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99 explorer idle issues

Lee's Automotive

Git-R-Done
Elite Explorer
Joined
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Messages
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Location
United States
City, State
Alabama
Year, Model & Trim Level
99 Explorer XLT 4.0 SOHC
Hello guys I have a 99 explorer 4.0 SOHC that is having some weird idle issues it idles way too low like around 400 to 500 RPM and I have replaced the IAC Valve DPFE Sensor TPS sensor and cleaned the MAF I've also replaced the fuel pump and fuel filter along with the intake manifold gaskets
 



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@Lee's Automotive

Have you tried adjusting your TPS to get your voltage to right around, if not even a little over 1V?

Your computer screen says your RPM's are 656 and TPS is .94V
 






@Lee's Automotive

Have you tried adjusting your TPS to get your voltage to right around, if not even a little over 1V?

Your computer screen says your RPM's are 656 and TPS is .94V
I adjusted the idle air control valve screw on the valve itself and the idle is about 750 but when the ac comes on its about 1100rpm
 


















I adjusted the idle air control valve screw on the valve itself and the idle is about 750 but when the ac comes on its about 1100rpm

@Lee's Automotive

The rise in RPM with A/C is on purpose -

It's "there" for Automatic Transmission Ex's so they don't stall/bog down at a stoplight, when your foot is on the brake, and the A/C is on.

With that said, from memory, it should only be about 900 - 1,000 rpm w/ the A/C on on an Automatic Ex.
 






After the computer learns the idle it should rest at 656
It also has to learn how much to boost idle for the AC
In a few days it will level out
From your data I'd be looking for a vacuum leak

More data please
 






First picture is key off and second picture is WOT and third pic is key on engine off
20210212_104540.jpg
20210212_111159.jpg
20210212_111222.jpg
 


















This is an update of current issues and progress
 






Idle seems high
It looks smooth
Its a 6cyl it won't be smooth like a v8
Idle is definitely to high

You need a Motorcraft t stat

My advice is turn the screw on the back of the iac back a 1/8 turn OUT to fix that high idle
Then fix your vacuum leak that's causing your low idle root problem
 






Idle seems high
It looks smooth
Its a 6cyl it won't be smooth like a v8
Idle is definitely to high

You need a Motorcraft t stat
Ok what should the idle be?
 






I'm gonna make a vid for you in a few hours
To help show you what to look for
And how to fix it
Idle should be 656 after warm up
In your for scan pic you had the desired rpm not actual rpm
The computer wants to be at 656 not 800
 






Ok thanks so much
I'm gonna make a vid for you in a few hours
To help show you what to look for
And how to fix it
than
 






Idle seems high
It looks smooth
Its a 6cyl it won't be smooth like a v8
Idle is definitely to high

You need a Motorcraft t stat

My advice is turn the screw on the back of the iac back a 1/8 turn OUT to fix that high idle
Then fix your vacuum leak that's causing your low idle root problem
Does it have to be the motorcraft thermostat or would a stant or motorad thermostat work?
 






@Lee's Automotive

Don suggested a Motorcraft - and no denying that's Top Dog - and of course there's always the dealer for OEM.

If it's a customer car, pass the cost on, hit goal 1st time, and thus lessen your workload and get your customer their Ex back quicker.

Now if your only choices are Stant or Motorad - my choice would be Stant.

I've never had a problem with them (but now that I said that in an open forum) ;)
 






@Lee's Automotive

Don suggested a Motorcraft - and no denying that's Top Dog - and of course there's always the dealer for OEM.

If it's a customer car, pass the cost on, hit goal 1st time, and thus lessen your workload and get your customer their Ex back quicker.

Now if your only choices are Stant or Motorad - my choice would be Stant.

I've never had a problem with them (but now that I said that in an open forum) ;)
I'm on a tight budget and the motorcraft thermostat is 30 so I will go with stant
 






I'm on a tight budget and the motorcraft thermostat is 30 so I will go with stant

No doubt -

I didn't know if it was your Ex or a customer's ride.

Yeah - $30 VS $7 - that's a no brainer in my book - given Stant has always worked for me.

That sound you hear is me knock on wood :thumbsup:.

PS - Gates for hoses -
 



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No doubt -

I didn't know if it was your Ex or a customer's ride.

Yeah - $30 VS $7 - that's a no brainer in my book - given Stant has always worked for me.

That sound you hear is me knock on wood :thumbsup:.

PS - Gates for hoses -
Should i go with 190 or 192
 






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