[40YRMustang]

How's it going guys?

I searched the forums, trying to look for similar problems, but couldn't exactly find a correct answer.

I'll try and explain to you what all is happening, and what all has been put into my car.

It's a 40th Anniversary Mustang GT, the ONLY, and I mean only mod that has been done to it is the Cold Air Intake.


Now. When I start my car, it's be fine. It idles at about...750 RPM, normally. Then about every 10 seconds, my car will sound like it is BEGINNING to die, but not quite - and the needle will bounce maybe to 600 RPM - 650, then returns back to the normal 750 RPM.

I've cleaned the IAC, which wasn't dirty at all - the throttle body was relatively clean, had a slight film over the backside of the flap, but that's it. I took off the cuppler around my MAF, and sprayed some cleaner into it.

My MPG is absolutely terrible. I think it's hitting roughly around 12-13 MPG at the moment, and once again - I have basically no mods to it. Can someone help me out here? My guess would be that it is the O2 Sensors, which are plugged in.

No, it's not my AC - I have an AC delete on it right now, as my compressor went bad earlier this season. Thanks guys!

Edit: It JUST hit 47,000 miles on the car. Never been in a wreck before, with 2 previous owners. Although - when I first bought the car, it had brand new cats on it. How did I know? The damn factory sticker was still on it, of course it melted on. :| lol

[03Black2v]

I'm having the same problems basically, except it only sounds like its going to die very rarely and my mpg is worse. Might be clogged cats. Quick MAF test:
1) Turn your car on
2) Notice how it sounds at idle, if its rough, smooth etc..
3) Unplug your MAF and see if the idle changes. If it dies, I believe its fine, if it comes back to the same idle then its bad. When you unplug it, it will idle really low then come back up to normal idle if its bad.

[laser46]

Any DTCs set? Also, check for leaks in your CAI tubing.

And just an FYI: All 04 Mustang GTs and V6s have the 40th emblem on them. There is no special edition, unlike the 99 35th GTs which did have a special edition. Pretty much like the 09 GT/V6. They also all had a 45th fender emblem but no special edition.

[02NightRider]

That MPG is really bad. I just filled up today and got 22 MPG. Check your cat's and see if they are clogged. Or just get an O/R X

[03Black2v]

Is there any way to check yourself if the cats are clogged?

[01TB03AB]

MIGHT be th IAC. (idle air control) valve. One of the vacumme lines plugs into it and it sends air into the intake manafold. key is, inside it has a spring that may rust or wear out. The first pic is the IAC disconnected from the horse throttle body area. second pic is the inside where you can see the spring. mine went out and the rpms would stick and i would hear a humming sound and the engine would die. not sure if this is your prob, but i never heard of it until my bro mentioned it and it does mess with the idle.

[40YRMustang]

I don't believe it's the IAC, it is as clean as it could be. Unless something internally is wrong with it, of course.

I'm not sure, never checked on the DTC's - but I don't have any CELs if that helps, never had one with this car.

But I probably should also give a note, that while driving - it will stall out. The other day, I was going ~40 in a 35, and it simply stalled. I wasn't doing anything fancy, no jump on the start - just driving normal. It started right back up, of course.

I suppose I could check it again, 01TB03AB, but I've already cleaned it about 4 days ago. Going to test out the MAF real quick.

For general reference - on my CAI, I don't have a...can't think of the word for it, but the metal tightening ring around the MAF piping, on the upper part of the coupler. Could that cause anything? And the part of my CAI where you have 4 bolts that are supposed to be attached to the next pipe, I have about a... 1/16 gap of nothing sitting there, as there is no spacer. Could that hurt it?

[JustRight]

Sounds like a leak (very common) in your CAI piping. Pull the assembly off and take it to a dark room, then shine a light inside of it. If you see light anywhere around the outside, there will be at least one problem.

[40YRMustang]

I do know that I have gaps in between my CAI.

But as an update to the MAF, I just unplugged the wire to the MAF, started my car up - revved it a little. No CEL came on, but the idle stayed exactly at 750 as it should. Didn't bounce at all. So, should I clean it? And if that does nothing - buy a new MAF?

By the way, does anybody know what the tool is called to get the MAF housing off? It looks like a star bit, but it has a nipple in the middle of it. :| Thanks!

And I'll try to clean up my CAI piping, it whines when I hit it past 3K RPM. Probably not good. :p

Oh, and if I have to end up replacing the MAF - which one should I choose if the following is the CAI I have:

http://www.americanmuscle.com/mugtv8pocoai.html

[stal94gt]

if you have gaps in your cold air your letting un-metered air in which causes a lean condition. since your car idles better with your maf unplugged leads more to a intake leak. if your maf were bad you would pop a code for it. also the star bit with the nipple requires a tamper resistent tool, just a standard torques bit with a hole drilled in the middle. you can get them at autozone. if you plan on replacing your maf replace it with a oem one cause any other maf will require a tune.

[laser46]

Originally Posted by 40YRMustang For general reference - on my CAI, I don't have a...can't think of the word for it, but the metal tightening ring around the MAF piping, on the upper part of the coupler. Could that cause anything? And the part of my CAI where you have 4 bolts that are supposed to be attached to the next pipe, I have about a... 1/16 gap of nothing sitting there, as there is no spacer. Could that hurt it?

You just found your problem. Just put the stock setup back on, as CAIs aren't worth much on 2V cars.

[40YRMustang]

Yup, I'm trying to put it back to stock. Does ANYBODY know what size the damn bolts are for the MAF housing to connect to the 4 bolt entries? I thought I had the stock bolts on, apparently not. -.-