pictures and so can't comment on what is showing in these pictures even although it does look like a liquid, ie oil.

 

[AVCUPRA290]

Very good resolution/clarity you got with your borescope, I bought a used Ring RBS300, but so far I've not been able to get good pictures from it, I'm guessing that you got the pictures of the valve by fitting a 45 degree mirror, I should try harder to get good pictures of the inside of all our family car engines now - before I have any need to use it in earnest!

Edit:- my only reason for keep pushing the "injector weeping" theory is, any oil getting into there will stay there until the engine is next started, so I'd expect regular puffs of smoke when restarting after 4 hours, 24 hours, 48 hours etc etc. Petrol on the other hand will evaporate and as I described lessen its flow into the cylinder as time goes on between engine starts.

Also, as I said, I have not yet managed to get good piston top pictures and so can't comment on what is showing in these pictures even although it does look like a liquid, ie oil.

Yeah I was quite happy with the quality and no mirror needed it’s a 180• rotative cam so you can see backwards when you’re in the chamber.
I also still don’t understand why I don’t have any puff after 12h but among the pictures you’ve seen I did two different sessions : first one with the car cold for 24h, the second one maybe an hour later after letting it idle until oil temp reached 50 degrees.
So it does seems to be oil down there since it was still there after 24h but I didn’t get any smoke when I started up right after these images.

I also have videos if you’re interested but I think they are too heavy to put in there.

 

[The-Cupra]

No no smoke when the car is totally cold at least less likely since I started really monitoring it :

- if I restart the car immediately after stopping : no smoke
- smoke happens when parking for 30min to 4h (will monitor for 5-6-7-8h to see when I don’t have any)
- once, while parked on a slope I did have smoke after 45min parked and then shut off the car and tried again 3min later and got smoke

Yeah I was quite happy with the quality and no mirror needed it’s a 180• rotative cam so you can see backwards when you’re in the chamber.
I also still don’t understand why I don’t have any puff after 12h but among the pictures you’ve seen I did two different sessions : first one with the car cold for 24h, the second one maybe an hour later after letting it idle until oil temp reached 50 degrees.
So it does seems to be oil down there since it was still there after 24h but I didn’t get any smoke when I started up right after these images.

I also have videos if you’re interested but I think they are too heavy to put in there.

If you have oil in the cylinders like this your valve cover is leaking and you need may need to replace it, only if it gets bad. On this engine there is not a valve cover gasket they use an anaerobic sealant. The anaerobic sealant VW uses is green, if you look around the engine you may be able to see some around the edges of the valve cover.

Its not a big deal unless it gets bad. If you look into it on the likes of the Golf R. Its quite common. Not something you need to rush in for doing unless you start to get oil on the plugs and misfiring. Might be worth considering getting done with the timing chain to save yourself money. If seat will do it under warranty that's another option... its not exactly a cheap job. Also id want someone decent to do the work as its very possible it could leak again if not done right.

 

[AVCUPRA290]

If you have oil in the cylinders like this your valve cover is leaking and you need may need to replace it, only if it gets bad. On this engine there is not a valve cover gasket they use an anaerobic sealant. The anaerobic sealant VW uses is green, if you look around the engine you may be able to see some around the edges of the valve cover.

Its not a big deal unless it gets bad. If you look into it on the likes of the Golf R. Its quite common. Not something you need to rush in for doing unless you start to get oil on the plugs and misfiring. Might be worth considering getting done with the timing chain to save yourself money. If seat will do it under warranty that's another option... its not exactly a cheap job. Also id want someone decent to do the work as its very possible it could leak again if not done right.

How could I tell if it’s valve or valve cover ? Is it because I have oil in all cylinders ?
I did have some green particles on the edges of the wells.
Should I expect other sign of valve cover leaking around the engine bay ?

I do have some oil on spark plugs, especially on one but no misfiring for now.

Is it some normal wear or something might have caused this ?

It is probably not abnormal or not related but I’ve noticed some vacuum at the oil cap when idling. I know it is supposed to be under negative pressure but don’t know how much is normal : See here
I did replace the PCV but same vac

Sorry, lot of questions

 

[RUM4MO]

I'm not convinced that a leaking valve chest cover would be contributing to this puff of smoke at start up, oil leaking out of that area and into the "holes" that the spark plugs are in could end up causing misfires, but I'd doubt if any of that oil will end up getting down into the combustion areas.

So I'd suggest not adding this option in to the mix right now.

