Fox 1993 FOX High Idle

Noobz347 · Dec 31, 2024

I could not for the life of me remember. I have an image in my head of a seal but don't remember what it's from (Ford, Chevy, GM, other).

Noobz347 · Dec 31, 2024

I just stole this from another thread (funny how that works):

This is where your leak would be.

AeroCoupe · Dec 31, 2024

There is a seal on the TPS but it’s a moisture seal more than anything.

90sickfox · Jan 1, 2025

The egr usually wisps a little smoke at that orange seal duri g a smoke test. Not saying it isn't bad. The most common area for a vacuum leak is the hose that runs under the intake behind the distributor. That hose is hard to see and to get to. ( should be seen in a smoke test.

I seem to remember an o ring type seal under the factory tps. Its been a very lo g timesince I've seen one though. I know my aftermarket one doesn't have one on it...and hasn't for many years. A very small amount of snoke is acceptible from the throttle shaft wnen smoke testing.

TheJay806 · Jan 4, 2025

Replaced the EGR valve and boom, idle immediately dropped down to normal. Problem solved. Thanks everyone. I did a smoke test one more time to double check and no leaks.

TheJay806 · Jan 8, 2025

Mustang5L5 said:
But stock TBs have the hole present, so hard to say if he’s looking at someone’s band-aid fix, or just a stock TB blade with a hole present.

Stoxk hole here

Any idea what size this hole is? Could i put a lock screw and bolt in here or is it to dangerous?

TheJay806 · Jan 9, 2025

Mustang5L5 said:
But stock TBs have the hole present, so hard to say if he’s looking at someone’s band-aid fix, or just a stock TB blade with a hole present.

Stoxk hole here

Can I block or lock nut and bolt this hole? Or is it to risky and better off getting a new throttle body?

KRUISR · Jan 9, 2025

To test if blocking holes improves things, sure. Could do some JB Weld or some silicone at least to test it. If it works a more permanent solution can be figured out.

Noobz347 · Jan 9, 2025

There is nothing you need to do with that hole IMO. It's there from the Factree.

Mustang5L5 · Jan 9, 2025

The hole is not the issue. It’s supposed to be there. Blocking it may actually cause the throttle to stick slightly.

If you want to test it to see if it’s the cause of your issue, stick a nice peice of duct tape firmly across it. If the idle is still high your problem is still elsewhere

TheJay806 · Jan 14, 2025

I followed these instructions for resetting the idle etc. it worked like a charm. On start up it now idles at 750. After driving for a bit it moves back to 1000rpm. If I shut it off and start up a little later, back to 1000rpm. Is this normal? Or would this be a faulty IAC? I have a new IAC I can throw on and do the procedure again if need be?

"
Clear the computer's idle memory by disconnecting the battery for 20+ minutes.

-Disconnect the Idle Air Bypass solenoid (IAC)
-Reconnect battery
-Start engine and set idle speed to desired RPM with idle screw on throttle body
-Turn off engine and reconnect the air bypass solenoid
-Set TPS voltage between 0.90 - 0.95 volts with a digital volt meter
-Start engine and let it idle for 2 minutes with no accessories on.
-Turn off engine for two minutes
-Start engine again and run for 2 minutes with every accessory turned on.
-Turn engine off again.

"

KRUISR · Jan 14, 2025

The steps you did were pretty good, but you missed a key one near the beginning.

When you disconnect the IAC, you need to disconnect the SPOUT connector on the distributor as well. If you don't, the PCM will keep adjusting the timing to improve idle while you are making adjustments and you will be chasing your tail trying to get it lower.

Also, when you set the idle, set it as low as it will still keep running - it will not likely run smooth but it just needs to keep running. I have gotten the idle down in the 550 - 650 rpm range on this step. The lower you can get it, the more range the IAC has to work with to maintain idle when you are done with the process.

The rest of the steps you did looks good.

TheJay806 · Jan 14, 2025

KRUISR said:
The steps you did were pretty good, but you missed a key one near the beginning.

When you disconnect the IAC, you need to disconnect the SPOUT connector on the distributor as well. If you don't, the PCM will keep adjusting the timing to improve idle while you are making adjustments and you will be chasing your tail trying to get it lower.

Also, when you set the idle, set it as low as it will still keep running - it will not likely run smooth but it just needs to keep running. I have gotten the idle down in the 550 - 650 rpm range on this step. The lower you can get it, the more range the IAC has to work with to maintain idle when you are done with the process.

The rest of the steps you did looks good.

So the only way I could get it to work is by starting the car with the IAC already disconnected, can I do the same with the spout?

KRUISR · Jan 14, 2025

Yes. That is how you set the timing on our cars too - with the SPOUT disconnected, then starting.

TheJay806 · Jan 15, 2025

I re did this procedue, removing the SPOUT this time. The idle again dropped down of course, I had the idle screw backed out and then adjusted to "set" the idle. Idled perfect. Then took it on the road, and at the light, idle sits at 1000rpm.

Mustang5L5 · Jan 15, 2025

When it idles up, unplug the IAC.

What happens?

TheJay806 · Jan 15, 2025

Mustang5L5 said:
When it idles up, unplug the IAC.

What happens?

I'll try again tonight, but typically before, If I unplugged the IAC while the engine was running it did nothing. No change. That was before actually getting the idle lower though. I've smoke tested and no vac leaks, EGR was leaking previously, I replaced it. EGR is installed and connected but hoses are capped off.

But, if i let it sit for while, and go back and restart it, it'll idle perfect again. It just seems like once I start driving, on the hwy especially, then the idles stays at 1000

Mustang5L5 · Jan 15, 2025

can you provide additional info on the car? There are a few other things that would cause this depending on a few things.

What year is this car? Original mass air car? Have you dumped codes? Do you know if your VSS is hooked up? Is this an AOD-to-T5 swap car?

There are some electrical gremlins with swap cars with mismatched ECUs and stuff that can also cause idle hang.

Fox 1993 FOX High Idle

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

AeroCoupe

lube between the nut and the face. I know my lubes

90sickfox

Wasn't a pretty sight...and I've got big hands

TheJay806

Member

TheJay806

Member

TheJay806

Member

KRUISR

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

Mustang5L5

That is…until I whipped out my Bissell

TheJay806

Member

KRUISR

TheJay806

Member

KRUISR

TheJay806

Member

Mustang5L5

That is…until I whipped out my Bissell

TheJay806

Member

Mustang5L5

That is…until I whipped out my Bissell

Similar threads

Fox 1993 FOX High Idle

Stangnet Facilities Maint Tech... Er... Janitor

Stangnet Facilities Maint Tech... Er... Janitor

lube between the nut and the face. I know my lubes

Wasn't a pretty sight...and I've got big hands

Member

Member

Member

Stangnet Facilities Maint Tech... Er... Janitor

That is…until I whipped out my Bissell

Member

Member

Member

That is…until I whipped out my Bissell

Member

That is…until I whipped out my Bissell

Similar threads

Privacy & Transparency

Privacy & Transparency