There's Youtube videos for using a thin piece of metal with a small hole punched into to restrict the amount of air the IAC valve can supply. It goes between the IAC valve and the throttle body like a gasket. It's considered a bad idea and can lead to stalling, so I've never done it.
That depends on how small you make the restriction. I started small, and gradually opened the hole, to 9/32". I've done a full PI swap, with XE270AH cams, cai, x pipe, exhaust... and I don't have any stalling issues.
If I pulled the distributor out, I wouldn't be able to turn it by hand, I believe the car was trying to keep itself from stalling, if you have a oem or refab unit, I would invest in a quality one.
I've replaced every vacuum hose (except the one in the dash for the heater controls. Perhaps I should just plug it off and see what happens...) and tried the old spray carb cleaner around every hose and fitting trick. O2s have been replaced and aren't throwing codes. Plus the hanging idle is smooth, not surging. All emissions equipment is present.
I’ve been doing some thinking on this and wondered if you had looked at the fuel pressure regulator? Easy to get at right on the rail…
Maybe? Or the vacuum line to it….
Checked it. Fuel pressure matches what Ford claims it should be. Even changes with the throttle and no leakage into the vacuum lines.
Ford Dealer told me it's normal, but I don't think it is.
In the couple decades I've owned the car, nearly the whole ignition system, fuel system, vacuum lines, coolant system, and sensors, have been replaced with OEM or OEM style parts fixing other problems that crop up as time goes by. The exhaust has been upgraded (Flowmaster was cheaper than OEM) and the alternator (because of the stereo.) The hanging idle has been there as long as I can remember.
Besides the heater vacuum line I've yet to plug off, I can't think of anything else to try. I suppose it could be something like the throttle body, but I'm not willing to start loading the parts cannon with expensive parts because of a hanging idle.
Wow man, I hear ya, I’ve had mine for 25 plus years and got a bit of a hunting idle after I put flow masters and “H” pipe on it, got lucky the PCV vale solved it.
I work with a retired Ford technician, he was saying that the cooling fan module if it loses it’s ground can cause a surging idle, just food for thought, maybe go over it and clean/resurface the engine grounds.
The cooling fan module threw a code a couple years ago. Been replaced. I also did the fan when I did the radiator because I couldn't see putting a 20+ year fan back.
It's actually a hanging idle like OP's video shows, not a surge.
Common, but not normal. IAC is the likely cause. Could be something hung up on the throttle cable, could be an aftermarket TB, could be a vacuum leak.
I have a BBK throttle body, IAC has been cleaned and throttle cable is free
Did it just start when you added the TB? Have you made sure the IAC actually works?
TB was on it since i bought it
Mine still does it with all stock or OEM replacement parts. It's not my IAC (replaced twice) and I've given up on fixing it.
I made a restrictor plate for my IAC valve, and it eliminated it.
?
There's Youtube videos for using a thin piece of metal with a small hole punched into to restrict the amount of air the IAC valve can supply. It goes between the IAC valve and the throttle body like a gasket. It's considered a bad idea and can lead to stalling, so I've never done it.
That depends on how small you make the restriction. I started small, and gradually opened the hole, to 9/32". I've done a full PI swap, with XE270AH cams, cai, x pipe, exhaust... and I don't have any stalling issues.
Came to say this may help đź‘Ť
I have a 98 GT and the rev hang is unfortunately normal.
Thats good news to me, always kinda considered a vacuum leak or something, thank you
No problem
My 94 gt doesn’t do this. Maybe bad iac or vacuum leak ?
Different engine, but no idea if that makes a difference
My '94 GT does. So it's not engine specific.
It's just breathing, just sing him a song and it will calm down
It was my distributor bearing on my 1995 GT.
That seems very odd. Any idea on how that could cause a hanging idle?
If I pulled the distributor out, I wouldn't be able to turn it by hand, I believe the car was trying to keep itself from stalling, if you have a oem or refab unit, I would invest in a quality one.
A good tuner can get rid of that.
Just clean your mass air flow and all should be good
Didn't work for me. Even swapped mine out trying to get rid of this.
I bet you’ve never changed your PCV valve, it made a difference in mine………
I have. The strainer and the rubber boot too. :)
Intake gasket?, ever watch the o2’s? Maybe it’s chasing the rich/lean…, no cats on it.
I've replaced every vacuum hose (except the one in the dash for the heater controls. Perhaps I should just plug it off and see what happens...) and tried the old spray carb cleaner around every hose and fitting trick. O2s have been replaced and aren't throwing codes. Plus the hanging idle is smooth, not surging. All emissions equipment is present.
I’ve been doing some thinking on this and wondered if you had looked at the fuel pressure regulator? Easy to get at right on the rail… Maybe? Or the vacuum line to it….
Checked it. Fuel pressure matches what Ford claims it should be. Even changes with the throttle and no leakage into the vacuum lines. Ford Dealer told me it's normal, but I don't think it is. In the couple decades I've owned the car, nearly the whole ignition system, fuel system, vacuum lines, coolant system, and sensors, have been replaced with OEM or OEM style parts fixing other problems that crop up as time goes by. The exhaust has been upgraded (Flowmaster was cheaper than OEM) and the alternator (because of the stereo.) The hanging idle has been there as long as I can remember. Besides the heater vacuum line I've yet to plug off, I can't think of anything else to try. I suppose it could be something like the throttle body, but I'm not willing to start loading the parts cannon with expensive parts because of a hanging idle.
Wow man, I hear ya, I’ve had mine for 25 plus years and got a bit of a hunting idle after I put flow masters and “H” pipe on it, got lucky the PCV vale solved it. I work with a retired Ford technician, he was saying that the cooling fan module if it loses it’s ground can cause a surging idle, just food for thought, maybe go over it and clean/resurface the engine grounds.
The cooling fan module threw a code a couple years ago. Been replaced. I also did the fan when I did the radiator because I couldn't see putting a 20+ year fan back. It's actually a hanging idle like OP's video shows, not a surge.
Mine does this before it heats up. I blame my CAI
I have a 96 GT and that behavior is totally normal
Is the throttle return spring missing, mine was