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Interesting. My 2015 base has the -06 suffix p/n with no o-ring and I can't say that I have the problem with acceleration. I'll probably spring for the updated -08 p/n just to see if there's an improvement. It appears though that just the o-ring from the 718 would fit as both use the same filler tube p/n. There appears to be an o-ring description. (26,50 X 4,00), but it doesn't make sense to me. Cross section of 4mm would make sense, but the 26,50 doesn't work well for diameter.
Wow. I would never have known. I am the original owner of my 2014 BS and got it in July 2013. The engine stumbling issue always bothered me. I just checked my car and it does not have the O-ring either.
Going to buy a new one and see how it works. I just ordered the oil cap from Suncoast parts.
Last edited by subshooter; 12-30-2023 at 12:45 PM.
The parts catalog says the -06 one was dropped on 8/16/2019. Definitely after the 718 models were in production. So it's possible there are 718 cars with the 06 one...
The o-ring is not on the diagram for the 981 models but it is for the 718 ones. Odd stuff. Omission on purpose in the 981 models or an accident?
Same cap, same filler tube.
I've been thinking about this more and even though the O-ring appears to fix it, this doesn't really make sense. The oil ring wasn't there when the car was new and I can't imagine the new cars had this issue.
I've been thinking about this more and even though the O-ring appears to fix it, this doesn't really make sense. The oil ring wasn't there when the car was new and I can't imagine the new cars had this issue.
I don’t think it’s a 100% fix. It’s made the issue imperceptible in daily driving. I have driven about 1000 miles since then I think.
maybe it’s a combination of things that feed and control the variocam and there are other parts that need replacing.
Or it’s a software thing and it is what it is.
But to your point about new cars..I think some cars did have it.
and it also doesn’t explain why the 991 has this issue. Diff oil cap right?
but hey! Try a new cap for the 981. Not thaaat expensive in the grand scheme of things and low level of effort.
Perhaps I am wrong, but why would the oil cap missing an O ring cause a vacuum leak? Isn't the crankcase under positive pressure when the engine is running? Positive crankcase ventilation systems work to vent this pressure into the intake manifold. The oil vapors are burned, and this is what causes buildup of carbon on intake valves on direct injection engines....
Perhaps I am wrong, but why would the oil cap missing an O ring cause a vacuum leak? Isn't the crankcase under positive pressure when the engine is running? Positive crankcase ventilation systems work to vent this pressure into the intake manifold. The oil vapors are burned, and this is what causes buildup of carbon on intake valves on direct injection engines....
no clue but there was a difference in reading on the manometer with a cap that had a oring and one without.
I checked the cap on my '14 CS after reading this today and noticed a small amount of oil on the top of the cap itself and on the inside of the cover. My cap is missing the O-ring, so I ordered a new one from Suncoast. I last changed the oil myself a month ago and the cap/surrounding area was clean. The crankcase is normally under slight pressure from blowby while the engine is running, thus the PCV system. You might want to recheck this and/or check the manometer. It is interesting that changing the cap made the car run better. One hypothesis is that the PCV has failed completely open and is feeding way more crankcase gas to the intake than it should, causing vacuum and thus hesitation?
I checked the cap on my '14 CS after reading this today and noticed a small amount of oil on the top of the cap itself and on the inside of the cover. My cap is missing the O-ring, so I ordered a new one from Suncoast. I last changed the oil myself a month ago and the cap/surrounding area was clean. The crankcase is normally under slight pressure from blowby while the engine is running, thus the PCV system. You might want to recheck this and/or check the manometer. It is interesting that changing the cap made the car run better. One hypothesis is that the PCV has failed completely open and is feeding way more crankcase gas to the intake than it should, causing vacuum and thus hesitation?
Good luck.
I did smoke test the car and there was no other leaks.
When I changed the MAP sensor, I saw some oil in the intake but folks said that's normal..?
I also hear a pulsing sound from the tube that's connected on the top right after the throttle body.
btw, I bought the manometer to check the AOS...and I did consider maybe the PCV had something to do with it. But I kinda stopped chasing 100% fix because the cap made a diff.
I took some measurements of the oil cap and settled on 73x4mm (IDxCS) for the probable size of the o-ring. It was about $8 shipped for a 3 pack on eBay. Will update this when they arrive.
12-30-2023, 08:41 AM