Edit:- the vacuum or sucking in of ambient air when you remove the oil filler cap does seem to be normal, ie it is getting limited by the PCV bits, so okay.

 

[AVCUPRA290]

I'm not convinced that a leaking valve chest cover would be contributing to this puff of smoke at start up, oil leaking out of that area and into the "holes" that the spark plugs are in could end up causing misfires, but I'd doubt if any of that oil will end up getting down into the combustion areas.

So I'd suggest not adding this option in to the mix right now.

Edit:- the vacuum or sucking in of ambient air when you remove the oil filler cap does seem to be normal, ie it is getting limited by the PCV bits, so okay.

I didn’t think of it at first but if it can indeed lead to oil getting into the combustion chamber it might add up with some of the things I’ve observed and be more plausible with the mileage of the car :

1 - oil on the top of the spark plug and near electrod


2 - green pieces of sealant in the combustion chambers and around wells



3 - few oil leaks starting at the top timing chain cover which I replaced and camshaft sensors + at the outside of the engine at the valve cover gasket



(also my oil does smell petrol)

but .. after thinking about it in every ways I’m not sure oil could go into cylinders through spark holes.. I would have wells full of oil and it would still not get in the combustion chamber this way

 

[RUM4MO]

Yes, but when the spark plug is tightened down into its position, any engine oil dropping down on to the threads of the spark plug, will get stopped from getting down into the combustion chamber by the spark plug sealing washer - otherwise, combustion gases would also get back up and out of the combustion chamber and very quickly burn the spark plug and the threaded spark plug hole - and that would be a whole lot more trouble/damage to repair.

Oil smelling of petrol might just be due to how the car is getting used - or it might be due to weeping injector/injectors.

Edit:- getting all your petrol injectors checked for weeping/flow/spray pattern might be a smart thing to do.

 

[The-Cupra]

I also agree with ram4m0. though your cover is leaking. I would leave this issue.... it could be weeping injectors. Iv just watched a video that had an issue with an weeping injector. Check it out here:-

 

[AVCUPRA290]

Hi and thanks for your answers !

Do you still think I need to check injectors with every cylinder with oil in it ?
Seems to be valve stem seals and the repair are way too expensive at seat (3.3k€) and the warranty does not cover it I already asked them. My plan is to keep searching for an indie willing to do it but so far no one. Asking manufacturer won’t work I think.
Next service is Wednesday I will replace spark plugs and put 5w40 instead of 0w30 and see how it goes.
I’d love to share the videos but they are too heavy here are some previews :

Cylinder 1 cold :


Cylinder 1 1h after idle :



Cylinder 2 cold :



cylinder 3 :

Cylinder 3 valves :


cylinder 4 cold :

 

[AVCUPRA290]

cylinder 4 1h after idle :

 

[AVCUPRA290]

Hi guys,

I will try to dig in the « weeping injector » possibility because if you look at the pictures above you will see that between pictures of cold cylinders and hot cylinders you have the same amount of black deposit on the piston head (oil ? Liquid ? Solid ?) however, after taking the cold cylinder videos I did start the car and I had no smoke. It makes me wonder why wouldn’t have any smoke when I see that ? Maybe the smoke isn’t related to these deposits.
As mentioned one day I did have strong petrol smell in cylinder 1.

I’m trying to figure out how to test the injectors without remove them :
- I have a bi injection system. The direct injection rail is not accessible without taking off the intake manifold, but the indirect injection can be removed (on the top of the manifold). However I think I need to replace every seals of every injectors I take off.
- Will I be able to detect a leak (even if a small one) by monitoring the rail pressure when ignition on engine off ? I’ve read some test one with engine cold with a target pressure to reach. The same test with engine warm, the pressure will double with the heat. It should double within 5 minutes before starting to drop. If not it means an injector is leaking.
- I didn’t figure out how to depressurized the rails yet. I mean I could take off the pressure pipe coming from the HPFP but might be risky and spitting a lot of gas everywhere. I wonder if taking off the vacuum hose from vacuum pump could help not maintaining the pressure.
- I could at least check the indirect injection rail by taking it off
..

also I don’t have any Codes of fuel rail pressure or misfires..

 

[RUM4MO]

It is risky just "cracking loose" the main high pressure feed into the HP fuel rail - but if you are able to do it safely, then that is a simple way to drop the fuel rail pressure back down to probably below where any faulty injectors will leak, you would need to use a cloth to "contain and absorb" all the spraying fuel.

 

[AVCUPRA290]

So I tried to monitor fuel rail pressure today.

