DC911S

I was getting a rough idle at cold start and even warm idle was a bit off. So I removed the TB and it was very dirty! Even the blade inside it was dirty. A good scrubbing with CRC TB cleaner and its al back together and running smoothly. For others as a reference, Its a 2009 C4S with almost 40K miles on it. I got it a year go from Carmax. I drive to pretty hard but the previous owner babied it. Note that there is no way to really clean it unless you take it all the way off. Its not hard to do. Take the airbox and rubber connecting hose to the TB in one piece. Then take the TB off. All you need is a 20 mm torx socket and a 10 mm regular socket. This is not a regular item in Porsche service, not sure why not. I guess they want you to buy a new one. Also remember to do the TB calibration routine via they Key on/off sequence one its all back together.

Airbag997

I was just in there not too long ago when I changed out the serpentine. Mine was as clean as a whistle (09 C2S). Never had to clean it. Maybe the previous owner neglected to replace the air filter elements often enough.

platinum997

Was the airbox side dirtier than the plenum side? Would be good if you could tell if it needed cleaned without removing.

Any gasket in between that needs replaced?

DC911S

The plenum side was dirtier. It was black right behind the blade for a good 1/4 inch or so. The blade edges were dirty as well with some sort of black material. I used CRC to soften it then a cloth to get it off. In front of the blade for about 1/16 of an inch it was dirty. Not sure how it built up behind the blade. It was dry, so it’s not the AOS failing. Must be due from blowback off the valves coming up. I changed to BMC filters last fall and the paper ones I took out were not in bad shape.

You could use a flashlight and open the blade up to see behind it to look for the black stuff. But it’s just four bolts to take off. You still need to remove the hose that connects the TB to the air box to look inside.

platinum997

Makes sense.. thanks. Will look sometime this week.

Dartmouth

I'm still expierencing rough idle and rpm fluctuating at idle speed even AFTER having the throttle body cleaned and boot replaced. Now the independent says there is nothing else to do and to live with it.
It's driving me crazy. Idle is up and down from 500 to 800 rpms approx., all the time. I need some suggestions how to get the idle stabilized!

platinum997

I just completed this weekend. Mine wasn't dirty at 31k but cleaned anyway. I didn't remove though. Just put the key in the on position and have someone hold the gas peddle down. She opens right up for you . No calibration needed that way.

bgrpph

dartmouth- try runing a can of chevron techron in tank of gas- get the concentrated one- it helped with my previous 996C2 with slight rough idle. can't hurt- some say use it in tankful just prior to changing the oil.

cvtbenhogan

New plugs worked for me. Dead flat idle now.

DC911S

feel around the hose connecting the TB to the airbox and make sure the clamps are tight. It’s easy to have the bottom which you can’t see not be fitted properly on both ends. You sort of have to feel under there to make sure it’s seated correctly.

Myren

I usually just spray some arb cleaner or brake cleaner into it sometimes. Don't doo too much, don't want to flood your engine

Bruce In Philly

Interesting you say it is not standard P maintenance.... as you found out, it should be.

I had, at the time, the 2nd highest mileage Porsche my local dealer had seen. My 2000 Boxster S was leader in things going wrong with these newish engines and chassis..... My dealer did quite a bit of diagnosing with me in the bay trying to find that rough idle.... swapping MAS sensors, no codes... etc.... Finally he just starting shooting spray in there and voila...... smooth idle.

I cleaned the throttle body of my 2009 C2S at around 40K miles too..... jammed a soaked rag in there and it came out BLACK.

I clean it when I change my air filters as simple preventative maintenance.

Peace,
Bruce in Philly

DC911S

Yes I think at times the simple and obvious solutions are missed by supposedly smart people. All this talk of swapping out and cleaning the MAF sensor and being puzzled by lack of codes popping up with a rough idle, can least at first be checked by cleaning the TB. At idle position the TB blade is not opened much and the black soot buildup can mess up the minimal airflow in that position airflow. I think what happens when the TB barrell is gunked up is that the TB blade quivers to adjust the airflow and hence you get the fluctuating idle. But yes, good thing to do it when you do air filters.

Greyghost230

I thought that manually opening the TB could result in codes and confusing the computer.
Anyone have issues with this?

platinum997

Thats my understanding as well. Most drive by wire systems are this way. That's why you need to do the calibration.

Or just open with the gas peddle.