YUNOIDLERIGHT

Hello all,

I have been reading these boards for little over a year. Seems google always directs me here.

As you guys have guessed... I have the idle surge issue when shifting. First noticed when I replaced my IAC when it went bad. didn't deal with it until i delt with other problems first. Now... its that time. For the past several months I have been checking for leaks, bad hoses, and every thing posted that I should check. I have taken it to 5 shops all recommended. No one could figure it out. I am on the verge of constructing a plate for the IAC. But before I do, is there anything else I should check?

I have:

Checked hoses, seals, gaskets, no vacuum leaks.
It idles smooth
Has plenty of power
New plugs, wires, oil, IAC, Diz, ICM, Coil
Run Chevron 91 (CA)
Sea Foamed few weeks ago, not much smoke (Clean engine?)
Adjusted air bypass screw
Idles at 650~
Reset Base idle yesterday (May need to do it again after adjusting the screw the little one under the plastic cap by the IAC)
Cried several times, begged, pleaded, beat with stick


Once the RPMs do drop its pretty quick no floating hanging.

Other notes:
After cleaning TB (Jesus him self would eat out of the TB its so clean). I can hear a high pitched hiss/whistle coming from under the hood under hard acceleration. Friend says its just the CAI doing its thing, but I have NEVER heard that sound till I cleaned the TB. Could it be the TB gasket that connects to the Intake? Does not show signs of leaking but hey who the heck knows right? Also, how clean does the IAC inlet have to be? I cleaned it as good as I could, but there *MAY* be a little tiny tiny tiny tiny bit of carbon left.

Also, could it just be a faulty IAC?

Other things I have noticed:

When it surges and RPMs are under 3k, they shoot up to between 2.5k 3k. When over 3k drops slowly, to 3k hangs then drops almost normally. Please help me. If I don't figure this out, I am going to go insane.

Canary94GT

Try cleaning the MAF sensor and running the self test if you haven't.

I know when I've disconnected the MAF sensor, it caused a surging idle.

Next I would get a Haynes/Chilton manual which outlines how to check the voltages to your iac, tps (another possible culprit of surging), and maf sensor to make sure everything is correct.

Oh and about the high pitched hiss/whistle - that could be a vacuum leak of some sort. Get some extra rubber hose if you have some and hold it to your ear then move it around the throttle body/cai/etc and see if you can find the source of it.

mattdel

Don't forget about the ECM strategy that bumps idle speed while shifting to prevent a stall. Could be malfunctioning.

YUNOIDLERIGHT

I have cleaned the MAF like last week. IAC is new. But it is from Autozone... I am going to check TPS today when my friend deciedes to show up to work.

4rdnut

I have a hanging idle for three years now. The computer is actually programmed to hang the idle and the vss sensor also bumps the idle up so when you brake the engine won't stall. My rpm hang is between 1200 and 1500 rpm and returns to 850 rpm after three seconds. I have an automatic so its not as bothersome. The whistling your getting is from the autozone iac valve. The air holes are cut very sharp, you can file or chamfer the holes smoother to lessen or eliminate the whistling. Now you know why people convert to carburetors. If you can find another computer for cheap try that or have your computer reprogrammed in the dashpot decay circuit which controlls that hanging idle bull sheet.

AdderMk2

you guys kill me with this "adjustment" crap.

stop ****ing with things you know nothing about. 99% of the time, the high idle and hanging idle issues that SN-95's have are directly related to VAC problems, and people ****ing with the god damn throttle stop screw. IT IS NOT AN IDLE ADJUSTMENT POINT!!!!!


Perform a PROPER base idle reset, fix your vac leaks and stop screwing with ****.

YUNOIDLERIGHT

Well for one Mr. AdderMk2 guy, your statements are not needed here. So feel free to gtfo of my thread if you don't have any advice other then being a complete freakin jerk. Do you roger that guy? I have seen you on other forums and do not appreciate how "direct" you are sometimes. Your advice is indeed useful and great, but the delivery and the unneeded rudeness you tend to put into your advice is something I do not need. So please feel free to refrain from posting in any threads of mine if you continue to be rude. Thank you my good sir. And also sir, it was not the throttle stop screw, as that is just a bolt (Shaft?) that looks like Ford did not want me to move, I actually adjusted the little screw underneath the plastic cap just to the left of the IAC. FYI home slice, get your facts straight before you accuse me of messing with **** on MY car. And you know what? Last time I checked, I lived in AMERICA where if I wanted to mess with that bolt I could, because holy ****, I can. That is all sir.

I know the idle is supposed to hang for a little bit, but 4 seconds seems somewhat long. My self, and several other persons thought so also.

I think I have figured it out, according to my haynes manual, to adjust the IAC I have to mess with that screw, as I did, then I reset the base idle, and now the hang is no longer there. There is still a rise in RPM's but no hang. The rise could be contributed to a VAC leak that I, nor anyone else can find.

I found it odd that this issue started when the IAC was changed. Not before. So my thoughts where along the lines of an IAC issue since I did not have a vacuum leak before I changed it, then some how magic happened and a vacuum leak formed the same MINUTE i changed the IAC? Possibility yes, likely? Eh.

So how I fixed my hang? Screw the idle air screw all the way down (as I did) then back out 1/4 - 1/2 turn at a time, clear the computer each time you adjust your screw (To be safe yeah takes awhile... but atleast you KNOW the computer memory is fresh) and adjust accordingly.