Pathfinder7

I picked up a sweet 2020 SQ8 a couple of months back and all has been well. Two things happened around the same time, I took it in for a 30k service and I put in a BMC oiled air filter (a terrible idea in retrospect).

There’s no Audi dealer within three hours so I called the local VW shop. They said they could handle the oil change and spark plugs for a reasonable price. It took them much longer than they expected since they initially had the quote from a V6, but they got it done.

I picked it up and drove it home with no issues. The next morning, I noticed the CEL and took it back in. I was worried they did something wrong and so were they. They reported misfiring in cylinder #2 and suspected a bad plug. They ordered a new batch to be sure, but replacement did nothing. They then noticed some red oil residue on the #2 cylinder coil and suspected the BMC. They ordered another coil and replaced, but the misfires continued and even moved around, all on the same bank of cylinders 1-4, mostly on 1 and 2.

They removed everything and cleaned out more residue claiming there was a soda can full. I’m sure that was an exaggeration, but still some was removed. They then thought it was a “sensor” fouled with oil. I asked about a MAF, but they said it does not have one. I’m unsure if they were talking about the O2 sensors on the cats. Regardless, they swapped them from left to right thinking the misfire would move to the other bank, but it didn’t.

They removed the oiled filter and out in a OEM one. They have been running the car at idle for a couple days hoping to burn off excess oil, but claim the misfire is actually worse. It’s mostly cylinder 1 now. They have no more ideas and admitted the engine and problem is beyond their knowledge, they have had the car for two weeks now. They have called Audi looking for any known issues that might cause this, but think it may need to be towed three hours away for “expert” eyes.

My question is could excess filter oil cause this and why? I know they can clog an MAF, but apparently there isn’t one. It’s oil, so if it gets anywhere else shouldn’t it just burn off eventually? Could it have fouled the O2 and they need cleaned or replaced? I didn’t get a straight answer if they cleaned those sensors before the swap. If not the oil, what else could be the root cause?

Any thoughts or ideas would be appreciated

BOASTY

You need to know the specific fault codes in order to being to diagnose what is going on. The misfire and CEL are only symptoms and we can only guess what could be the root cause without a full scan. Do you know the full list of codes and the specfics one(s) causing MIL?

What do you mean by this? Can you clarify what you meant here? What was removed and what residue and where? Is this the same "red oil residue" you mentioned on the #2 coil?

I highly doubt any filter caused this. This engines are difficult to do plug changes on and even some of the best Audi/VAG shops won't do it. My guess is that the shop damaged something.

Pathfinder7

Boasty,

Thanks for the reply. I don't know the specific codes, but I'll definitely ask. They stated generically that the codes were "misfire in cylinder 1".

As to the cleaning, the residue cleaned was the red oil. I assume they mean they cleaned it from the engine intake from the filter to the catalytic converters before the turbos. I haven't familiarized myself with the pathway of air, but that makes the most sense. I am unsure how the oil could have made its way into the coil which I assume is just sitting above the spark plug itself on each cylinder.

I knew the plug change took time and required the removal of a lot of parts, but I didn't realize it was so challenging. What could go wrong with the changing assuming they put everything together properly?

It sucks about the excess filter oil because they are leaning hard into that being the issue. They are being helpful and doing most of this on their own dime, but I fear they firmly believe the oil is the culprit without any data to back that up. I was inclined to just go get it and clean it myself, but now I fear they have done even greater damage.

The factory warranty expires in a few days and this delay and lack of experience has drawn the issue out without a solution. I let them do it because I didn't have the time to drive the car up north, letting it stay there for a day, then drive back afterwards. Now, it's been with these guys for two weeks and is even worse off than before. It will likely still need to go up north, though it will have to be towed. It's gonna drag on and probably be a fight to get them to fix the problem.

Pete_SQ8

Could they or the oil have damaged the coil pack on the misfire cylinder? If they did another set of plugs what else is there but the coil pack

Pathfinder7

We thought that might have been the case, but they replaced the coil and the problem still exists. Plus, it moves around to different cylinders on the same bank so it isn't cylinder/plug/coil isolated.

Pathfinder7

Ok, more info.

-The codes were P0301 and 0302, just misfires in Cylinder 1 and 2.

-The sensors they removed, cleaned and swapped from left to right were the MAPs. No change with the swap.

-They changed all 8 spark plugs a second time with a new batch after the first detection of the misfire. No change.

-The coil from #2 was replaced. No change.

-They cleaned the filter oil from the filter outlet through the intake hose up to before the turbos.

-The car idles smooth and quiet, but he says the misfire and stutter can be felt when driving at about 50% throttle.

-The Audi dealer up north (Bend, OR) hasn't returned either their or my phone calls. This dealership's master mechanic is out this week and they don't have anything but superficial level Audi software, whatever that means. They say there exists nothing like this engine configuration in the VW line so they are out of ideas.

I've asked around for a local euro mechanic and gotten the same name from a couple people. I'll take it to them next.

retom

First question, did you oil the BMC filter yourself or install a brand new one? Have you seen this excess oil on the coils yourself?
I don't think the BMC filter is the cause of the problem. The SQ8 TFSI does not have MAF or any catalytic converters before the turbochargers, and the air path from the filter to the engine is long. Potential excess oil from the filter would settle on turbocharger blades, air ducts, air pressure sensors or intercoolers. I have never heard of a BMC filter in a petrol engine causing failures like in your car and also contaminating the coils.
I think the reason may be different. Maybe the workshop did something wrong because replacing spark plugs and coils in this engine is quite complicated. This all sounds a bit strange. It would be good to know the fault codes because without them it is just blind speculation. Please let us know how you solve the problem. Good luck!
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BOASTY

They are leaning in on the filter because they don’t want to take responsibility and/or can’t figure it out. They could have damaged any number of things including mechanical or electrical, components, wires, sensors, etc. I can almost guarantee it’s not the filter. The oil on these filters is sprayed on in very limited quantities and no where near enough to fill a soda can. This red oil that you mention is likely the culprit but it’s not coming from the BMC filter. You need to find the source. Where did they find a soda cans worth? Can you get the full engine scan?

If this oil is collecting in the air box around the filter I’ll bet they didn’t reconnect the PCV correctly. Beyond the filter does this have a stock intake otherwise?

retom

Yes, I also don't believe in a story about BMC filter. The list of potential sources of misfire is long:
- Faulty or worn spark plugs.
- Worn or damaged ignition cables.
- Coil damage.
- Faulty oxygen sensor.
- Damaged fuel injectors.
- Vacuum leakage.
- Low fuel pressure.
- Damaged camshaft position sensor.
- Damaged crankshaft position sensor.
- Clogged pipes or exhaust gas recirculation valve.
- Clogged catalytic converters.
- Damaged air flow sensor (TDI).
- Damaged throttle position sensor.
- Leaking cylinder head gasket.
- Low engine compression
- Poor fuel quality.
- Faulty PCM.

Pathfinder7

I admit I did the oiling and it was pretty heavy. It's definitely everywhere even after cleaning. I just picked it up and I see evidence of it all over the place, especially down the passenger side bank where it dripped out of the airbox. It's definitely the BMC oil, though I'm unsure if that's causing the issue.

The intake is stock otherwise. I'm not sure they were capable of a full system scan. When I drove off, I received another malfunction of the auto start/stop system.

I can also feel the misfire or retarding. It comes on as a hard stutter under 25% throttle or more. It also feels like it just misses when cruising at steady and low speeds. It's home and not moving until I can contact the other shop.