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My Twin Turbo Mustang GT 2018 Oil in spark plugs hoes and on top of the spark plug

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Hello,

I've been to a service and they find out that the Cylinder 3 it's slightly low in the compression test, they found oil in the Spark plug on Cyl 3, cleaned them and swap the spark plug 3 with 1 and the misfire is gone. But you can still smell burn oil, do you think it's just the o-ring or head gasket or something bad?

Many thanks!
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Get a camera into the cylinder and see if there's any obvious damage to the piston or cylinder wall.
Blown head gaskets don't generally introduce oil into the cylinder.
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I agree to get a camera to inspect the cylinder.
It's not as common for an engine to burn oil from a head gasket as it is coolant but it's sometimes possible for oil to get into the combustion chamber from a blown gasket. The possibilities here are a damaged cylinder and/or piston, piston rings, blown head gasket, or a badly leaking valve stem/damaged valve.
I've seen some videos online where they fixed the oil in the spark plugs hoes and on top of the spark plug with changing the o-ring under the spark plug (inner gasket)
WHY THERE IS OIL IN SPARK PLUG WELL, ENGINE MISFIRE FIX - YouTube
or
(250) Oil on Spark Plugs? Diagnose and Fix Spark Plug Tube Seals! - YouTube
I mean when I cleaned the spark plug and swap 3 with 1 the misfire was gone, why if the cyl it's damaged?
Just had the same problem on a different car. But I would think you would have the same issue. The valve cover spark plug tube seal was bad. Replaced tube seal and valve cover gasket now no oil leaking on to top of spark plug.
Yeah, that's what I hope it is, Finger crossed it's not something bad
Just something like this: valve cover spark plug tube seal - Google Search
valve cover gasket
The bigger concern here is getting lower compression in the affected cylinder. If it was only a very slight difference then it's not a big deal.
What was the compression they measured compared to the others?
I've been to a service and they find out that the Cylinder 3 it's a bit low in the compression test, they found oil in the Spark plug on Cyl 3, cleaned them and change spark plug 3 with 1 and the misfire is gone. But you can still smell burn oil, do you think it's just the o-ring or head gasket or something bad?
I've seen some videos online where they fixed the oil in the spark plugs hoes and on top of the spark plug with changing the o-ring under the spark plug (inner gasket)
WHY THERE IS OIL IN SPARK PLUG WELL, ENGINE MISFIRE FIX - YouTube
or
(250) Oil on Spark Plugs? Diagnose and Fix Spark Plug Tube Seals! - YouTube
I mean when I cleaned the spark plug and swap 3 with 1 the misfire was gone, why if the cyl it's damaged?
Do you mean the valve cover o-ring that encircles the plug or the crush washer at the top of the plug threads?
What part of the plug did you clean?
Were you actually getting oil in the cylinder(burnt oil on the electrode) or was the oil just in/on the coil boot and upper part of the plug?
You said that you cleaned the plug so if the plug was misfiring from oil contamination that should clear up the problem.
A cylinder with lower compression doesn't automatically mean that it's a dead cylinder. It depends on how low it is.
Oil from a valve cover leak won't really get into the cylinder to foul the plug since the plug is sealed to the head when it's tightened. Maybe some oil could leech down the threads if the plug wasn't tight or there was a defect but it shouldn't usually happen. When you unscrew the plug from the head and there's oil on the threads it's then deposited onto the threads as it's unscrewed. This gives the appearance of oil leaking down the plug even though it's not.
I mean these O-rings
Imgur: The magic of the Internet



I don't remember the exactly numbers that they told me for the compression test but he told me that Cyl 3 it's slightly low
But I have these reading from their diagnosis
From what I can see the Compression test (I think) was ok when he cleaned and swapped the spark plug (3 with 1)
Imgur: The magic of the Internet

I will take out the spark plug and check out if there is any oil in the hose on on top of the spark plug
The bigger concern here is getting lower compression in the affected cylinder. If it was only a very slight difference then it's not a big deal.
What was the compression they measured compared to the others?

Do you mean the valve cover o-ring that encircles the plug or the crush washer at the top of the plug threads?
What part of the plug did you clean?
Were you actually getting oil in the cylinder(burnt oil on the electrode) or was the oil just in/on the coil boot and upper part of the plug?
You said that you cleaned the plug so if the plug was misfiring from oil contamination that should clear up the problem.
A cylinder with lower compression doesn't automatically mean that it's a dead cylinder. It depends on how low it is.
Oil from a valve cover leak won't really get into the cylinder to foul the plug since the plug is sealed to the head when it's tightened. Maybe some oil could leech down the threads if the plug wasn't tight or there was a defect but it shouldn't usually happen. When you unscrew the plug from the head and there's oil on the threads it's then deposited onto the threads as it's unscrewed. This gives the appearance of oil leaking down the plug even though it's not.
Those are the spark plug well gaskets/seals.
They would have written down the results of the compression test.
You may be confusing a compression test with the power balance test that they performed to track down the cylinder that wasn't performing correctly.
So, from what I understand here you had a misfire solely because of oil being in the spark plug well of #3 which caused a misfire to the valve cover. If they replace the valve cover gaskets/seals then you should be fine. If there was oil in there before it's likely it will fill up again until they replace the gaskets. My guess is that you likely have no compression or cylinder issues.
The reason that cylinder would be low is do to raw fuel washing the cylinder wall down since there was no spark. No spark was from all the oil on the top side of the spark plug causing the coil to ground. Once gasket, coil, spark plug replaced after a few hours the compression should be back to within specification.
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Yes, my fault I just realised that. But he also told me that Compression test was one 108 or so and slightly lower on Cyl 3

I drove the car like 5 miles back home and today I have opened the coil pack on the Cyl3 and everything in there was clean even if he didn't changed any seal/gasket/valve cover so there are 2 options.
1. 5 miles was too less to see oil again there
or
2. The problem is that the oil it's on top of the spark plug (I couldn't take it out too see if there is oil on top) which is bad
Imgur: The magic of the Internet

But now the misfire is gone, just some burn oil smell and a bit of smoke but not as it was before. Maybe just some residue left somewhere.