Don’t know what are the target values for my engine but wanted to check if the pressure does rise after engine stopped and ignition on (temperature must more than double the pressure if not rising it could mean there is a leak).

I’ve first monitored the pressure while driving, nothing really surprising (even if I’m no expert in the matter). Pressure did reach 237 bars when idling at a red light.

When back at home I’ve let the car idle the car for a while and pressure was going high around 120-140 bars and then I heard some kind of release valve opened and pressure was released, went back to 44 bars.


2h later I decided to check the spark plugs for petrol smell. They were dry and no strong smell on any cylinders.
I put back the cam in the cylinders and.. surprise bone dry ! No more black liquid on piston heads.
And I had no smoke when starting it up. I usually do have smoke after 2h sitting.
I tried to check fuel pressure with sparks and coils out, was steady 6 bars.

Did another drive to get the car to working temperature and monitor the fuel pressure again :
When I stopped the car the pressure was around 56 bars.
Pressure went up after stopping with the heat and reached 11700kpa within 20min after stop

With a top at 11720kpa around 22min.
It started to slowly go down after 25min.
After 30min 11330kpa.

After 1 hour 7470kpa


Started it up and had smoke.

I noticed that when I let it idle for long enough pressure is steady around 44 bars.
Meaning while cooling down the pressure will reach around 90 bars top.
But if I stop the car too soon the pressure will be higher and then will go higher when cooling.

=> might have a really small leak at high pressure level explaining why I didn’t have smoke after 2h sitting but starting with a steady 4400kpa but I did have some after one hour with a starting pressure around 50-60 bars ?

I will drive the car and park it while pressure is not back to 44bars and take off the plugs during cool down when pressure is around 90-100-110 bars to make sure.
I’m running out of explanations.

Small note :
I had a resonator delete on the car. Which I took off Thursday night. I went for a compression test Friday morning and had smoke at startup afterwards. The same day did not notice any smoke after a long drive and 7h stop. The next day I also had smoke after a 1h stop.
Today after 2h sitting no smoke and cylinders dry. Second try one hour after a drive : I had smoke
Does a resonator delete can be related in anyway ? If it does how ? (Counter pressure ? Condensation? Exhaust gas flow ?)
The fact that I still have smoke without it let me think it is not related but who knows. Might be related to the black liquid deposit found in the cylinders..

Also I’ve put injector cleaner in the tank I’ve finished this morning. So filled up the tank again this morning. The black liquid deposit I’ve found into the cylinders might been related to this cleaner ? Now that I don’t have cleaner in fuel anymore it might have gone and fuel might leave no trace ?

 

[AVCUPRA290]

So I tried to monitor fuel rail pressure today.

Don’t know what are the target values for my engine but wanted to check if the pressure does rise after engine stopped and ignition on (temperature must more than double the pressure if not rising it could mean there is a leak).

I’ve first monitored the pressure while driving, nothing really surprising (even if I’m no expert in the matter). Pressure did reach 237 bars when idling at a red light.
View attachment 41884
When back at home I’ve let the car idle the car for a while and pressure was going high around 120-140 bars and then I heard some kind of release valve opened and pressure was released, went back to 44 bars.
View attachment 41885

2h later I decided to check the spark plugs for petrol smell. They were dry and no strong smell on any cylinders.
I put back the cam in the cylinders and.. surprise bone dry ! No more black liquid on piston heads.
And I had no smoke when starting it up. I usually do have smoke after 2h sitting.
I tried to check fuel pressure with sparks and coils out, was steady 6 bars.
View attachment 41886 View attachment 41887 View attachment 41888 View attachment 41889 View attachment 41890
Did another drive to get the car to working temperature and monitor the fuel pressure again :
When I stopped the car the pressure was around 56 bars.
Pressure went up after stopping with the heat and reached 11700kpa within 20min after stop
View attachment 41891
With a top at 11720kpa around 22min.
It started to slowly go down after 25min.
After 30min 11330kpa.
View attachment 41892
After 1 hour 7470kpa
View attachment 41893

Started it up and had smoke.

I noticed that when I let it idle for long enough pressure is steady around 44 bars.
Meaning while cooling down the pressure will reach around 90 bars top.
But if I stop the car too soon the pressure will be higher and then will go higher when cooling.

=> might have a really small leak at high pressure level explaining why I didn’t have smoke after 2h sitting but starting with a steady 4400kpa but I did have some after one hour with a starting pressure around 50-60 bars ?

I will drive the car and park it while pressure is not back to 44bars and take off the plugs during cool down when pressure is around 90-100-110 bars to make sure.
I’m running out of explanations.

