987 Gen II, 2.9: rough idle, something to worry about?

[911hillclimber]

As title, car has FSH and 33K miles.
Goes really well and can give 37 mpg, Shell Nitro 98 ron.
Idle after a minute or less, hot or cold is lumpy with rev counter varying +/- 200 rpm. This action never changes, always 'rough' and will shake the whole car slightly....
Lumpy as if it was fitted with a 'racing' set of cams.

It sometimes will give a very light whiff of oil smoke on cold start after sitting for a few days or more on level driveway, clears in seconds.
Dash oil gauge shows right oil level.

Just done a 2 week/2000 mile road trip to Switzerland with zero problems.

So...should I be worried?

 

[C2dweller]

It doesn't sound normal - I would recommend a diagnostic test, which can be performed at any Porsche specialists / OPC . There will probably be fault code which will shed some light On the issue.
KR Lee

 

[CLIFFWILKINS]

As above good idea to get it plugged in to a diagnostic to get a read out.
You can try cleaning the MAF
Can't be petrol as you are using shell nitro 98 ron
Smoke on start up after a lay up is pretty normal lots do it some do some don't.
If your not far try Jaz in St Albans Steve is the Boxster Register Technical Mechanical Advisor
Cliff.

 

[911hillclimber]

Thanks for the replies.
Spoke to the Indi specialist where I bought it from who were helpful.

Gen II 2.9's 'all' do it.
Still have 3 months warrantee....

 

[stephenbailey]

Hi
Totally agree, diagnostic the best check , I think it sound like one or more coil packs damaged
One of mine was damaged and I experienced the same symptoms with my car

Hope this helps
Steve

2006 Cayman S
LANDS

 

[Motorhead]

All of the above Graham plus it could be a faulty crank position sensor. A diagnostic check should indicate if this is the case.

A lot of white-ish smoke on start-up would indicate an AOS failure/impending failure which could contribute to a rough idle, but this seems unlikely in your case judging by your description.

Jeff

 

[911hillclimber]

Thank you, car runs great other than this lumpy tick-over.
Car never stalls, starts stops well and no nasty noises.

Will find a closer Indie to me than the seller.

 

[ThreeTwo]

Get the car on a Porsche diagnostics as soon as you can. They don't 'all do that' so it would be wrong to not get it checked. Coil pack is the obvious and easy to sort... What region are you?

 

[Neil Haughey]

I am going through similar on my Megane, its seems on all modern cars the cause is one of the following: dodgy or dirty injector/s, crank sensor, coil pack.

 

[911hillclimber]

I'm in Region 13
Car came from PCT, but I know an Indie in Cheltenham with the kit.

 

[tscaptain]

I'm surprised PCT haven't agreed to get it looked at under warranty. I bought my Cayenne from there and they were excellent when I had a couple of "issues" during the guarantee period.

 

[andrew ish]

Had what sounds like the same problem on my 986S which turned out to be the variable valve actuator sticking on one cylinder bank which resulted in the timing being out at idle. If it is this then reading out the fault codes will tell you. I can check which code if it helps. Not an easy or cheap fix so certainly worth resolving before your warranty expires.
Andrew

 

[ThreeTwo]

PM sent...

 

[911hillclimber]

pm replied to, thanks.

 

[911hillclimber]

Had a lot of white/blue smoke on start-up a few days ago, 3rd time and again but much more this morning.
Car stood on level ground, 3 days between running the car.

Oil level 1 bar blow the top as it should be, engine uses no oil.

Tick over getting rougher, so with electric speed, the supplier is taking it into the workshop next Monday, leaving it there for them to take a good look.

 

[Motorhead]

Graham,

As I said above, a lot of white-ish smoke on start-up is generally attributed to an AOS problem. You could try removing the oil filler cap when the engine is idling. If the AOS is faulty, the oil fill cap will be hard to remove because it is under excessive vacuum. If the AOS is in good shape, you should be able to remove the cap without much resistance.

Jeff

 

[ThreeTwo]

pm replied to, thanks.

PM not landed with me...strange... but you can contact me via the contact page on the address I gave....cheers

 

[911hillclimber]

I'll wait and see what PCT say after their examination in their workshop.

I hope it is not bore score and will be the AOS. I'll try the 'vacuum test' on Monday.
I'm reluctant to use it now until this is totally solved.

Deflated my modern Porsche bubble a bit, so hope to be back together soon.

 

[Motorhead]

Probably best not to use the car Graham - oil traces in the inlet ducting and exhaust aren't good for the MAF sensor and cat converters.

Hope it's something simple (and inexpensive) to fix and you can get back to enjoying your car.

Jeff

 

[911hillclimber]

Hope you are right!

Just got the wife to start the car, same spot on the drive when it last belched smoke and 3 days or longer since last used.

Camera ready for the cloud, and nothing. Typical!

Did the engine oil cap off test and the suction is very marked, the cap had to be pulled off rather than lifted off against a small resistance.
Thus, I hope it is a new AOL and a new crank sensor though i'm sure I've read the AOL issue can give rise to a rough idle(?).

Over the phone, car unseen the first response was a duff temp sensor, but that seems very unlikely.

Monday and the next few days will tell.

At lease PCT have a good reputation.
Are 2.9 engines prone to scored bores, but if one/they are, then blue oil smoke would prevail on every cold start-up? (or ordinary running)

I have a '73 911 with a 1985 3.2 in it, now 130k miles old, and sometimes I get a whiff of blue smoke on start-up, but this is like a steam boat funnel at times, but does not last long.
After 4 seconds or so it has stopped coming from the exhaust, just a cloud over the rear of the car and the surrounding air.
Videos I've seen of a 'typical' AOS failure is a dense white smoke for ages.

Still worried!