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

[ULIK]

nothing, not a puff. Not even if its been sat for a full week. Even if i get someone else to start it. There is no smoke all. I cant say what the issue is exactly just that i 100 percent dont have it. My cupra is the 2020 model with the dq381 and NO MPI... so i should have more carbon buildup than the earlier models. Yet no smoke ever. Its the valve cover for sure. They just dont want to do the job so they blame it on carbon.

Valve cover? Can be, because I found some oil on spark plugs threads on 1 and 4th cylinder. but the spark plugs head was clean. How can oil get to the cylinder from threads, it should be sealed when tightened?Right or wrong?

 

[The-Cupra]

My car is 134k (kilometers) now (but first puff was observed at 78k when it was stock and with original exhaust system). End of 2017 with 8 injectors. Bigger turbo inlet, K&N filter and bigger pipe from filter to inlet+ catback and downpipe custom+ performance spark plugs. Was remaped with ECU and TCU now it's stock. Run on remap something about 20 then I've done backup, because one mechanic wanted to get to stock again to check parameters on VCDS-claiming that the car is overfuelled. After that he wanted to pull the engine tear him apart and search for issue- claiming finaly that it's valve steam seals (expected costs 4-5k euro). Thats not the way I wanted the probem to be solved. So the car is stock and still smoking on startup. When I was switching the PCV the old one looked ok. Last thing to replace before deassembling the motor is again the PCV (with tuned PCV and catch can) and carbon.

Do you have any oil on top of the spark plugs or on the spark plug threads? Pop your hood, pull the plastic engine cover, pull the clips on the coil packs, then pull each coil pack and check your plug wells. If there’s oil in there at all that’s your problem. It’s not uncommon for oil to seep past the valve cover seal and drip past your plugs into your cylinders. If it sits and builds up it’ll burn off right when you start and you’ll get smoke.

If there is non then it could be your PCV and i would replace it. Then if that doesnt solve it maybe it could be the valve stem seals however valve stem seals would be a big puff of blue smoke.

 

[The-Cupra]

Valve cover? Can be, because I found some oil on spark plugs threads on 1 and 4th cylinder. but the spark plugs head was clean. How can oil get to the cylinder from threads, it should be sealed when tightened?Right or wrong?

Its coming from the valve cover, there is a sealant (not a gasket) that covers between this and the top of the engine... its leaking and its common. This is your issue NOT valve stem seals. I believe its like a 1k job.

 

[ULIK]

Thanks guys. So It's going to be replaced/fixed in first place. Maybe untill the end of the week. Will keep you informed.
Regards.

 

[AVCUPRA290]

nothing, not a puff. Not even if its been sat for a full week. Even if i get someone else to start it. There is no smoke all. I cant say what the issue is exactly just that i 100 percent dont have it. My cupra is the 2020 model with the dq381 and NO MPI... so i should have more carbon buildup than the earlier models. Yet no smoke ever. Its the valve cover for sure. They just dont want to do the job so they blame it on carbon.

at least it is not linked to the turbo inlet pipe disturbing the vacuum of the PCV (it can cause oil surge on track) since you also have an aftermarket one.
(I’ll probably go back to pikey mod after selling my full r600 kit do you mind telling me which panel filter you’re using ?)

only differences are the stock exhaust and no bi injection on yours. I’ve tried without res delete and it smoked too and ULIK’s did smoke stock from what I’ve read.
Could be the MPI letting some fuel dripping inside the manifold on top of the intake valves or within the cylinders which makes the car over fueled for a warm startup hence smokes.. and nothing after a full night since the gas evaporated. Could explain those pictures I took : you can see within the manifold on top on the intake valves where the MPI injectors are, it looks oil clean but still wet in some places. The cylinder pictures are from one of my cylinder after I stopped the engine, it is dirty cause I had some injector cleaner left in the fuel I think but the borders look transparent which led me to think it is petrol (that’s why I’ve replaced the injectors)

Only real difference between our cars is the bi injection I guess.. I have the revised PCV so we probably have a similar version…

 

[AVCUPRA290]

Its coming from the valve cover, there is a sealant (not a gasket) that covers between this and the top of the engine... its leaking and its common. This is your issue NOT valve stem seals. I believe its like a 1k job.

