hanging idle

[ALS97GT]

i have a 97gt and i have the hanging idle problem. i have heard of people doing a IAC restrictor plate, what do you guys think? anybody have them or have done them. i have heard good things, and i have heard its not true that it works. Let me know. Thanks.

 

[joekd]

I have the IAC and EGR restrictor plates on my car (made them myself out of sheet aluminum), also had the same setup on my 00 GT, RPMs dont drop instantly but are worlds better then they did without the plate in place

Best part about making it yourself is you can start with a small drilled hole and work your way up until you are happy. If you dont like it at all just remove it.

 

[ALS97GT]

how hard are they to make and install? what do you think of this one on ebay?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=120487943149&viewitem=&sspagename=STRK%3AMEWAX%3AIT

 

[joekd]

t hoestly is VERY easy to do and I think that price is an absolute joke

You can buy an entire sheet of aluminum for less then that, trace your IAT gasket, cut it out and drill two holes, one same size as the hold in the gasket and like I said experiment with different sizes for the pass side.

If you dont have metal cutting shears another way to make them is using gasket material which you can buy at any parts store, same thing, cut to match IAC gasket then drill holes. To be honest you could even make it using a soda can you cut up.

 

[duff daddy]

My idle was hanging terribly had it tuned still was very bad, I did some work and used the Idle stop screw on the T/B and it became worlds better, but I would just make my own if thats teh route you would like to go

 

[NERD]

Some of the cheaper throttle bodies dont meter the air well enough and can cause the decay rate to change (hanging idle) this problem can be compounded by free flowing exhaust. IDK why joe even bought up the EGR since it's not even remotely the same thing. The EGR restrictor plate is cutting off all exhaust flow. (If you decide to do this mod you'll need to have your cel turned off. It does nothing to affect the performance even with the cel)

If you can't have the decay rate tuned out then I would suggest the iac mod. To make it easy just buy some gasket paper and make the hole about half the size of the standard hole and adjust from there. Make sure every time you test it you clear the rom by unplugging the battery.

The throttle stop screw has nothing really to do with idle.

 

[joekd]

ok, you inspired me to make a how-to for the IAC plate

http://sn95forums.com/index.php/topic,44220.0.html

 

[duff daddy]

The throttle stop screw has nothing really to do with idle.

Thats exactly what i thought, and its the only thing that was changed on the car from the prior tune and it worked. what happend was the idle was adjusted with that screw and not in the tune, so i guess i just had a shit tune. but yea it doesnt make sense like you said, but it worked

 

[ALS97GT]

ok, you inspired me to make a how-to for the IAC plate

http://sn95forums.com/index.php/topic,44220.0.html

thanks this will help... nice picture haha

 

[lordgufi]

throttle screw allows adjustment within the decay rate. mechanical ref + electronic control. i had to do the same thing to get my car to idle.

other wise my car would hunt for an idle , attempt to find it and it couldn't so it would jump back and forth and then die.

pushed the screw out 3 turns and boom idled perfect ( mind you i tried setting idle with tuner between 750-1250 and nothing worked untill i adjusted the screw ) finally got it set at 950 rpm and its solid

 

[joekd]

thanks this will help... nice picture haha

Didn't have one of mine and really didnt feel like pulling it off my car for a pic

 

[Pennywise2]

It very well could be your throttle body.I had a 70mm Mac throttle body that would
stick open and I would get hanging idle.Switched out throttle bodies and the hanging
idle went away.

 

[lordgufi]

if the throttle stop isn't adjusted correcttly it alows the throttle plate to be slighty open... i dont get how you guys think this has nothing to do with idle?

 

[MustangChris]

It very well could be your throttle body.I had a 70mm Mac throttle body that would
stick open and I would get hanging idle.Switched out throttle bodies and the hanging
idle went away.

mac throttle bodys dont seal well... Ford OEM FTW. or accuuufabb.

 

[NERD]

"Cliff"

The screw you have been adjusting is not an idle adjustment screw, it is a throttle stop screw used to set the intial airbleed through the TB, so that the PCM can then control the idle by varying air flow through the Idle Air Control (that's why it's called that).

Here 's the procedure for getting the TB stop screw adjustment back to where it's supposed to be.
http://www.paladinmicro.com/PalMFrame00.htm?wks=tba



The only way to change the idle speed is in the tune, the stop screw being only used to preset the amount of air bleed through the TB when the throttle is closed. It is set so that with the throttle closed the IAC is operating in the lower 15% to 20% of it's range when the PCM is controlling the idle speed to provide some "headroom" when low idle speeds are desired and quite a bit of room to increase idle.

Using it (the stop screw) to attempt to control idle speed is a futile task because the PCM will just increase or reduce flow through the IAC to get back to the programmed idle speeds (there are several programed speeds depending on IAT, ECT, load, etc).

If the stop screw is tightened too much, in an attempt to increase idle speed, then at some point too much air will be bleeding through the TB and the PCM will not be able to control the idle even with the IAC completely closed--this generally results in the idle speed being erratic as heck as the PCM tries its best to maintain control.

If it loosened too much to attempt to reduce the idle, the PCM will increase flow through the IAC to keep the programmed speed. It can do this with reasonable success however the engine is likely to stall when the PCM suddenly stops IAC flow (for deceleration, etc.) and there if far too little air bleed through the TB to keep the engine running. At the extreme the throttle plate will stick closed due to engine vacuum, binding, and stiction...

Disconnecting the battery will clear the KAM (Keep Alive Memory) and force the PCM to relearn the idle air trims needed to maintain the programmed idle speeds, however eventually it will relearn the trims anyway.

 

[GDawg]

Have you tried removing that intake spacer and see if it goes back to normal?