Gus_Smedstad

I think it's still worth checking the clutch before assuming it's an engine problem that's just appeared.

The last time I had a car which needed a new clutch, the obvious indicator was that the tach wasn't steady when cruising at a steady speed. It tended to fluctuate up and down. Probably your best check is to take it up to high gear on a highway and see how it behaves.

subshooter

I've had stumble since day zero. It was always there. Is the stumble only in 1st gear between 2 and 3k rpm? If so, I wouldn't suspect the clutch. Many people have their clutch last well over 100k miles. Your car is still low mileage in my book.

Although I agree that it is odd that you had not experienced the stumble before. It is normal.

Needsdecaf

I just did a 50 mile round trip last night on the highway. Did not detect any behavior like this at all.

So I just took it out for a drive, in both Sport and normal modes. I really only feel it in the lower gears. I'm thinking it's almost more of an exaggerated driveline shunt. I don't get it at all in 4th gear or up. And if I am really, really smooth from 2k to 3k, I don't feel it at all.

If I put it in Sport, it's almost non-existent.

I wonder if it's an active engine mount going bad? Or the trans mount failing?

996_soon

I also experience this on my 15 C2 MT w/12k miles. I'm bringing it to the dealer for the 2yr service and will bring it up to the SA. It's hard to believe it's normal. Didn't have this issue with my previous 997 tt.

Gus_Smedstad

We've had two (2) active engine mounts go bad on my wife's 2015 Cayman S, and didn't feel a thing. In both cases the only reason we knew there was a problem was that the multi-function display popped up the PADM error. I'd assume if you can feel such a thing, it would wouldn't depend on gearing, but on engine RPM.

wwspeeds

So I have a 2013 C4S MT. I've driven it 22k miles now. around a year ago, I had this weird pause at low RPMs as well. It was very clearly there. It sounds similar to what you're describing.

I had been putting a lot of low RPM miles in (putting around town). So I put in a few really hard drives on the highway, WOT, pulling hard (with appropriate coolant and oil temps of course). Maybe 20-30 miles. Within a few days, that pause disappeared.

I always drive in Sport Plus mode. I have PSE.

Perhaps it's some kind of software accommodation to your driving style?

give it a shot and get back to us!

W

Needsdecaf

The Italian tune up. I may do this as well.

Highyo

Decaf your luck is rediculously bad. I remember the f10 drift

Archimedes

My question for you folks who have the stumble, do you notice it when your driving your car normally or do you have to specifically run it slowly through that specific rev range to get the stumble?

On a related note, wasn't there another thread on here where someone recently (within the last few months) mentioned a fix they found? I could have sworn I read someone posting about chasing this thing all over the motor and finally finding something that had been installed wrong, IIRC two electrical connectors that were swapped during install at the factory.

K-A

Needsdecaf! Man, was reading this thread and didn't even realize it was you! Sucks to see you're being met with this after moving from the F10.

Any link or quick description of what this "stumble" is? I'm assuming it's not a catastrophic failure type of issue, more so an annoyance (i.e not something that will break the car, but something that affects the way it drives).

It only related to 991's or also 981's?

Needsdecaf

Yeah...the pull to the right that required a new steering column. The constant drifting while driving straight...no wait, that's BMW's EPS doing "wind correction". The terrible Bluetooth mics. The 250 RPM idle surge, the ridiculous Nav, and finally the nasty throttle tip-in lag that more than once almost caused me to get into an accident. That ultimately lead to me to getting rid of the car. Compared to that, this stumble is a walk in the park. That was downright unsafe.


The nav....there just are no words to describe how stupid it was. So I will let the pictures do the talking.

Like this one, that tried to get me to pull a u turn.....in the middle of a divided road.



Or this one that thought driving 1/4 mile on the highway wasn't fun, so it wanted me to get off, do a u-turn, and get back on.

pfan

I notice the stumble in two instances:

1) Normal driving under light throttle. Around town, as I accelerate through ~2600 rpm I'll get it. Occurs probably 75% of the time. For some reason, it never occurs in 1st gear. Drive it aggressively and you'll never feel the slightest hesitation.

2) On an uphill grade, if I hold the rpm at or near 2600, I'll get a noticeable stumble. Imagine a micro second of bad fuel.

Chances are, if someone else were to drive my car, it would take a week or so for them to notice the problem. But once you know it's there, it's impossible to ignore.

dd356

What models has the "stumble" been reported on? 911 and Cayman only?

RobC4sX51

May 22nd! Actually got my car back May 15th after it being at the dealer for 2 full weeks. That was the 3rd time I brought it in since installing the X51 in Dec 2016. I reported on May 22nd that my car was fixed and no longer had the stumble, or hesitation. Mine was caused by a crossed wire connector. See below. Obviously not the fix for everyone. My car has been awesome for over a month. Sorry to hear about this. Good luck.

Needsdecaf

Pfan's post below is a great description of what I feel.

That "fix" was an issue with the PSE plug and something related to the coolant being swapped. That member had his PSE installed after purchase. What he was experiencing was likely different than the stumble, and caused by the install.

Good to see you on here! There are a ton of Bimmerpost members on here.

Below is the best way to describe what it is. But if you want a huge reading assignment...https://www.6speedonline.com/forums/...-2500-rpm.html