One mechanic told me that but it cannot come from the valve cover. If you look at the picture, if oil was passing through the sealant it will fill the plug well and not go inside cylinder. So it will in the worst case cause misfires.
But there is no way the oil is dripping along the plugs if they are screwed..
or there is another way for the oil to go inside the cylinders but please let me know I’ve considered this option with no viable answer.
+ I didn’t see oil within my cylinders and still got smoke on startups.

below some pictures linked to this valve cover idea. I’ve found some green residue of the sealant when I’ve looked into the wells with a cam, I think the one in the cylinders fell in because of the cam. The other green bits were in the well where the plug is. As you can see there is no oil on the plug thread..
The sealant is probably under some pressure and heat or my old PCV messed up so pressure was higher and some sealant moved.. don’t know why I got some. Maybe I took the plugs out too many times also.

 

[AVCUPRA290]

Thanks guys. So It's going to be replaced/fixed in first place. Maybe untill the end of the week. Will keep you informed.
Regards.

If it works please let me know !
Sorry for the delayed answers didn’t catch all your posts in between

 

[ULIK]

I will try to fix the cover. With 134k on dashboard it's time to check the timing chain so the mechanics will do a revision that needs to be done on this milage (the timing chain cover must be removed to desamble the valve cover). Untill the end of week I should have some answers about the valve cover. If it works maybe I will give this car a second chance

 

[The-Cupra]

at least it is not linked to the turbo inlet pipe disturbing the vacuum of the PCV (it can cause oil surge on track) since you also have an aftermarket one.
(I’ll probably go back to pikey mod after selling my full r600 kit do you mind telling me which panel filter you’re using ?)

only differences are the stock exhaust and no bi injection on yours. I’ve tried without res delete and it smoked too and ULIK’s did smoke stock from what I’ve read.
Could be the MPI letting some fuel dripping inside the manifold on top of the intake valves or within the cylinders which makes the car over fueled for a warm startup hence smokes.. and nothing after a full night since the gas evaporated. Could explain those pictures I took : you can see within the manifold on top on the intake valves where the MPI injectors are, it looks oil clean but still wet in some places. The cylinder pictures are from one of my cylinder after I stopped the engine, it is dirty cause I had some injector cleaner left in the fuel I think but the borders look transparent which led me to think it is petrol (that’s why I’ve replaced the injectors)

Only real difference between our cars is the bi injection I guess.. I have the revised PCV so we probably have a similar version…

Im using the ITG panel filter which is also the same as the racingline filter. They are made by the same manufacturer but ITG sell it cheaper. I also have the blanking plate and the other side fully dremeled out.

Pardon our interruption...

I dont have MPI so i cant comment, however if you have tried everything else then it could be due to the MPI letting fuel drop over the top of the valves and down into the cylinders. I believe there are many revisions of the PCV. Mine is a 20 plate so i think i will have the latest revision. However, like i said i can leave mine for a week straight and there wont be a puff of smoke on startup so something is going on.

 

[The-Cupra]

I will try to fix the cover. With 134k on dashboard it's time to check the timing chain so the mechanics will do a revision that needs to be done on this milage (the timing chain cover must be removed to desamble the valve cover). Untill the end of week I should have some answers about the valve cover. If it works maybe I will give this car a second chance

Yes, that would be the best time to do it. Get it done with the timing chain.

 

[AVCUPRA290]

Im using the ITG panel filter which is also the same as the racingline filter. They are made by the same manufacturer but ITG sell it cheaper. I also have the blanking plate and the other side fully dremeled out.

Pardon our interruption...

I dont have MPI so i cant comment, however if you have tried everything else then it could be due to the MPI letting fuel drop over the top of the valves and down into the cylinders. I believe there are many revisions of the PCV. Mine is a 20 plate so i think i will have the latest revision. However, like i said i can leave mine for a week straight and there wont be a puff of smoke on startup so something is going on.

Off topic so I’ve sent you a private message related to your dry filter.

