[zinc02GT]

Would a dirty IAC cause the rpms to hang a little between shifting and when coming to a stop?

When IM coming to a stop, its becoming more and more often that the rpms hang at 1000 then drop to 800 when I finally come to a complete stop.

Is the IAC the culprit?

[White99stang]

yep, ford iac, the biggest piece of shit they ever made.

[zinc02GT]

Originally Posted by White99stang yep, ford iac, the biggest piece of shit they ever made.

I dunno what happened, it posted twice...

sorry you can delte this one white

[zinc02GT]

Originally Posted by White99stang yep, ford iac, the biggest piece of shit they ever made.

I think their headunits are a close second...

So what can I do? how exactly do I clean the bugger?

[White99stang]

i have never cleaned them, i just have replaced it on my car 4 times already. But if you do a search i know for a fact its posted on how to take it apart and clean it

[zinc02GT]

Originally Posted by White99stang i have never cleaned them, i just have replaced it on my car 4 times already. But if you do a search i know for a fact its posted on how to take it apart and clean it

thanks for the help dude. could you delete that one post above for meh? sorry bout that

[03BMstang]

also another thing you can do would be to make a new gasket for the IAC that is thicker, did it to mine and its much better now

[B0B]

i made an IAC restrictor plate and it took care of the hanging idle. makes it funner to drive and can actually increase your mileage a little bit too.. idle is louder though

[M0T0PSYC0]

Originally Posted by B0B i made an IAC restrictor plate and it took care of the hanging idle. makes it funner to drive and can actually increase your mileage a little bit too.. idle is louder though

How ya go about doing that? and what do ya mean by restrictor palte, block some thing off for it or something? I havent looked at mine yet, but have that idle problem,and when I bout my 99 a few weeks ago it already had a new iac installed, so looking for any ideas I can here, any detailed info would be great

[B0B]

i made my restrictor plate using a piece of aluminum, but you can buy them off ebay here. what it does is makes the hole much smaller so not as much air can pass through. it makes rpms drop way faster and also makes the car gurgle a little bit when you let off the gas. the reason the IAC doesn't shut when you let your foot off the gas is for emissions reasons. ford designed it to stay open, letting more air in to burn up the excess fuel when decelerating. they are easy to make, just use your gasket as a template and cut out a piece of metal. i used a 9/32 drill bit for the hole on mine

[M0T0PSYC0]

cool, thanx for the info, Im gunna have to try that then, I am sick of keeping aroun 1k rpm till I completely stop, now I just have to figure why it wants to die then shoot upto 3k rpm after I stop (new iac). But at least I am getting off to a decenet start here, you guys at these boards really have good advice and knowlege. I'd know a bit more but this is my first 5 speed gt, so before when id look stuff up most 5 speed posts in boards never really apllied to me, been more of an auto guy

[M0T0PSYC0]

ok another question on the restrictor plate. wich hole gets normal size and wich small. Comparing as one hole shows the valving and other just shows the aluminum casing. small hole for the aluminum casing hole and valving hole normal size? or other way around?

[hardhitter]

When you decelerate the rpms are supposed to hang up to 1500rpm to allow accessories like power steering to work.

[cliffyk]

Yup,

The PCM, using the IAC, keeps the idle high until you actually stop to make sure the power brakes have sufficient stopping power. An IAC restrictor won't change this much, unless you make the hole so small the idle as a whole is affected.

I played with gasket's and playes but it was a PITA to test different size holes, so I made a plug for the IAC inlet hose. 0.290" (19/64" drill) or so seems to work best.



People have use a 1/2" copper pipe cap as well...

[zinc02GT]

so the rpms hanging for a little bit is biggie then?

[hardhitter]

Originally Posted by zinc02GT so the rpms hanging for a little bit is biggie then?

thats how it should be when you decelerate

[cliffyk]

It's normal for our cars, however it's also one of the first things I modified because it irritated the crap out of me. With the 0.290" orifice I now have the reves drop smartly while shifting and there's a bit of a "pop and burble" almost like a carbureted engine would do...

[zinc02GT]

mine still does that pop and gurgle when I leave it in gear and the engine slows it self down. i love that sound.

I was talking about the entire rpms hanging at 1000 rpm then droping when you completely stop.

[cliffyk]

Originally Posted by zinc02GT mine still does that pop and gurgle when I leave it in gear and the engine slows it self down. i love that sound. I was talking about the entire rpms hanging at 1000 rpm then droping when you completely stop.

That is, as I said earlier, an artifact of the hydroboost braking system which uses hydraulic fluid pressure from the power steering system to provide power-assisted braking. The engine speed is deliberately held high while the vehicle is moving to ensure adequate braking capacity.