Cure for hanging revs while shifting/stopping!!!

[2011GT]

You should see the following, the IAC assembly has two "ports" with the solenoid controlling the air flow between these two ports, what we want to accomplish is to restrict the airflow leading through this.

To do this, there should be a small gasket on your intake, or it could be stuck to the IAC valve.

Remove this (carefully)

Trace out the shape of this gasket as well as the holes for mounting bolts, and the two air holes, onto a piece of 1/32" aluminum or something similar.

Cut out the outline of this "restrictor plate" from the aluminum.

Cut out the holes for your bolts to go through.

Cut out a single one of the Air holes.
Now the tricky part. You have to decide how big to make the other hole because this determines the amount of air you are restricting.

The smallest you should go would be around 5/32", the worst case if you go to small is your car will stall when fix is complete, if this happens just take the plate out, make the hole bigger, and check that.
The hole I used is around 9/32" which is about the medium you would want to go.

After your "restrictor plate" is cut out, mount it with the small hole on the passenger side of the IAC, and make sure to replace the gasket against the intake.
Start your car, you should notice the RPMs drop when you start back to normal very quickly.
If it idles smoothly, try putting turning on the AC, this will load the engine down.
If your car stalls out, remove the plate, make the hole bigger, try again.
If still idling smoothly take it for a spin. You might need to adjust your driving/clutching style after being used to the crappy RPM hang, so don't be discouraged.
Also, you might want to disconnect your battery during the procedure to make your computer relearn tweaks after you finish.

If, after you start the car you notice a "whistling" sound, then take a look at your plate, make sure the BIG hole is at least as big as the hole on the IAC valve. Also make sure edges of holes are rounded (sharp edges are bad), and the holes are round. This happened on mine, and I fixed it.


Thanks,
Herbstang from mustangevolution.com

 

[Teddyzee]

Yes, that's a cool mod.

On my 4.6 Mustang, I made a completely solid gasket, blocked it off entirely.
You then just set the idle with the screw. (no head on the screw on '94+, not sure about the Ranger throttle bodies. Vice grips work, though)

The car now idles exactly where I want it, the moment I take my foot off the gas. No more 1500rpm idle. (mine idles at about 550. An automatic or if using AC, you may want it slightly higher)

Many guys go nuts when they hear about this. "You need a tune to correct or modify the idle". Um, no.

 

[2011GT]

Yes, that's a cool mod.

On my 4.6 Mustang, I made a completely solid gasket, blocked it off entirely.
You then just set the idle with the screw. (no head on the screw on '94+, not sure about the Ranger throttle bodies. Vice grips work, though)

The car now idles exactly where I want it, the moment I take my foot off the gas. No more 1500rpm idle. (mine idles at about 550. An automatic or if using AC, you may want it slightly higher)

Many guys go nuts when they hear about this. "You need a tune to correct or modify the idle". Um, no.

My 98 ranger has a screw you can turn to change the idle. It's actually called a butterfly stop screw. Does your check engine light come on with your mod?