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Hi folks
Changed the O2 sensors last night.
The old sensors didn't look bad at all.
Installed the new ones and will be going for a drive this evening
Tear down..
Hi folks
Changed the O2 sensors last night.
The old sensors didn't look bad at all.
Installed the new ones and will be going for a drive this evening
My old sensors didn't look bad at all either. I see you also removed your spoiler - somehow I managed to do the job without removing that part. It was a tight fit getting the air box in and out that's for sure.
I see you also removed your spoiler - somehow I managed to do the job without removing that part. It was a tight fit getting the air box in and out that's for sure.
The more I work in the engine bay of this car, the more I'm convinced that Porsche employs Umpa lumpa's in their labor force..
Guys, I'm conflicted. I felt some stumbles in the usual places yesterday. :-(
Acceleration through 2-3K RPM is definitely smoother for me than before, but cruising at a constant 2300 RPM still had some stumbles present. I'm really hoping it was just the road surface playing tricks on me, or weird gas I had to get at a remote gas station while on a PCA drive yesterday.
I'll keep everyone updated.
P.S.- Did some charity laps around Summit Point main raceway - Felt nice to run around the track hitting 6-7K RPM Totally different car. We kept it tame since it wasn't real hot track laps, but still fun and spirited in a few parts.
Finally got around to driving the car last night and it's definitely improved the stumble.
The car is certainly more responsive, and the severity of stumble has improved considerably.
Here is the strange thing. On approx 20 test runs it would maybe do it twice, and not nearly as bad as before, whereas in the past it would do it every time.
Perhaps I'm now hypersensitive to this issue, but I will continue to drive it for the next week before passing final judgement.
On a side note, I'm due for a full service later this week (plugs, filters oil) so I'll have some time to test before the plugs get changed.
Regards...
Last edited by duxsi; 08-13-2017 at 08:41 PM.
Reason: typo
Perhaps I'm now hypersensitive to this issue, but I will continue to drive it for the next week before passing final judgement.
I think I'm in the same boat as you - hypersensitive now so I'm feeling everything... Definitely more responsive and much improved, but there is still something there.
I think I'm in the same boat as you - hypersensitive now so I'm feeling everything... Definitely more responsive and much improved, but there is still something there.
what you may be feeling is what is supposed to be there. There are a lot of cam shaft changes and air intake flap changes at those RPMs. The upsetting of the airflow causes some noticeable changes in the engine performance. The stumble was eight affect of those changes with the oxygen sensors that were out of whack.
Three weeks with the new sensors and I continue to be impressed with the engine's smoothness. Was really hoping the rest of you would see similar results. The very noticeable stumble at 2600 RPM appears to be gone, hopefully for good. After living with it for four years, it's an odd feeling to not experience it when accelerating under light throttle. I do notice what appears to be the Variocam changeover at about 2800 RPM, however it's very subtle compared to the previous sharp stumble. If things continue as is, I'm a very happy camper. My big concern is that the new sensors relearn the old bad habits.
I'm still confused as to the origins of the problem. I'm sure sensors can go bad over time, but many of us have dealt with the issue from day one of ownership. (Maybe a bad batch, or they're very quick learners). Additionally, why would a bad sensor be evident only at a specific RPM? The fact that the Variocam changeover RPM and the stumble RPM are very close makes one wonder if there is any cause and effect relationship. Today's engines and ECUs are so complex it's foolish for a layman (me) to even attempt to form a diagnosis.
I'm curious how common/pronounced this issue is. I'm looking into getting a 991 in the next year or two, and having test driven a couple, I never noticed anything like this.
I'm curious how common/pronounced this issue is. I'm looking into getting a 991 in the next year or two, and having test driven a couple, I never noticed anything like this.
08-10-2017, 11:20 AM
Totally different car. We kept it tame since it wasn't real hot track laps, but still fun and spirited in a few parts.
