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89 Bronco 2, 3k +rpm’s when started cold, no vacuum leaks I can find, I replaced the tps , the IAC and the fuel pressure regulator


Shawn66

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This truck has me stumped, I can find no air leaks the only thing I can think of is that the vac lines are not where they are supposed to be and it’s causing the fast idle, any advice would be great.
 


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rusty ol ranger

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If you had a vaccum leak that big it would be pretty obvious.

89 has no EGR so thats not it.

You sure the throttle isnt sticking? Does the idle come down when warm?

Your new IAC may be bad even.
 

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How does it run otherwise?

Does it settle down to normal idle speeds when warmed up?

How long does it take to settle down?
 

Shawn66

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How does it run otherwise?

Does it settle down to normal idle speeds when warmed up?

How long does it take to settle down?
The idle will not settle at all I am afraid to let it run very long like that, I don’t want to blow the rings
 

Shawn66

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Texarkana, Texas
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1989
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Ford, Bronco II
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2.9 V6
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Total Lift
3inch
Total Drop
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15 inch
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How does it run otherwise?

Does it settle down to normal idle speeds when warmed up?

How long does it take to settle down?
When I got it I had not heard it run at all it had no gas tank and no battery, once I got both connected it did not take long to get it to start and this is what happened, I have a Haynes manual but it does not show me where the vacuum lines go so I can’t verify if they are all routed correctly
 

rusty ol ranger

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When I got it I had not heard it run at all it had no gas tank and no battery, once I got both connected it did not take long to get it to start and this is what happened, I have a Haynes manual but it does not show me where the vacuum lines go so I can’t verify if they are all routed correctly
Is the vacuum hose routing diagram still on the core support? Generally though as long as the vacuum line is hooked to something it shouldnt run that high.

You dont have a stuck PCV valve do you?
 

Shawn66

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1989
Make / Model
Ford, Bronco II
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2.9 V6
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Total Lift
3inch
Total Drop
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15 inch
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I replaced the PCV valve and it helped a small amount but still the idle is crazy high, I pulled the intake and found cracks in 2 places, both of the rear bolts closest to the fire wall that had been repaired with rtv , I am going to get another intake in the next day or so from the salvage yard, I am honestly at a loss if this does not fix the issue, the only thing I have not yet replaced is the O2 sensor if the combination of replacing all of this does not work I think I am just going to cut my losses and sell it there is no sense throwing money at it, I hate to say that because I have put so much into it so far, I have painted it, redid the seats the headliner and new carpet and for this to throw me like this truly saddens me.
 

rusty ol ranger

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My credo
A legend to the old man, a hero to the child...
I replaced the PCV valve and it helped a small amount but still the idle is crazy high, I pulled the intake and found cracks in 2 places, both of the rear bolts closest to the fire wall that had been repaired with rtv , I am going to get another intake in the next day or so from the salvage yard, I am honestly at a loss if this does not fix the issue, the only thing I have not yet replaced is the O2 sensor if the combination of replacing all of this does not work I think I am just going to cut my losses and sell it there is no sense throwing money at it, I hate to say that because I have put so much into it so far, I have painted it, redid the seats the headliner and new carpet and for this to throw me like this truly saddens me.
That cracked intake could for sure be the issue. If not ill be surprised.
 

Shawn66

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Texarkana, Texas
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1989
Make / Model
Ford, Bronco II
Engine Type
2.9 V6
Engine Size
2.9l V6
Transmission
Automatic
Total Lift
3inch
Total Drop
0
Tire Size
15 inch
My credo
Live Free

Shawn66

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Location
Texarkana, Texas
Vehicle Year
1989
Make / Model
Ford, Bronco II
Engine Type
2.9 V6
Engine Size
2.9l V6
Transmission
Automatic
Total Lift
3inch
Total Drop
0
Tire Size
15 inch
My credo
Live Free
Well it took me a while but I figured everything out, the manifold was cracked In-N-Out 2 but 4 places and the big part is the lower intake only had the back 2 bolts in it, not only did that make it run with no power and high rpms but it blew the plenum and the head gaskets, I was foolish for not checking them when I replaced the upper intake but I could not imagine they would not be there, so now I am rebuilding the entire engine which I should have done to begin with.
 


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