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Fox T-Bird/Cougar Forums

Technical => Engine Tech => Topic started by: seanef26 on February 03, 2005, 03:32:21 PM

Title: IAC/Stalling Problem
Post by: seanef26 on February 03, 2005, 03:32:21 PM
I'm having rough idle problems.  I saw a message that said a quick way to check your IAC is to have the car idling and disconnect the wire harness.  They said that the RPMs should drop down to about 400-500.  When I did this in my car, the idle dropped down for a few seconds, fluctuated a couple times and stalled.  Does this mean I have and IAC problem or an incorrect idle setting?  I was under the impression that my idle was not adjustable ('86 5.0 SEFI).  Any ideas?
Title: Re: IAC/Stalling Problem
Post by: Tbird232ci on February 03, 2005, 06:22:53 PM
http://www.foxtbirdcougarforums.com/showthread.php?t=1455

read my reply towards the bottom of the page, thats how adjust the idle and TPS
Title: Re: IAC/Stalling Problem
Post by: CougarSE on February 04, 2005, 03:25:27 AM
If you do what T-bird232ci said you should be fine.  Over time though tps sensor's will get dead spots in them or just burn out completely.  Working at autozone I have learned that 90% of tps's burn out at the lower rpm settings. like idle and normal driving.  Most of the cars would run fine if you floored it or gave it 75% throttle.  I don't know if the 5.0 has an adjusting screw?  One of you lucky guys key in here and let us know.
Title: Re: IAC/Stalling Problem
Post by: Sly1990 on February 04, 2005, 08:31:31 AM
Quote
They said that the RPMs should drop down to about 400-500. When I did this in my car, the idle dropped down for a few seconds, fluctuated a couple times and stalled.

Your IAC is OK.... Checkthe TPS... as they mentionned...

btw, There is no way to ajust the TPS on mine...
You bolt and it takes place....

When replacing TPS, Disconnect the your battery for 5 min and replug. Your EEC will learn and adjust his new settings.
Title: Re: IAC/Stalling Problem
Post by: seanef26 on February 04, 2005, 11:01:17 AM
I was having high idle and surging problems a couple months ago and I had the TPS replaced.  So I don't think that's it.
Title: Re: IAC/Stalling Problem
Post by: Tbird232ci on February 04, 2005, 02:22:54 PM
Quote from: Sly1990
btw, There is no way to ajust the TPS on mine...
You bolt and it takes place....

thats why i mentions slotting the holes where it mounts

when i bolted mine up, it was at 1.24 volts, which is way off from where it needs to be, they are usually around .89-.91 from the factory, so i had to slot the holes for the TPS so i could adjust it
Title: Re: IAC/Stalling Problem
Post by: zpyro on February 04, 2005, 02:33:19 PM
Quote from: Tbird232ci
thats why i mentions slotting the holes where it mounts

when i bolted mine up, it was at 1.24 volts, which is way off from where it needs to be, they are usually around .89-.91 from the factory, so i had to slot the holes for the TPS so i could adjust it


yeah that's the way to adjust the TPS without messing with the idle screw and making your car idle higher or lower than it's supposed to
Title: Re: IAC/Stalling Problem
Post by: CougarSE on February 04, 2005, 09:36:28 PM
When I first got the cougar home it idled somewere around 1500-1700 so I had to adjust it down.  But my sefi 3.8 has a screw....
Title: Re: IAC/Stalling Problem
Post by: Tbird232ci on February 04, 2005, 10:19:05 PM
all of the cars have an idle adjustment screw, but you need to adjust the TPS so that the computer can recognize that its at proper idle, and when its at WOT
Title: Re: IAC/Stalling Problem
Post by: zpyro on February 05, 2005, 03:33:35 AM
the idle adjustment screw adjusts the throttle plate, which in turn adjusts the TPS. if your idle is high and you lower it with the screw, you also lower the TPS voltage. by slotting the TPS and loosening the screws you can adjust it independent of the throttle plate
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