Small note :
I had a resonator delete on the car. Which I took off Thursday night. I went for a compression test Friday morning and had smoke at startup afterwards. The same day did not notice any smoke after a long drive and 7h stop. The next day I also had smoke after a 1h stop.
Today after 2h sitting no smoke and cylinders dry. Second try one hour after a drive : I had smoke
Does a resonator delete can be related in anyway ? If it does how ? (Counter pressure ? Condensation? Exhaust gas flow ?)
The fact that I still have smoke without it let me think it is not related but who knows. Might be related to the black liquid deposit found in the cylinders..

Also I’ve put injector cleaner in the tank I’ve finished this morning. So filled up the tank again this morning. The black liquid deposit I’ve found into the cylinders might been related to this cleaner ? Now that I don’t have cleaner in fuel anymore it might have gone and fuel might leave no trace ?

I did try again tonight cause it’s bothering me.
i stopped the car with around 80bars.
By the time I take off coils and spark plugs I had 164 bars in the rail pressure. With the cam I saw that every cylinders were dry except for the 3rd (when you start from the right of the engine when you face it) and I saw this :
It was brown on one side

And more like wet but not colored on the other

it smelled petrol but not specifically stronger than other wells and spark was dry..
I saw smoke when I started the car afterwards.

What do you think ?

 

[RUM4MO]

You would really need to "collect" some of that stuff that you find in a cylinder, and try to work out if it was more petrol than engine oil washed off into a small volume of petrol.
How to do that? - you would need to vacuum it out - and then examine it and then leave to see if it evaporated leaving just a small deposit of oil, of if it basically just remained as some black stuff, the first would indicate that it was weeping fuel, the second would indicate that it was engine oil.
This is where just trying a few things ends up giving you a few different results - but is what you have as results by doing this much different to that that a car that was known never to give a puff of smoke after a warmish start.

Maybe this "investigation" should be closed down - very annoying to give up or give in, trust me I know this! Once you have an idea in your head, it can be very difficult to ignore it.

Finding out what a proper engine workshop would do to "collapse" the HP fuel rail pressure would be a good plan if you are to continue this investigation, as doing that maybe 50 times and finding no smoke at warmish starting should be enough to give you a good feeling that it is due to fuel weeping into the combustion chambers after a warm/hot engine switch off.

Do you know if there is any built in mechanism to control HP fuel pressure AND return excess fuel to the fuel tank, in a bid to avoid the fuel in HP fuel rail getting too hot under some engine running conditions, it does sound like, from what you have discovered, that shortly after engine STOP, there is a mechanism to significantly drop the HP fuel rail pressure - this makes a lot of sense as why hold the HP fuel rail at running pressures when the engine is stopped, also there will be a lot of "heat soak" feeding back into the HP fuel rail and that is why the fuel pressure is rising after the engine has been switched off - initially. So, another possibility, if there is an excess fuel return circuit that also has a "dump valve", is this working at all times that it is meant to?

Sorry for feeding you with new possibilities!!

 

[AVCUPRA290]

You would really need to "collect" some of that stuff that you find in a cylinder, and try to work out if it was more petrol than engine oil washed off into a small volume of petrol.
How to do that? - you would need to vacuum it out - and then examine it and then leave to see if it evaporated leaving just a small deposit of oil, of if it basically just remained as some black stuff, the first would indicate that it was weeping fuel, the second would indicate that it was engine oil.
This is where just trying a few things ends up giving you a few different results - but is what you have as results by doing this much different to that that a car that was known never to give a puff of smoke after a warmish start.

Maybe this "investigation" should be closed down - very annoying to give up or give in, trust me I know this! Once you have an idea in your head, it can be very difficult to ignore it.

Finding out what a proper engine workshop would do to "collapse" the HP fuel rail pressure would be a good plan if you are to continue this investigation, as doing that maybe 50 times and finding no smoke at warmish starting should be enough to give you a good feeling that it is due to fuel weeping into the combustion chambers after a warm/hot engine switch off.

Do you know if there is any built in mechanism to control HP fuel pressure AND return excess fuel to the fuel tank, in a bid to avoid the fuel in HP fuel rail getting too hot under some engine running conditions, it does sound like, from what you have discovered, that shortly after engine STOP, there is a mechanism to significantly drop the HP fuel rail pressure - this makes a lot of sense as why hold the HP fuel rail at running pressures when the engine is stopped, also there will be a lot of "heat soak" feeding back into the HP fuel rail and that is why the fuel pressure is rising after the engine has been switched off - initially. So, another possibility, if there is an excess fuel return circuit that also has a "dump valve", is this working at all times that it is meant to?

