Sorry to steal your thread, but when you say idle like crap would you notice it on the rpm guage? Or would it just feel rough? Im geting codes for my EGR system failing but im wondering if the IAC is failing too

 

Could be the IAC. When the EGR fails it can cause the motor to run a little rich or lean depending on how it fails which can cause it to run rough. When the IAC fails it causes the car to idel irradically and the motor will run rough till the ECU adjust, if it adjust.

 

Ok, so if my rpm guage isnt going crazy then its just my EGR system? Got it lol... well imma test the IAC anyway just to be safe... thanks for the info and sorry again to steal your thread!!

 

Maybe, maybe not, the IAC is a little bastard of a sensor sometimes.

 

You aren't supposed to run additives that often, it clearly says so on most of the bottles. Sounds more like you have a leak that's letting air in, or a fuel pump issue.

 

Oh ok, the one I used said to run every time I change the oil, but I haven't done it since December. And mustangsally yeah the rpm is steady it just feels rough and sputters

 

hmmm maybe this would explain why sometimes when I try to crank it it sounds like a ton of air or a wierd hissing sound but only when its cold... and then when it warms up outside it sometimes takes forever to crank

 

I'm getting the same thing too, I thought it was just my aftermarket CAI I got from AmericanMuscle because it makes a loud hissing sound that's even louder than my exhaust. But now that I think about it, I don't hear it anymore now that it's warmed up, only when it was cold outside.

and Ryan - when you're talking about air leaking in, do you mean the CAI or is there another spot more prominent to leak air? I HAVE had previous problems with the AmericanMuscle CAI leaking in some air because even with the clamps tight it'll seep a bit.

I really hope it's not the fuel pump but I will have the pressure checked just in case.

 

He means air getting into your fuel lines causing bubbles, this is a more unlikely extreme but anything is possible. Usually it would enter near the fuel pump or fuel filter due to a light failure in the seal, on the flip side you would leak gas.

A vacuum leak on the other hand causes a whole new area of issues and they are hard to detect without a smoker (a device that puts out colored smoke and you place it near the air intake and look for the leak spot). In short to cause the problems you're having you'd have to have one hell of a vacuum leak causing enough air to get in behind the MAF throwing off your air/fuel mixture (would run lean) causing issues, however the issues would get worse as you climb in the power band.

I'm still putting my money on the IAC or another failed sensor.

 

I see, when I climb the power band it actually feels better (which is why I've been rolling a ton of stop signs recently because I hate the feeling when I'm idling haha...) Only in idle and start up is when I'm having issues which is why I was quick to agree with you on the IAC. I don't believe it's a vacuum leak. But as far as running lean, that's a possibility. There's little protecting the MAF from getting dirty (americanmuscle cai), so maybe the dirty MAF sensor could be causing this? I just want to make sure I'm ruling out the smaller problems before I start replacing parts.