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 or on park etc. On the service Mgr's suggestion, I've switched between chevron and shell v power but there's no difference either.

I'm perplexed since there's no solution offere

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

Video clip attached

 

After 4 years I would not touch this . The deviation is so slight and I haven't even looked on my current car but have seen mild fluctuations on past Porsches . To hope for a 100 percent success flat line idle is optimistic but with all the variables its not likely . Factors like climate. fuel, altitude , even the AC or heat can sway that needle .

 

I also have a rougher idle and it fluctuates a bit. I'm at 18,500 miles and 4 years exactly (in fact my warranty runs out tomorrow).

When I put it in Sport mode it's pegged at 800 exactly, but in normal mode it hunts around from 600 to 700 sometimes.

This was another thing I mentioned to my dealer when dealing with the hesitation and stumble issue. Everything was considered "normal" since no codes were thrown. Welcome to car service with modern cars! Unless the computer says so, there is no problem. It's all in your mind.

 

Any issues when taking off from a stop with the engine cold in regular mode? Any issues on inclines when cold either?

 

After reading this, I checked my 2012 991 C2S with 11k miles and when the engine is cold, I see the same rpm fluctuation as you on idling. I never really noticed before.

After the engine and oil gets to normal temperature, the rpm fluctuations goes away. The outside temperature was around 80 f when I tested it.

 

2013 4S
I've noticed it all along, never thought it was a problem or anything, I'm gonna keep ignoring it and making it an annoyance.
Mind...over...Matter...lol

 

I had erratic idle, on my previews 991 not normal to me, same BS from dealer, now on my other 991 idle is solid steady

 

That doesn't look like a "200 rpm range" deviation to me.

I don't have the specs for the newer models but idle speed for say my 2003 996 Turbo is 740 RPMs +/- 40 RPMs. I would expect the newer models to have the same spec though.

Not sure if the newer models "require" this but look into your owners manual for an E-Gas calibration procedure.

If you find one my advice is to do it as per the directions.

(Should read something like this: With the key off and your foot off the gas pedal turn the key to the on position and leave on for at least 60 seconds. Then turn the key to the off position and leave off for at least 10 seconds. The next time the engine is started the calibration is done.)