Re: Hanging/Slow dropping RPM FIX inside.
 

made my own plate this past weekend, the 5/32" hole was way to small for my 01 cobra. poped it off and drilled a slightly larger one and wala worked like a charm. after driving for a bit in neutral approcahing a light the idle will hang at 1200 or so then slowly creeps down to 750-800. excellent mod

Re: Hanging/Slow dropping RPM FIX inside.
 

This is a unique solution to the IAC hanging issue.

Disconnect battery cables (without creating a spark) for several hours, may take 2 or 3 tries. This apparently is the only way to reset the computer.
Also, pump the brake pedal before detaching battery cable. Will eliminate
any residual electricity.

Was reving up to 2500 consistently until I applied the above technique.
Idles like a charm now.

Go figure.

Re: Hanging/Slow dropping RPM FIX inside.
 

When I bought my Mach I got one of NC Mach's IAC restrictors with it not installed. I finally decided to install it today and loved it for the first 10 minutes of driving. I stopped at a red light and the RPMs decided to hang at about 1400 for a couple seconds then dropped down to about 400 and tried to die. So, I pulled into Wal-Mart and removed it real quick and it was fine. I guess I need to drill the hole out a bit. My only mods are JLT RAI, Magnaflow cat-back, SLP catted x-pipe, and PHP 3/8" intake spacer.

Re: Hanging/Slow dropping RPM FIX inside.
 

Enlarge the smaller hole to 11/32" and see how that works. If need be, keep enlarging 1/32" at a time until you find the right size for your car.

Re: Hanging/Slow dropping RPM FIX inside.
 

Did this free mod since I already had some aluminum sheet stock laying in the garage. I got it all cut out and made the small hole 9/32. Drove it around a bit and it was idleing really low. Cut about another 1/32 to make the small hole 5/16 and it works like a charm. What a difference this has caused. During cold starts it will idle up to 1600 then drop instantly to 1100 then just a sec later it is down to 800. During shifting it is an instant let of gas and the idle goes down. No more hanging or raising idle woot woot.

Re: Hanging/Slow dropping RPM FIX inside.
 

Just did the plate also. I did both holes small like the EBAY Mr Gasket one is. Works great! Love it. Thanks for the Free Fix :THUMBSUP:

Re: Hanging/Slow dropping RPM FIX inside.
 

im always jealous of how my friends carb'd 306 fox sounds when he revs up...

so im gonna do this mod tomorrow and take before and after vids..

Re: Hanging/Slow dropping RPM FIX inside.
 

Somebody was selling these plates on ebay a few weeks ago for $10, but they're not there now. Does anyone know who that was, or how I can get one. I know I can make my own, but these were real high quality.

Found the answer to my own question. It is NC Mach 1 and when they're not on ebay, you can order them here: http://webpages.charter.net/fordcoupe/Mach1iac.html

Re: Hanging/Slow dropping RPM FIX inside.
 

Thank you Colloggett

Re: Hanging/Slow dropping RPM FIX inside.
 

Good find.... Thanks!

Re: Hanging/Slow dropping RPM FIX inside.
 

Thanks for posting this.That has always been aggrivating as crap on all these cars.

Re: Hanging/Slow dropping RPM FIX inside.
 

Great mod, it works like a charm. I didn't read through all of the replies but for a cammed motor I would suggest going with a 3/8" hole. Mine had a tough time idling with the a/c on and died on me twice after pushing the clutch in to stop with a 9/32 hole.

Re: Hanging/Slow dropping RPM FIX inside.
 

Just did this at 5/16" hole. Very noticeable difference. Thanks!

Re: Hanging/Slow dropping RPM FIX inside.
 

I'm currently having an issue where the RPM will hang at about 1100-1220 when I come to stop for a few seconds then will drop to the proper 875RPM, will this fix that issue?

Re: Hanging/Slow dropping RPM FIX inside.
 

Nope.

Re: Hanging/Slow dropping RPM FIX inside.
 

Hello. Is the problem of hanging rpm only for the manual Machs?
My auto Mach doesnt have this problem.

Thanks.....

Re: Hanging/Slow dropping RPM FIX inside.
 

yes.

Re: Hanging/Slow dropping RPM FIX inside.
 

Any idle issue present can be remedied with the IAC tables in the tune.

Not trying to step on any toes.

Re: Hanging/Slow dropping RPM FIX inside.
 

Does a accufab TB will work well with the IAC plate from NC MACH1

Re: Hanging/Slow dropping RPM FIX inside.
 

I installed the restrictor plate that I bought from NC Mach 1 (good quality part). Initially I saw zero change until I re-loaded my tune. It did not completely fix the problem but at least is it not shooting up to 2k-2.5K at the light. I am still seeing about 1.3K-1.5K even after lowering my idle with my tuner, but not all the time.

Re: Hanging/Slow dropping RPM FIX inside.
 

What throttle body do you have? I had to adjust the blades on the Acufab along with adjusting the TPS to get the voltage right. I also noticed the idle hangs for awhile after loading a tune.

Re: Hanging/Slow dropping RPM FIX inside.
 

I tested my voltage last night and it was at 0.94, slightly lower than it should be. I havent had the chance to adjust it yet but plan to get to it later today. I just bought the car about a week ago and I am still trying to figure out what all has been modified. The high idle when I engage the clutch is aggravating...

Re: Hanging/Slow dropping RPM FIX inside.
 

I adjusted my TPS to the correct voltage. I guess I am going to try replacing the IAC valve and see if this helps. :frown:

Re: Hanging/Slow dropping RPM FIX inside.
 

i have same problem ever figure it out or find a fix

Re: Hanging/Slow dropping RPM FIX inside.
 

Just got my 04 a week and a half ago. Perfect in every way except for the high idle problem. Joined up here and read every thing posted regarding this problem. Car came with a K&N CAI, flowmaster exhaust, 18" wheels, and I'm not sure about anything else. (tune, etc.) So here is what I tried:

New IAC valve.....no change
New TPS sensor.....no change
Clean everything (throttle body, pcv, mass airflow sensor, air filter) and check for vacuum leaks.....no change
Make that silly IAC restrictor out of metal from a discarded acetone can.....problem solved! :orange:

Go figure.........I just had to tell somebody.

Although the post is almost 8 years old, thank you mach1canuck