i heard something about an IAC mod that makes ur car rev down quicker or something like that by sticking something inbetween it..i dunno...anyone hear of this?!

 

https://mustangforums.com/m_2625353/tm.htm

 

yes, use that link above. i did it and man what a difference. the hanging rpms are almost eliminated, and it will sound a little different too.

 

I took mine off...gas mileage went to hell, and my car was choking and my T/B was FULL of black sludge. NEVER AGAIN!!! [:@][:@][:@]

 

[/align][/align]Something else must have been different--the IAC has little to nothing to do with overall fuel economy and only comes in to play at idle and closed throttle.I've had a 0.300" restrictor plug in the IAC hose on my '03 GT for over 12k miles and regularly get 22.5 to 24 mpg with 3.73 gears--the only noticable changehas beena much faster drop in RPMs between shifts (accompanied by a very nice burble in the exhaust)...[/align]

 

ok besides the one guy who claimed it to be a problem anyone else that has done this have an issue?

 

CliffyK the reason why gas mileage goes down is because of this:

When the IAC is restricted by a plug/smaller gasket, the cars computer does not reset the amount of fuel that is injected into the motor to keep the constant air/fuel ratio. With a stock gasket, the correct amount of air is administered when dropping back to idle, and during idle. The car is essential running very rich with this mod. There is limited airflow at idle and not all the fuel in the cylinders is being burned---thus giving that "pop-gurgle" sound when dropping RPMs. I've heard this theory before, but I didn't think it was a problem until I started to get the typical backfiring sludge in the intake and t/b, and the horrible mpg's.

Hope that makes things clear. If you have a flash tuner, then you don't need to worry about anything I just said. Just reset the air/fuel ratio to match eachother with the limited airflow of the new IAC gasket.

 

[/align][/align]This is a very confusedinterpretation of what the IAC does--as it basicallydoes nothing that either cracking the throttle plate (like to oldsolenoididel controls) or dampening it's closing (like a vacuum dashpot) wouldn't do. The computer responds to the added airflow (measure by the MAF) and then injects more fuel--adding a restrictor in the IAC line just slows things down a bit. [/align][/align]Here's what the shop manual says about the IAC:[/align][/align][/ul]
Restricting the air flow into the IAC merely slows it's response, because the PCM doesn't know that we've restricted the flow. If you restrict it enough the engine will not idle correctly, and the electronic dashpot function will not keep the engine from stalling when you chop the throttle--however it cannot affect overall fuel economy and a/f ratio.

I am not saying that you didn't experience these things,however it wasn't an IAC restrictor (even if you plugged it up solid) that caused it...[/align]

 

Sounds like you definately know what you're talking about! That was just what I heard from a few other guys on Cobra forums.

I don't know about our engines, but is the MAF sensor (the wire that gets heated and cooled) located before or after the IAC inlet? Jus wondering.

 

The MAF sensor is before the IAC inlet line, that's why the air allowed in by the IAC isreferred to as "metered" air--metered air whether drawn into the plenum through the TB or the IAC will cause the engine speed to increase as the computer adds fuel to match the additional air.[/align][/align]Cobra's may react differently to this mod, I am not as familiar with their engine control systems...[/align]