masterofthepuppets99

so basically when i turn on my a/c or defroster my rpms fluctuate from 400-1200. this just started happening after i installed my c&l plenum. that or since it got really cold all of a sudden here and i never had idle probs in the hot weather, that it could be a cold weather problem but i seriously doubt it. i have an sct tuner and i have my idle set at 620ish and the car will idle perfect except when my compressor is activating. so im assuming that my iac is all messed up somehow. when i installed my plenum i was very very careful with that gasket and i dont think i damaged it. but i did notice that the rubber hose coming off of it was nasty looking and had tiny hairline fractures. could that be it. the fractures causing a vacuum leak? or would that throw off my idle all the time and not just when the compressor is running

99mustanggt

Sounds like you have a vacuum leak in your climate control hoses and not a problem with the IAC.

Lowtryx

+1

If it were your IAC you would be getting other symptoms (Most likely stalling or other throttle issues).

Of course, there is no harm in checking. Pull it off and be sure that the spring and valve move freely. Spraying tune up cleaner inside can free it if a little light corrosion is to blame or coking. Although, like I said I don't believe it's your IAC. I'd go with vacuum leaks as well.

masterofthepuppets99

well im gonna check my iac in the morning. and then ill look for a vacuum leak. i swear it has something to do with my c&l plenum since it started happening after that swap or pretty much around the same time. ill get back to you guys tomorrow. thanks

Lowtryx

Be sure to check all vacuum lines attributed to the Plenum. There are several lines off of the intake which could very easily cause a substantial leak. Check all lines/hoses before your IAC.

masterofthepuppets99

so i checked for vacuum leaks on and all around any lines that could use vacuum. i used wd-40 and sprayed all over. i found nothing. no idle changes. should i use starting fluid instead? or perhaps i should check my climate control vacuum lines...they are controlled by vacuum right? how would i go about doing that


update: cleaned my iac just for kicks. made no difference

Frostbitten

your idle should be around 700rpm. Mine is at 750

Lowtryx

Not when he has set it to 650 with his tuner.


Use starting fluid and, like you said check for idle changes. If you have a serious enough vacuum leak it should rev up a bit. Spray around any suspected areas.

99mustanggt

Pull out your climate control and see if you can see or hear any leaks behind your dash.I wouldnt spray anything in there because you'll be smelling if for awhile if you do.Try carb cleaner instead of WD or starting fluid.

masterofthepuppets99

thanks alot. i will increase my idle. and ill will try carb cleaner tomorrow( well i guess today lol). ill also pull out my climate controls and take a look around