I've made an appointment to a Race garage who done Twin Turbo in the past and I hope they don't screw me up
You may be confusing a compression test with the power balance test that they performed to track down the cylinder that wasn't performing correctly.
It's probably not anywhere near enough engine run time to make the oil accumulate in the plug well again. That process likely took a very long time to make itself evident. The oil didn't come from nowhere so either the valve cover gaskets get replaced or the oil eventually comes back to create more misfires again. Those are the two outcomes here.
I can see in the pic link that there's no oil in the plug well, yet that is.
Why would you pay a performance shop/garage to do something on your car? A valve cover gasket leak is a very standard thing to deal with. Any decent shop or even better a dealer will be more than qualified to do the repair.
Also, isn't this still under warranty? Here in the USA we have a 5 year powertrain warranty.
5 miles was too less to see oil again there
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That garage it's the only one here in the UK where that modified a Mustang Twin Turbo, and I need more tips about my car like what oil I should use, what gap I should use on my spark plugs, I would like they can check the Twin Turbo kit as one turbo has some oil on it ( Imgur: The magic of the Internet )
I have received the 93 base tune from the guy modified the car back in Houston but the tunner from race shop told me that he can make it safer to drive daily (as I want to drive this car trough Europe)
I also found some plugs near the horn unplugged and maybe they can advise what that is (I know that someone stole the 2Step from the car maybe that is)

I think I don't have any warranty coming with this car as it's imported from the USA to the UK
It's probably not anywhere near enough engine run time to make the oil accumulate in the plug well again. That process likely took a very long time to make itself evident. The oil didn't come from nowhere so either the valve cover gaskets get replaced or the oil eventually comes back to create more misfires again. Those are the two outcomes here.
I can see in the pic link that there's no oil in the plug well, yet that is.
Why would you pay a performance shop/garage to do something on your car? A valve cover gasket leak is a very standard thing to deal with. Any decent shop or even better a dealer will be more than qualified to do the repair.
Also, isn't this still under warranty? Here in the USA we have a 5 year powertrain warranty.
I forgot that this is a turbocharged engine. There would be no warranty at this point regardless.
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Hello,

I have dried the fuel tank because I still had some Ethanol in it from the plug goes into the fuel rail. Swapped the tune, filled with petrol but now I can't see any fuel goes in to the fuel rail. What do you think cause this? the new tune?

Thanks!
I forgot that this is a turbocharged engine. There would be no warranty at this point regardless.
What does this mean?
If the fuel pump is coming on then you have to crank the engine until the air bleeds out of the line. It takes a while. A bad tune would have to be really bad for it to not turn on the fuel pump.
I still had some Ethanol in it from the plug goes into the fuel rail.
I tried to disconnect the fuel line, put the ignition on but no fuel coming anymore. So I think the fuel pump it's not pushing anymore
I tried to turn on the engine many times, the problem is that the engine it's starting but it's dying immediately.

I have removed the rear seats, I can hear the click from the fuel pump but nothing coming out from it. That's strange. It could be the tune itself? I should try to put the E85 tune back in to see if the fuel pump it's working again?
What does this mean?
If the fuel pump is coming on then you have to crank the engine until the air bleeds out of the line. It takes a while. A bad tune would have to be really bad for it to not turn on the fuel pump.
When you turn the ignition to on you should be able to hear a low hum sound from the pump if it's coming on. If not, then you will only hear a relay click sound from the FPDM(fuel pressure driver module).
Scan the car for codes. If this happened immediately after putting in a new tune then I would suspect the tune. Simply reload the older ethanol tune to see if that corrects the issue and makes the pump pressurize the system. If it does, then you know the new tune is to blame and I would never use that tune ever again.
I tried to disconnect the fuel line, put the ignition on but no fuel coming anymore. So I think the fuel pump it's not pushing anymore
I tried to turn on the engine many times, the problem is that the engine it's starting but it's dying immediately.

I have removed the rear seats, I can hear the click from the fuel pump but nothing coming out from it. That's strange. It could be the tune itself? I should try to put the E85 tune back in to see if the fuel pump it's working again?
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Yeah, I swapped the tune. on E85 the car started right up without any issue. definitely it's the tune, so I paid $250 to LPF for nothing :(
I need other 93 tune.

Hello, I have some updates.
They solved some of the issues, there was no oil in the spark plugs anymore but there was different gaps between them, the oil filter was loosen. They installed 2 ford performance oil catch can and now I'm waiting for them to develop a tune for my car with cats on, on 93 base as it is, twin turbo.

I'll keep you updated!
When you turn the ignition to on you should be able to hear a low hum sound from the pump if it's coming on. If not, then you will only hear a relay click sound from the FPDM(fuel pressure driver module).
Scan the car for codes. If this happened immediately after putting in a new tune then I would suspect the tune. Simply reload the older ethanol tune to see if that corrects the issue and makes the pump pressurize the system. If it does, then you know the new tune is to blame and I would never use that tune ever again.
There's definitely a very slow leak with your valve cover gasket around the spark plug so that oil will eventually come back. It might just take months or a year to notice it.
The two PCV oil catch cans were a good idea but you have to empty them every now and then. Only one will really collect much oil though. I would check them every time that you do an oil change.
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