I have an 06 Civic and I have been having problems with the engine idling up to 2-3000 RPMs when I put it in park. It doesn’t do this every time when I put it in park but I would say at least 50% of the time. I noticed that if I sit in my car that it will continue to idle high, but if I open the door and get out it immediately idles down to 1000 RPM or lower like normal. If I shut the car off in the middle of it idling high and get out and restart it then it starts up completely normal. The air/heat on the drivers side comes and goes randomly and sometimes the brake pedal is stiff when I press it and I have to force it down to get them to work (pads and rotars are in good shape). I also have problems when I come to a stop with the car coming down through the gears slow but it has been going on since August at least so I would think it if was a transmission issue that it would’ve went out by now. The check engine light has never come on. My mechanic thought it originally was the throttle assembly so we replaced that but it didn’t fix the problem at all. I am not sure what the problem is. Any help would be much appreciated! Thanks!

 

It sounds like you have a vacuum leak somewhere. Thats what it sounds like from your description. What you could try doing is taking THROTTLE BODY CLEANER OR CARB CLEANER. Spray it around all the vacuum hoses. And if your car changes idle after spraying either or spray on the hose joint then its a vacuum leak. Now im not sure what your knowledge is with cars but if you know were the hoses are then it will be easy. If not you should be able to Google image the location of the vacuum hoses.