A idling issue! - 986 Forum - The Community for Porsche Boxster & Cayman Owners

blinkwatt · 12-20-2005, 11:10 PM

Now when I start up the car and let it warm up it idles fine just under the 1k mark. But ever once and and awhile when Iam at a stop light or am just idling after I have left the garage the car drops around 200-300 rpm and the radio temporarily shuts down for about a second and everything is fine. It is almost as if the car has a hick-up or burp of some sort. It doesnt do any sort of thing while im driving it or driving real slow just when idling. This has been happening on and off and it seems as the weather gets colder it does it more and more. Any help or input would be appreciated.

12-21-2005, 03:43 AM

blinkwatt, I posted this info a couple weeks ago. Possibly this can help you too:

"Usually the problem would be with a sluggish Idle stabilizer or also called an IACV. These valves can get corrosion in them and slow down until they get stuck and then cease to work. This valve controls the amount of controlled bypass air required to keep the car idling. These conditions change with load and the valve opens or closes to accommodate this. The valve is easy to access from its location on the side of the throttle valve housing. This condition will usually be exacerbated with the A.C. on.

Scott Slauson - PCA WebSite - 7/26/2004

A small drop in rpm's is normal when the A.C. operates. This is due to the load of the compressor turning on and off. Now there have been a couple of problems creating a drastic drop in rpm's with the A.C. switching on and off in the Boxster and 996.
The first is very simple, they were overcharged with 134a freon. This was done at the factory and often during an A.C. repair. An over charge of freon will cause an excessive load on the engine. This is simply taken care of by recovering all the freon and recharging it to the label under the hood. Depending on the year the charge rates are different.
The second is the Idle Air Control Valve (IACV). These valves tend to get corroded and they stick. Under normal running conditions they move very little. When the A.C. is turned on they are required to move the most. They will give you an erratic idle and sometimes even stall the car when completely bad.

Scott Slauson - PCA WebSite - 5/5/2004"