fester

Got my 991 4S 4 years service from dealership and since then have a very annoying issue that they say "is ok unless there's check engine light".......the idle is NOT smooth. It constantly revs up and down in 200 rpm range no matter whether the engine is hot or cold, in gear on park etc. On the service Mgr suggestion, I've switched between chevron and shell v power but there's no difference either.

I'm perplexed since there's no solution offered.

Any thoughts or remedies ? Anyone experiencing such issue? It only had 20K miles at the time of service...

Video clip attached

Hula

Did you try a fuel system cleaner? Chevron and Shell use different detergents. That's the only reason I can think a dealer would recommend switching. The gas is the same. Shell adds Nitrogen. Chevron uses Techron. Techron is a proprietary blend of polyethylene and kerosene. You get small amounts when you fill up but you should try a concentrated additive.

Chevron owns the patent and sells consumers small bottles of Techron fuel system cleaner. Techron works but I recommend 44K Fuel System cleaner sold by BG. BG is licensed by Chevron to sell to industry. The bottle of 44K they sell to industry is the same except has a higher concentration of the detergent. https://goo.gl/Uz87zr

Other that that, dirty throttle body?

CSK 911 C4S

The little vid to me shows normal needle movement.

Mine has done this all the time and the difference in engine sound at idle is undetectable.

captainkirk

Try a Indy shop who specialize in Porsches

worf928

That is totally normal.

R_Rated

May be a coil? Mine was running a little "off" and come to find out cylinder 3 was off. PDK is crisper and exhaust sounds way better now.

Dbull65

Sounds normal to me as well.

JW911

That is normal and that is not a 200 rpm variance. That's about a 50 rpm variance.

Hurricane

Normal.

Grunty

Totally normal. That's just your cars way of being impatient with you and wanting to be let off the leash.

Dewinator

When you're cruising at a steady speed with cruise control, does it kind of surge and waver a tiny bit as well? And sometimes jerky starts from a stop? If so you're in the early stages of a failing throttle valve. If that's the case, don't worry because it will get bad enough to throw faults after awhile. It's easy to see if you take the bumper and intake housing off, the valve will visibly waver even at idle.

Code

My car does the same.

GregD

I see a little variation in normal mode with a lower RPM, in sports mode the idle getsbumped a little bit and its more stable. Have you tried in sports mode ?