97 rough idle fixed

[sparrowhawwk]

Well, after reading a bunch of posts on fast idle issues I decided to check the spark plugs first as it is a new to me vehicle and I'm not impressed with previous maintenance. I work with a friend that has been an auto tech all his life and he said the plugs looked ok and he doubted changing them would make any improvement. I told him I was going to get some contact cleaner and clean the IAC. He mentioned he had cleaned lots of those over the years but just used carb. cleaner. I figured worse case I would change it so I grabbed the carb cleaner and used it. A fair bit of black came out of the unit but I noticed something interesting. Under the little black cap mine has two what appear to be felt discs. Both of these were packed solid on the one side so that obviously not much if any air was getting through. I shot a little cleaner into the can lid and tossed them in for about 10 or 15 seconds and then dumped them out on a clean paper towel. I think as much black came out of them as out of the valve.
Mine never had a starting issue but the idle was getting progressively worse and it was starting to stumble at lower rpm around town. I have put about a half hour driving around town on it now and it seems to be fixed.

 

[koda2000]

that makes sense. the valve meters air into the intake (as dictated by the ecu) to control the idle. air gets sucked in under the little cap on the IAC. the felt disks act as filters, if they get clogged it's difficult or impossible for air to get through.