Very rough idle on startup

[jas142]

If the car has been sitting for awhile, like overnight, or when I get out of class or work, it has a REAL rough idle while in park. It'll variate between 500 and 1000, and its so rough that it sounds like its been CAMMED! Somthing serious? What do ya think it is?

 

[Monkie]

Mine does that sometimes when it has been sitting for weeks. If I disconnect the battery and make the computer reflash then it also does it.

 

[Go HoTO!]

Man, that could be a zillion different things. I suffered from the SAME THING since I owned it. But, replaced the IAC and installed a custom tune from SCT and the problem went away. It used to only do that for secpnds to a minut or so, so I just used to deal with it. Try cleaning the IAC. Takes only a few minutes and it can't hurt.

 

[jas142]

Where is the IAC located and how would I go about cleaning it? Thanks

 

[Dark Knight GT]

Most Idle problems are caused by a dirty IAC. Using some carb cleaner to clean it might clear the problem up. It's also normal for the car to idle a bit "high" when you first start it up when its been setting for more than a few hours because the computer is programed to due so to get the fluids pumping and get the car warmed up quicker. So that might be all it is. If you want to have more info. on the IAC, do a search or just wait patiently till someone who has a pic of the IAC posts it. I can describe it though for now. Its a little valve looking piece on the front of the upper intake(the part with the pony on it). It's held in place by two bolts, a plastic electrical connector, and it also has a hose attached to it that extends to the intake tubing. If you know what the PCV is, then you can find the IAC real easily. The PCV tubing attaches to the intake tubing right next to the IAC tubing. Trace that tube to its source and you have the IAC.

 

[stang2001GT]

I just bought a new IAC from AutoZone for $60. I am going to install later this week. It is located on front of the plenum (has the pony logo on it) It has an electrical connector and a hose attached to it. You have to take both them off and it is only bolted on with 2 bolts. From what I hear on here it only will take 10-15 minutes to swap, and by the looks of it, it can't take any longer than that. I hope that is the problem for you, and it gets fixed. Good luck.

 

[stang2001GT]

wow, I think we wrote the same exact thing at the same exact time. lol

 

[stang2001GT]

Here is the best I can do in 5 minutes. It is inside the box. Can't see much, but now you can go look on your car.

 

[Dark Knight GT]

wow, I think we wrote the same exact thing at the same exact time. lol

Techinically not as my post came in 1 minute sooner.

 

[triggz]

My car almost always idles rough at cold startup since I installed NGK spark plugs (vs autolite coppers). I could floor it and the car would almost die sputtering. Takes only about 10 seconds to clear up though and seems to run better with them overall past that.