For the puff of smoke that’s the weird thing about it : I don’t have any smoke if the car sit more than 7-8hours. Meaning even after 2 weeks I won’t have any smoke.
It is only startups after 20min to 7h let’s say.
That’s why I though it was petrol related cause it could evaporate within this laps of time, or it is oil that can drip back from where it came (like PCV hose or something but unlikely to be the valve steam seals). Same for valve cover how the oil could not create smoke after a week ? (If admitting it can go through the plug threads which I think is unlikely as I mentioned in my previous post but will see how it goes for ULIK)

 

[ULIK]

Off topic so I’ve sent you a private message related to your dry filter.

For the puff of smoke that’s the weird thing about it : I don’t have any smoke if the car sit more than 7-8hours. Meaning even after 2 weeks I won’t have any smoke.
It is only startups after 20min to 7h let’s say.
That’s why I though it was petrol related cause it could evaporate within this laps of time, or it is oil that can drip back from where it came (like PCV hose or something but unlikely to be the valve steam seals). Same for valve cover how the oil could not create smoke after a week ? (If admitting it can go through the plug threads which I think is unlikely as I mentioned in my previous post but will see how it goes for ULIK)

I think valve cover can do that. Even if car sits for a long time I don't have the puff but still exhaust gases smell like I'm running on liquide petroleum gas (LPG) -when I start it up in the garage the smell can be compared to that. My wife even told me that we have a gas leak in garage . I think that when car sits the oil that leaks on the pistons is getting more dense. When it starts when cold the reps are higher, more fuel added on start and maybe the smoke is not observed but it (gasses) still stinks as hell (or as LPG)- I think that's oil burning but thanks to the higher fuel dose and higher reps it is burned more effectively- not observed as a puff. Car is scheduled for a repair on Tuesday next week. I will pick it up on Thursday. Then I can tell something more about the condition of the cover and the sealant itself. Fingers crossed for successfull repair

 

[ULIK]

Hi. So the car is back. They checked the timing chain (no need of replacement, all parts in good condition). After they pulled out the plugs, guess what- no oil on threads, no sign of oil in the plugs hole (1 week before I've changed the plugs and on the old ones there was oil on threads- a lot of it, done something abouth 1k kilometeres from that time). So they didn't done anything except checking the chain . According to them it's not the issue- not worth money to dismantle it. So what next- observe, wait untill the timing chain will be needing replacement then they will take the cover out because for changing the cover they need to remove the timing chain- thats what they said to me. Still no answers. I'm giving up Sory I can't deliver any new ideas how to deal with this problem. Maybe i need a better mechanic and definitly I need a new car
Good luck guys maybe some one will find the issue. Of course if something changes I will report it here.
Regards.

 

[ULIK]

Hi guys. Found something on youtube that might be the answer:

According to them when you change turbo inlet there will be a higher suction developed before turbo that can damage PCV(and maybe the suction is big enough to suck oil from it). It can be it because my car smokes on start when i revs up during start (all those engines do that after short stop). When it starts on start/stop system it doesn't revs so the suction is lover and no smoke observed.The oryginal PCV is developed to work only with stock inlet, if you change the inlet problems with PCV can start to show because of the bigger air flow and suction. So I'm throving out the aftermarket turbo inlet and going back to stock to see if it changes anything. It looks like now the best upgrade for cars that are tracked is a PCV system from MK8 a full retrofit that is even better then oil catch tanks with tuned PCV (or even PCV plate from ARP).

 

[AVCUPRA290]

Hi guys. Found something on youtube that might be the answer:

According to them when you change turbo inlet there will be a higher suction developed before turbo that can damage PCV(and maybe the suction is big enough to suck oil from it). It can be it because my car smokes on start when i revs up during start (all those engines do that after short stop). When it starts on start/stop system it doesn't revs so the suction is lover and no smoke observed.The oryginal PCV is developed to work only with stock inlet, if you change the inlet problems with PCV can start to show because of the bigger air flow and suction. So I'm throving out the aftermarket turbo inlet and going back to stock to see if it changes anything. It looks like now the best upgrade for cars that are tracked is a PCV system from MK8 a full retrofit that is even better then oil catch tanks with tuned PCV (or even PCV plate from ARP).

