My 2015 3.0 TFSI had a misfire running the highway on the way home one fatefull night, shutting that cylinder off creating havoc and shaking.
I have a couple of prior threads posted, while working through this issue after the mechanic stated get a new motor. And I commented on a thread with several fighting the dreaded heavy oil consumption thingy, as I had that just prior and leading to this current issue!
I have had many chime in with other ideas, and I appreciate that, thats why we are all here. Currently, got a great guy helping me troubleshoot deeper.

The shop stated that when pulling the spark plug in #5, found the tip missing and #5 cylinder only had 30lbs compression, while #4 had 90lbs, the only 2 they mentioned. There is a slight scoring in the cylinder.
They stated that they Walnut blasted the valves and the compression came up a little in 5.
They replaced the plugs and coils. No change.
After NOT getting it sorted, they suggested a donor motor due to broken rings.
Taking the gain in compression as a good sign, after bringing it home, I did a piston soak with B12 Chemtool, while keeping fingers crossed that it was stuck rings, setting for a couple of days. Blew that out, installed plugs and coils. Still misfiring. AND I cannot clear several modules codes stored. When I do clear them, they just reappear before I can go back out.

I did an EPR oil flush, adding 2 cans and running for 25 minutes at 2000 rpm, twice in a row, a couple days apart.
I changed oil to Valvoline Restore and Protect.
I drove it approximately 4 miles round trip, hoping something magnificent would happen.

It was recommended to check compression myself, so I did and after I checked compression, found all cylinders excepting #5 have 150 ish lbs, near perfect right? I mean, #4 came from 90 to normal, right?
#5 has zero! How would it go from 30 to gaining to zero?
I ran the test twice after, with oil in the cylinder to make sure I had seal, but nothing. After all, B12 stayed in the cylinder.
I could hear the difference between #5 and all others, it just spun freely.
I had my wife crank it while watching and videoing the gauge, not even a flinch! Slight, spi sound when I pressed the release button.
Next we will remove the valve cover and check the valve train for abnormalities!
Any other ideas or thoughts?

Thank you in advance!

 

Zero?! I would think it means a valve isn't closing properly, like a broken spring or something physically stuck in there. You did mention that the old plug was broken, so maybe it is something caught? Still, that was a while ago, and you still had a little compression at that time. The fact that you were able to get the soak to hold is a good sign for the piston rings.

 

Well, thank you!
That is exactly where we are, me and the remote mechanic helping me trouble shoot, in our thinking.
The shop that worked on it doesn't answer my email with questions, after they had done the work and sent me off with a dilemma. They still believe it needs an engine.

So far, yes, I put oil in the cylinder to ensure there proper sealing of the rings during test. A few days later, the oil is still there.
Today I removed the valve cover, checked the springs and all seem to have the same tension as the good cylinders on either side, using my fingers. All looks very normal and good and clean.
The cam lobes seem identical in wear and of course, I cannot see the actual valves. If I had a leak tester, might be a different story.
I did turn the engine by hand and inspected both up and down. Nothing seems out of order.
I do have this endoscope with arriving tomorrow: So I should have a much better idea after viewing the valves.

The shop did mention that they did a leak test and air escaped the dip stick tube. Could this happen with a valve?

Thanks again!

 

Dipstick tube is only connected through the oil pan at the bottom of the crankcase, so that is indicative of ring escapement... or PCV issue, I think, could also cause pressure buildup there.

 

Well, I am not ruling out the PCV, shortly after I had it changed, is when the oil consumption started.

 

Hey guys!
I bought an amazing endoscope and received it this afternoon.
I really like this one! I can post link if anyone wants it.
Seems like we found the issue, so I will be calling some shops to get it repaired first thing tomorrow.
See the rings appear to be holding the oil for a few days now.
See the giant chunk of valve missing?
The shop claimed #5 had 60lbs on the receipt, so this happened after I left with it, and cylinder 5 was still not working? And now its zero?
Their receipt also said #4 was 93lbs, but all cylinders are now at 150 +/-
Now, I do still think I have an issue with the PCV valve, where would you source the proper part from? Would you know the part # needed? Seals or grommets?

Thanks everyone!

Imma try to get some better photos of all cylinders in the morning.

 

Holy smokes! Yeah, that would definitely do it. Wow.

Edit: Seems like it's been a while since those images were taken, though. Are you sure that's the problem?

Definitely share that unit, because it's rare you see an endoscope image with that degree of clarity.

 

I scoped it yesterday and these were the images I snapped.
I will get better ones today and all cylinders, since I am in that far.
Here is the link for the scope: I am not tearing into this, I will find a pro to do the repair, but man I can hardly wait to get it back already!
I feel the shop that was working on it was very lacsidasical in their diagnosis, I mean, I am not a mechanic, but highly mechanically inclined and I, with the help of and a shout out to Mike the Mechanic (kinda Kool ring, huh?) with his guidance and knowledge base and the "don't lose hope" attitude, discovered this. If he were closer, he would be repairing it!
So I have a bunch of calls this morning and hopefully can get this in very soon.

 

This makes me a bit less worried about my vehicle, as my mechanic scoped the cylinder for me and specifically checked the valves for damage. Hoping once I do all my spark plugs that it fixes my misfire issue. I'm going to have him replace my HPFP too to hopefully help with my long cold starts. Thank god for tax season haha! This car is starting to nickel and dime me, but I suppose that comes with the mileage too. Glad you finally tracked your issue down, sorry that it's not something easier/cheaper to replace.

 

Once mine is up and running, I am going through to address many things, like the fuel filter, parasitic door handles, etc. So I get you!