I have an 05 997,(recently bought, and my 1st liquid cooled 911!) and just had my car in for the 60k major service. On the way home from the shop I noticed a vibration in the seats and a "wiggling" tach (+or- 50 rpm) at idle.
Plugs / coil packs and the drive belt were replaced as part of this service.

The issue is less noticeable when the A/C compressor is running as this seems to boost the idle RPMs up a bit which smooths out the idle. There is no other noticeable shake any where else in the RPM range. Power is even and smooth all the way to redline.

I took it back over to the shop the next day and they used the factory piwis to try to diagnose the problem but to no avail. No faults had been logged. They also performed a number of diagnostics with the piwis and everything was within "normal parameters". Also the rear motor mounts were checked and still very tight.

Let me also mention for completeness that the car has an Evolution Motors cold air intake with a dry filter and superfine mesh filter cover, but again, the idle was fine before the service.

Any guidance thoughts on this thread would be greatly appreciated.

 

sounds like coils to me. Did they make sure to put it back in order? or maybe not seated well?

 

Yes both of those things were double checked and no faults were logged.

 

hhhm, mm, i wonder at the coils also, i see a bit of roughness with cold idle and a porsche tech at PZ køln leans toward them as like the first place to look with idle issues when they are a bit old... and is there a way to check them? i haven't asked him that ... yet...

 

Its not a cold engine issue. It occurs consistently at any operating temps.

Since there are no faults being being thrown, it seems the only way to check them is to swap them all out or one at a time with news ones and see if the problem goes away? The other alternative is to just drive the car until a CEL comes on, but who knows how long that will be...if ever!!!


I was told that there were some MAF sensor problems with the aftermarket CAI but I'm guessing that was due to using an oiled filter element. But there is a dry filter on it now and I haven't seen any faults related to the MAF. I do wonder if there might have been some kind of piwis programming change performed related to the aftermarket CAI that was somehow reset when the plugs / coils were changed, but I' haven't found any posts about anyone needing to do something like that with an aftermarket CAI.

 

Silly question and probably silly recommendation, but have you tried resetting your system (unplug battery)?

See if the ECU needs to relearn the fresh tuneup.

 

Hmmmm. Not silly at all. No one has mentioned that yet. I'd have to check to see what kinds of resets might have already been dome as part of that service after plugs / coils replacement.

Any idea what else would get reset or lost in the process and how long would I need to keep the battery disconnected?

 

Some do the disconnect for a few minutes; others do it for an hour or so. There's also a thread on how to "reset your throttle" using your key and counting the seconds here; I just couldn't seem to find it.

Did they also clean your throttle?

Also, don't discount that you have bad gas also. You may want to add Techron now, once empty, ensure you buy good gas.

Lastly, when disconnecting the battery, you also need to reset your windows; they don't reset automatically. Don't freak out on the PASM messages; they will reset once you start driving.

Do a search on "throttle".

 

I had something like this happen after an oil change- it was caused by the oil cap not being on tight and allowing air to enter, per the dealer. Tightened it and voila'.
Best

 

[QUOTE=marcolum;4166962]I had something like this happen after an oil change- it was caused by the oil cap not being on tight and allowing air to enter, per the dealer. Tightened it and voila'.
Best[/QUOTE

This is interesting. No cel?

 

Nope, just a rough idle whenever I stopped of the way home, and no issues while at highway speeds. Once I got off the highway, I called the tech at the dealership, and he knew right away what was up. No lights, just gave him a description. Tightened the cap about 1/2 turn; it was gone as soon as I restarted, and has not returned, although I have taken care to keep the cap on tight since

 

I tightened the cap with no effect. I also removed the EVO V Flow CAI ( which I am selling BTW) and replaced it with the factory air intake and new OEM filter. Cleaned the MAF censor and throttle body as well.

I now have to believe that it has something to do with the new coil packs and plugs that went in as the problem started occurring immediately after that service. Even though there still are no error codes being thrown, maybe the there is something related to one or multiple plugs or coils that is just out enough to create a rough idle (plug gaps??), but not enough to throw an error. It guess it will need to go to the shop and have them look at the readings in detail with their piwis and hopefully they will figure out what's going on.

 

Had the rough idle before and made a big fuss out of it. I had too as it was still under warranty. Dealer cleaned tb, cleaned injectors, no change, i replaced plugs, slight change, cleaned maf, still same..after 3k km....it just disappeared! Now idles like a porsche shoukd... Guess if there is no warning light....lets just be patient and let the car be...it will fix itself, and there is no cause for concern.

 

I've had this happen with bad gas as well.

 

Maybe your ECU was tuned in the past (are you the first owner?) and the tune was lost when a software update was applied to the ECU at the 60k service