Sorry for feeding you with new possibilities!!

No problem, the issue is not that big for now so the point is to understand it.
From what I’ve discovered the pressure release valve located on top of the HPFP did work twice (from what I’ve noticed), while idling with engine ON. Never heard it while engine off and I did not see pressure reducing drastically after switching off like it did when I heard the valve. (Since this is all electronically controlled im guessing it should throw a code for any issue)

To explain the previous pictures I’ve shown you (ie black liquid deposit in 4 cylinders and then the cylinder 3 with oil & petrol) I’ve searched how injection system works on my 2L tsi :
Bi-injection system with a direct injection rail underneath manifold directly spraying into chambers that is the high pressure rail and it is the main injection system, it is used under loads.
The second system is a lower pression system located on top of the manifold and is used at lower rpm and idle. It is mainly a way of cleaning valves and carbon deposits from there. From what I understand, it doesn’t spray fuel but it places droplets within the intake manifold and they are pushed in the chambers with the air being sucked in. The injection occurs at Low dead center (LDC) so when the piston is going down.

Note that I’ve used injectors cleaner in my last tank, that’s when I’ve noticed the black liquid deposits. It could be related to this cleaner which probably has cleaned the intake manifold when being dropped during indirect injection process. Which can explain why now that I refueled the tank the chambers are dry.

Also, the PCV system reinjects combustion vapors within the combustion chambers (under load it goes through the air intake & turbo, and when vacuum is higher it goes straight to manifold).

Finally mi oil is getting thinner since the oil change is scheduled Wednesday so might be more subject to vapors creation..

My question :
- could it be « not abnormal » for the fuel coming from indirect injection to be a bit dirty with the oil residue from vapors recycling since it goes to the same path within the manifold ?

- since cylinder 3 seemed to be going to LDC when I looked at it could it be possible the petrol had been injected (indirect) and thus not burned yet since I’ve turned the car off ?

- hence could it be not abnormal to see smoke on startups sometimes caused by blow by gas within the manifold + indirect injection making that little puff of smoke ? Since the indirect system is designed to clean the manifold and the valves it could indeed be doing his job. Thus it would happen more likely when the car is not completely cold cause vapors would still be there or an accumulation would be above the valves in the manifold (liquid state) Whereas after a full night those vapors would have formed the classic carbon deposit onto the valves.

What are you thoughts ?
Do you think I still need to have my injectors tested because I shouldn’t have petrol injected into the chambers when I stop the engine so I might have one that keeps dripping a bit after turning the engine off ?
would it make sense that when I’ve checked the cylinders after a 2h stops they were totally dry ?
Am I being too much for keeping digging this whereas maybe nothing is wrong ? (No oil consumption, no gas consumption, no codes, no loss of powers, no leaks..)

(the black liquid deposit wasn’t the cause of the smoke since I had it before and after making the car idle and I did not have smoke at startup since the car was sitting for 24h already)

 

[AVCUPRA290]

No problem, the issue is not that big for now so the point is to understand it.
From what I’ve discovered the pressure release valve located on top of the HPFP did work twice (from what I’ve noticed), while idling with engine ON. Never heard it while engine off and I did not see pressure reducing drastically after switching off like it did when I heard the valve. (Since this is all electronically controlled im guessing it should throw a code for any issue)

To explain the previous pictures I’ve shown you (ie black liquid deposit in 4 cylinders and then the cylinder 3 with oil & petrol) I’ve searched how injection system works on my 2L tsi :
Bi-injection system with a direct injection rail underneath manifold directly spraying into chambers that is the high pressure rail and it is the main injection system, it is used under loads.
The second system is a lower pression system located on top of the manifold and is used at lower rpm and idle. It is mainly a way of cleaning valves and carbon deposits from there. From what I understand, it doesn’t spray fuel but it places droplets within the intake manifold and they are pushed in the chambers with the air being sucked in. The injection occurs at Low dead center (LDC) so when the piston is going down.

Note that I’ve used injectors cleaner in my last tank, that’s when I’ve noticed the black liquid deposits. It could be related to this cleaner which probably has cleaned the intake manifold when being dropped during indirect injection process. Which can explain why now that I refueled the tank the chambers are dry.

Also, the PCV system reinjects combustion vapors within the combustion chambers (under load it goes through the air intake & turbo, and when vacuum is higher it goes straight to manifold).

