indling problem when the engine is cold

[porsche356]

hi all,

My 997 2s (2005) has developed a new habit. When I start the car, with a cold engine, my stationaire idle rpm changes constantly between 900-1100 rpm's. I guess this has to do with the choke (cold engine injection), but I have no clue where to look.

Problem is gone after driving the car for a bit (no choke)

Any ideas?

Regards, frank

[RFM]

I would start cleaning the throttle body, and see if there is a change in cold RPM behaviour. As long there is no fault code on the dash, and there is no diagnostic tool available to read out the DME in "Actual Values" mode, it still a guess.

[porsche356]

Hi RFM,

Thanks a lot for the reply. I will try cleaning the throttle house first (as soon as I figure out how to! Any advise/pics? Can't find it on the site). What material can I use to clean the throttle house? Do I have to clean the MAF as well?

Regards, frank

[RFM]

http://www.renntech.org/forums/index.php/tutorials/article/59-diy-throttle-body-cleaning/ it's a 996 DIY but is essentially the same as 997. There are special MAF cleaning products on the market but have not my preference associated with the production process of a MAF, anyway you are free to try it. Success.

[porsche356]

Did the job yesterday:

Great result; problem gone.... nice idle AND a complete new car. The throttle response is 'scary'.... the engine sounds much better en drives like new.

There wasn't that much carbon on the throttle (car was serviced a year ago (<10K km), but the changes are huge.

Very easy to do and highly recommended. I will definitely do this every 6 month.

Thanks a lot.

Tried to do the same on my wifes cayenne turbo (2008) but got stuck. I wasn't able to get the 'áir' hose from the throttle house. There isn't a metal ring holding the air housing on the throttle house. Any advise on how this should be done? Taking off the complete housing isn't very easy because 2 screws are by far out of reach.

Thanks a million,

Frank