For the past few weeks, I've been trying to track down a shuddering sensation that I'd been experiencing when braking to a stop. As the revs started to fall and the transmission downshifted, there was noticeable vibration felt through the steering wheel. At first I though it may be my transfer case acting up again, but yesterday I spent all day driving the car in different conditions and have narrowed the problem to something engine related.

When in Park, if the revs are slowly raised there's a noticeable vibration anywhere between 1000-1400RPM. Above and below those points the vibrations clear up and everything is silky smooth. Same symptoms when in gear and moving. Because these RPMs are used often in city driving, it's become annoying to the point where I'd like to address it if possible.

The only thing I've been able to pull up online have been a few people that Porsche told that defective downpipes were causing the problem. I find this hard to believe that all of a sudden these could just go bad after being bolted up for 5 years and 50,000 miles with no issues and no moving parts.

Anyone else dealt with anything like this?

 

You might mention that it's a base V6 since the V8 is likely to be completely different, and the new turbo V6's ditto.. (and diesel and hybrid..)

Just sayin..

 

Correct! 2012 Porsche Cayenne Base V6 with 53,000 miles.

 

My mothers 4.0TT Audi A8L was doing the same thing. Very strange but it turned out to be coming from malfunctioning valves in the exhaust system. Audi replaced the mufflers and it was good to go. Small chance it may be similar type of issue but i would not rule out it is an exhaust issue. Good luck

 

most likley motor mounts. They collapse and get the issues you describe. You can have tech check them and see if they are compressed a ton.

 

Seems to be a logical explanations, but on a 2012 with only 50,000 miles that's had an easy life? I've experienced shot motor mounts before in a few cars over the years, but it always affected NVH at idle and all throughout the RPM range.

And this only started happening a few weeks ago out of nowhere. I will certainly inspect them when I get back from traveling for the holidays and have the 958 up on stands to change the oil again--its due in about 1,500 miles.

 

I felt some vibration when the AC was set to max on our 2014 Cayenne V6. Took it to the dealer and they replaced the fan and motor mounts. Car only had 12k miles on it.

 

Well there goes my theory.

 

I had a chance to look into this issue further. After removing the bottom splash shield, and completing my oil change, I fired back up the car and had someone else slowly rev the car up in neutral. Absolutely no movement, except from the down pipes. As the RPMs hit certain points, the pipes would visibly shake. The motor mounts were definitely not the issue.

I've read a few other threads regarding this issue, and people were forced to get their down pipes replaced because the flex sections of the down pipes had become too weak to support the exhaust without vibrations. This would be fine if I were under warranty and could have Porsche handle everything, but addressing this out of warranty will not be fun. I wonder if there's an easier fix than removing the down pipes and installing new, more sturdy flex sections? Pretty disappointing in the build quality department that this would even be an issue on a car of this caliber.

The issue really isn't noticeable to anyone except me, but still bothers me enough that I'd like to get it address eventually.

 

Seems to me that I read somewhere that the base V6 has a slight imbalance around 1200-1400 rpms. I know mine does. Could this be the cause?

 

This could definitely be the cause. It's pretty easy to verify. Remove the one shield under the engine, have someone rev the car up slowly while looking at the downpipes from underneath. Mine visibly shake, pretty hard to miss as you rev the car up and let the RPMs fall back down. I'll try to get a video the next time I'm underneath there.

 

I have to bring my car in for service in April and i'll ask them about this. I have a warranty to 2020 on my '14 base. You don't notice it much while driving, but yeah-- would be nice if it was smooth.

Thanks!

 

Was there ever any final diagnosis on this problem? I am finding the same thing on 2013 Cayenne V6. I actually thought I heard a raddle as the car was slowly and the gears dropping down. Kinda like the vibration came in and then a brief raddle. Anyway, wondering if you finally figured out what the problem was and what the fix was.

 

No, mine is very minor, no rattle ever or shake. Just ever so slight imbalance. I'm pretty sure mine is inherent in this engine as I don't think it has a balance shaft. Should not impact longevity.

 

Sold the car a few months ago. Mine was 100% the downpipes rattling, and others have solved the problems with replacements, but wasn't worth it for me for how minor the problem actually was.