Hanging Idle

I would start by making sure the IAC is adjusted correctly. Turn the screw under the cap down until it bottoms out, then back it off a turn. If that isn't the problem, then move on to other tests. Have you pulled codes?

Dave

nmcgrawj said:

Im not sure on the hanging idle, hopefully more will come in and help out with that.

But i do know with our computers, everytime you start the car up it re-calibrates itself with the current TPS setting. SO with that, you cant change it, cause the computer will keep changing to adapt to it. Im pretty sure this is the way it works. Foxes can be adjusted because the computer will not adapt and whatever you manually set the TPS to, thats what it will be.

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Foxes computers also adapt. My car was pulsing a little bit, so I decided to clean the IAC. Turns out, now my car will idle at 1500 at startup (after sitting overnight or such) and after about 30 seconds it will drop to about 750. I thought the IAC was bad, so I replaced it and nothing changed. Now my car will rev and come back to idle fine. But when I make it sit at 2k, whether driving or not, it will take forever for my car to come back to idle.
Damn thing. I'm going to look at what HairyCanary said and hopefully it fixes it.

Hanging Idle possible solution

I have a buddy that has a 94 vert gt, he has a cam i am unsure of the grind or specs right this second........a set of pro topline heads, and an edelbrock performer rpm intake.


since he installed all this i tried all the usual tricks to get it to idle including


fuel pressure
timing all *'s
rasing idle manually
slotting the tps (which helped mine)
cleaning maf, and everything associated.
changing filters


yata yata yata........

Well this evening we remedied his car i believe. We installed a 93 model IAC sensor, valve whatever it is called technically.

IT DID THE TRICK......... car fired right up and idled smooth......but around 1000 rpm.........so we had to adjust it..... and then we eventually got the idle down to around 850 and it lopes like a mother without stalling.

I was trying this as a last resort, was tipped off on this by another stanger on another board. I WILL be doing this to my car when it fires up again.


just thought i would share...........................................


jason

Try this link.....do all 5 steps if you feel its needed or time to just check it....i did steps 4&5...cured my hanging idle, as i was driving around with the IAC unhooked...
driving WITH the IAC unhooked will work....until you put a load on the motor, like turning on the AC while idling or the heater on...with a load, it will stall instantly....
i run a Fox TB set-up....this link cured mine...yes, i opened the TPS holes to re-set it...once ONE THING is moved...you gotta re-set it all...
mine would hang bigtime at morning idle and between shifts...
some say the SN95 TPS is non-adjustable??? others will and have reamed the TPS holes to re-set the voltage...
I may be wrong in my thinking but, if at idle the TPS see's over 1.0 volt,(mine was at 1.2) its gonna think your into the throttle?? hence the idle hanging...mine would always hang until i did the adjustment sequence per the link....
I went thru (3) IAC valves thinking they were the culprit...no dice...they all worked fine...i just needed to re-set the idle sequence...any of the 3 IAC works fine now....if you tweaked the throttle screw....you should really re-set it properly per the link...

http://www.muscularmustangs.com/maintain.html Follow the steps and see if it helps.????

oooops

RIO5.0 said:

I may be wrong in my thinking but, if at idle the TPS see's over 1.0 volt,(mine was at 1.2) its gonna think your into the throttle??

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The 94+ EEC does not recognize 1.0V of TPS as anything special.

HairyCanary said:

The 94+ EEC does not recognize 1.0V of TPS as anything special.

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Thats what i thought, does it just ignore the TPS or does it reset everytime you start up?

Change the air intake temperature sensor

My idle has been hanging at 1500 lately. After reading thie thread I tried unplugging my IAC valve. The car fired up and idle was good, between 700-900. I was able to drive it without any problems and idle always returned to where it should be. I guess thats a sign to chenge the IAC out