Finally mi oil is getting thinner since the oil change is scheduled Wednesday so might be more subject to vapors creation..

My question :
- could it be « not abnormal » for the fuel coming from indirect injection to be a bit dirty with the oil residue from vapors recycling since it goes to the same path within the manifold ?

- since cylinder 3 seemed to be going to LDC when I looked at it could it be possible the petrol had been injected (indirect) and thus not burned yet since I’ve turned the car off ?

- hence could it be not abnormal to see smoke on startups sometimes caused by blow by gas within the manifold + indirect injection making that little puff of smoke ? Since the indirect system is designed to clean the manifold and the valves it could indeed be doing his job. Thus it would happen more likely when the car is not completely cold cause vapors would still be there or an accumulation would be above the valves in the manifold (liquid state) Whereas after a full night those vapors would have formed the classic carbon deposit onto the valves.

What are you thoughts ?
Do you think I still need to have my injectors tested because I shouldn’t have petrol injected into the chambers when I stop the engine so I might have one that keeps dripping a bit after turning the engine off ?
would it make sense that when I’ve checked the cylinders after a 2h stops they were totally dry ?
Am I being too much for keeping digging this whereas maybe nothing is wrong ? (No oil consumption, no gas consumption, no codes, no loss of powers, no leaks..)

(the black liquid deposit wasn’t the cause of the smoke since I had it before and after making the car idle and I did not have smoke at startup since the car was sitting for 24h already)

Small update, I’ve tried to check my theory :

Here is the turbo inlet after starting up :

Here is the turbo inlet after 20min idling :


You can see that even if the air flow is going from the intake to the PCV some oil seems to get there, the PCV valve is supposed to be partially closed (I think).
I think it is the culprit of the smoke at startup because what you see in here is only a small part of what is redirecting within the manifold at idle or when engine braking. When under loads, vapors are going straight in the inlet.

As my PCV is new I assume it is functioning correctly.. I have suction at oil cap, a small vacuum at intake hose, steady idle around 700-720 rpm, no codes..nothing surprising.

When I’ve first saw the smoke I did see one time a bit more oil in there :


However when I took of the old PCV the diaphragm looked in perfect state.

to go further I went filming inside the intake manifold.

Here you can see cylinder 2 intake valves from above, and the corresponding indirect injector


Here you have intake valves from cylinder 3 with indirect injector



You’ll tell me what you think but from my point of view valves look really clean, too clean to diagnose bad valve stem seals. You do have some black on the cylinder 3 valve if you look closely enough on the first picture but it doesn’t seem to be enough to be leaking and causing smoke.
(we do not see well enough the cylinder 1 valves sorry but they were even cleaner).
We can also see that below the injector the manifold is really clean, a bit wet around but not right under the injector, to me it means it is probably not leaking and the wet is the petrol residue that has not been sucked in during combustion.
It also leads me to think that the black deposit I had in cylinders was coming from the manifold because of the injector cleaning dripping in and cleaning the manifold.
So I’d say there is nothing wrong I could fine with certitude after everything I’ve looked up..

 

[RUM4MO]

I'm sure that what you are finding, ie the HP fuel pressure rail staying at a very high pressure after warmed engine is OFF is not what is meant to happen, neither is the puff of smoke at warm engine start, but, I'd think that it would cost a lot of time and money to to sort this out, also most workshops would not consider this to be an issue that is worth investigating - ie they would not be able to guarantee to resolve it.

The indirect injectors should still be spraying atomised fuel in a predetermined pattern, so not just a valve that opens and lets "some fuel" through. I've owned indirect injection cars, typically cars with Bosch K Jetronic mechanical injection where the "injectors" were just spray heads that were forced open by high-ish pressure fuel being pushed down their supply pipes, even they could give this sort of problem, and with one car one injector did, Ford dealership didn't recognise it was being a problem, but after they had bodged up another issue, I ended up demanding that this "not correct" leaking of fuel into a single cylinder was not acceptable, so I bought a single new "injector" and solved that problem quickly - then went on to getting the originally faulty injector working, these K-Jetronic injectors were just spring loaded valves that were designed to vibrate while open and by doing that they should have always been able to "self centre" and so close and seal off fuel when the supply pipe pressure dropped - this one had ended up getting stuck/located so that it could not close properly. A friend that had a Ford Escort RS Turbo bought that injector from me and it seemed to help him solve a similar issue!

Edit:- I fully understand why you are digging deeply into this, but maybe try stepping back from it and enjoy your car - though easier said than done!