4.6L (1996-2004 Modular) MustangTechnical discussions on 1996-2004 4.6 Liter Modular Motors (2V and 4V) within. Sponsored by Cruizin Concepts
Welcome to Mustang Forums!
Welcome to Mustang Forums.
You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!
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
This ad is not displayed to registered or logged-in members. Register your free account today and become a member on Mustang Forums!
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.
Red 1996 GT
BBK Shorty Headers
Pypes HFC'd X Pipe
Hurst Billet Aluminum Shifter
Rear Window Louver
Drilled/Slotted Rotors with High Perf. Pads
Sequential Tail Lights
Awful Looking Stock Rims Painted Gun-Metal
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
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
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.
CMS stage 2's,comp springs,and Bullitt intake waiting for install.
Looking for focus fuel pump and ported heads.PM me if you have any.
This forum is owned and operated by Internet Brands, Inc., a Delaware
corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford
Motor Company or its related companies in any way. Ford® is a registered trademark of the Ford Motor