2002 Dodge Ram 5.9l Automatic

My truck for a while now (couple of months) has been idleing up and down when I first start it in the morning. It only does it when I first start it in the morning, and does not do it anymore during the day. When I put it into drive or reverse it will not do it then. It idles where it is suppose to when in forward and reverse. It only goes up by +or- 600 rpm. It is not a lot of difference. It usually bounces between 900 to 1500 rpm. I do mean bounces, it will not stay up at 1500 soon as it gets there it will fall back to around 900 rpms then back up and then down you get the picture. Then I put it into gear and it falls down to where it is suppose to. the truck still performs great. Like to get this resolved.

 

could be a few things. PCV valve, IAC valve, vac leak, in need of a tune-up.

 

Thank you dirtydog. I was thinking IAC Valve but not sure of myself. Now I have some places to start looking at or replaceing. Anybody else have anything to add.

Question > is threre a valve and/or sensor that controls the idle when started cold and then lets it lower when the vehicle warms up. (it may be the IAC Valve)

 

It's the IAC valve. It allows air to bypass the throttlebody to maintain a steady idle. I would remove it and spray it with some brake cleaner. it's prob all carbon'ed up.

 

i had a 02 Durango that did that, it was the IAC valve. cleaned it and that solved the problem.

 

Thank you fellars I will clean the IAC valve this weekend and will let you know if that works.

 

can somebody taea picture and show me where thats at, or tell me and describe it... i have the same problem! thanks

 

having the same problem but does it only once in awhile and has only done it a few times but if im sitting at a light or park in a parking lot it sometime will bounce from about 500 to 1000 rpms. i have a 2002 4.7 and would like to know where the IAC valve so i can give that a cleaning and see what that does, hopefully help.

 

bump......