Did it solve your problem ? Because I did put back the stock inlet too (I’ve followed those mk8 PCV tests) but smoke is still there.
Maybe I would need to replace again the PCV but I think it is working well so it’s probably a waste

 

[ULIK]

Hi. I wasn't able to replace it yet- lack of time and..... COVID 19 so I was puffing like my Cupra whole last week But it's a bad news what you observed I will replace the whole intake for stock (even the filter). I'm not looking for a total solution (because of almost completely removed exhaust system) but maybe a slight improvement. If it doesn't help maybe I will invest in PCV retrofit from MK8. It will be way cheaper and worth to try. After that it will be probably one solution- Valve steam seals. But for that repair I need to wait untill timing chain replacement, and it will be a while yet, due to it's perfect condition.

 

[AVCUPRA290]

Hi. I wasn't able to replace it yet- lack of time and..... COVID 19 so I was puffing like my Cupra whole last week But it's a bad news what you observed I will replace the whole intake for stock (even the filter). I'm not looking for a total solution (because of almost completely removed exhaust system) but maybe a slight improvement. If it doesn't help maybe I will invest in PCV retrofit from MK8. It will be way cheaper and worth to try. After that it will be probably one solution- Valve steam seals. But for that repair I need to wait untill timing chain replacement, and it will be a while yet, due to it's perfect condition.

The MK8 PCV retrofit is usually for oil surges happening on track with high boost cars (mostly) and aftermarket turbo inlet.
I think some cars can also have oil surge with stock inlet and some with aftermarket inlet don’t have any issue.
I don’t think the startup smoke issue is related. Might just reduced a bit the oil being sucked up by PCV because of vacuum alteration by aftermarket inlet. But as I said I still have the smoke with everything back to stock.

 

[ULIK]

Ok so I got back to OEM parts. After I cleaned the turbo from oil on intake side (some oil got there from PCV) first few starts of the car were different on warm engine after about 1h of sitting. No smoke, the revs were stabile (when he puffs they are unstabile for 1-2 sek). After 3-4 starts the smoke came back and revs are again unstabile but I think that there is less smoke coming from exhaust. So it's interesting. I will observe it, but maybe it is the problem with PCV and maybe it got damaged by the aftermarket inlet. On GOLF forum one guy adviced to run the car for a week on stock inlet and the difference should be observed. So what's left is to drive the car for a while and check for changes. According to my mechanic there were cases when they bought new PCV and it was damaged when it came to them. In one case 3rd ordered PCV was ok (all them OEM parts). After a week I will share my experience with stock parts.
Regards.
G.

 

[AVCUPRA290]

Ok so I got back to OEM parts. After I cleaned the turbo from oil on intake side (some oil got there from PCV) first few starts of the car were different on warm engine after about 1h of sitting. No smoke, the revs were stabile (when he puffs they are unstabile for 1-2 sek). After 3-4 starts the smoke came back and revs are again unstabile but I think that there is less smoke coming from exhaust. So it's interesting. I will observe it, but maybe it is the problem with PCV and maybe it got damaged by the aftermarket inlet. On GOLF forum one guy adviced to run the car for a week on stock inlet and the difference should be observed. So what's left is to drive the car for a while and check for changes. According to my mechanic there were cases when they bought new PCV and it was damaged when it came to them. In one case 3rd ordered PCV was ok (all them OEM parts). After a week I will share my experience with stock parts.
Regards.
G.

How did it go?

 

[ULIK]

Smoke still is present but I think that smaller amount of it is now getting out of the exhaust. Maybe it's just my imagination It can be the weather- it's cooler outside. I will try to do some tests with the inlet elbow- whipe out the oil residue from the inlet that comes from the PCV house and try to start the car few times. When I changed the inlet and pipe for stock first 3 start were smoke free and with stabile RPM. If the cleaning helps then maybe PCV will be replaced or oil catch tank mounted. I just need to finde some free time to do it. That the last thing to do after that- cylinder head repair. I think that it can be valve steam seals itself but also valvs and valve guides- that's why many users after the valve steam seals replacement notice the same problem after just few tkm later.