91 460 confusion
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Post Fiend
Joined: Mar 2011
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From: Backwoods of Snowflake AZ
91 460 confusion
Ok so we have a 91 f250 460 that keeps idling high. Idles at 1300-1500. When put in gear it is fine. Every part seems to help.
Pulled the codes only onss are for idle to low???
O2 sensor system lean and egr valve not opening.
So far a new iac valve which when you unplug no difference. getting power to it I already checked.
Adjusted the TPS correctly and brand new fuel pressure regulator. New fuel pumps new map sensor, checked the vacuum lines and no more leaks. Put a new computer in but that was because of another issue. The previous owner did loosen the idle screw but that should lower the idle?
Also put a new ECT in.
Any help is appreciated
Trav
Pulled the codes only onss are for idle to low???
O2 sensor system lean and egr valve not opening.
So far a new iac valve which when you unplug no difference. getting power to it I already checked.
Adjusted the TPS correctly and brand new fuel pressure regulator. New fuel pumps new map sensor, checked the vacuum lines and no more leaks. Put a new computer in but that was because of another issue. The previous owner did loosen the idle screw but that should lower the idle?
Also put a new ECT in.
Any help is appreciated
Trav
Lead Driver
Joined: May 2011
Posts: 5,775
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I think you have a vacuum leak. Plug throttle body with rags, you should be able to find it rather easily.
Vac leak would explain lean code also....since your egr is not opening either, I'd trace it's vac source first.
Vac leak would explain lean code also....since your egr is not opening either, I'd trace it's vac source first.
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Post Fiend
Joined: Mar 2011
Posts: 10,080
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From: Backwoods of Snowflake AZ
No change at all it runs at the same room.
I have looked and looked for vacuum leaks and can't find any not sure how else to find any.
All the vacuum lines are brand new. I may be wrong about this but I think the run lean came after the new fpr however I didn't check codes till after adjusting the TPS.
Trav
All the vacuum lines are brand new. I may be wrong about this but I think the run lean came after the new fpr however I didn't check codes till after adjusting the TPS.
Trav
Lead Driver
Joined: May 2011
Posts: 5,775
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If it runs with the iac unplugged, it must be a vac leak (I thought you said above that you unplugged the iac and it ran)
Stuff rags into the throttle body, all the air will be going through the leak.
Stuff rags into the throttle body, all the air will be going through the leak.
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Lead Driver
Joined: Jul 2007
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From: Rhode Island
The good news is we can stop worrying about electrical/sensor issues. Your problem is either a stuck IAC valve, or a vacuum leak. First thing I would try is tapping on the IAC valve with a hammer. If there's still no change, remove the IAC valve and verify the plunger inside moves freely.
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Mountain Pass
Joined: Dec 2006
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From: Osburn, ID
My similar truck idled the same. I chased everything. Finally changed the throttle body and it now idles 600-700. I had already changed all the gaskets that could leak on the throttle body prior. So I assume the leak was coming from the throttle shaft itself.
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Post Fiend
Joined: Mar 2011
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From: Backwoods of Snowflake AZ
Sorry for the late reply been super busy with other things.
So today stuffed rags in the intake and no change. Started looking and noticed the egr valve is not fully seated on the intake na 1\4in gap. So tried tighten the bolt no luck it is stripped out. Going to fix it with a longer bolt so that we can tighten it. Hopefully this will fix the issue.
Trav
So today stuffed rags in the intake and no change. Started looking and noticed the egr valve is not fully seated on the intake na 1\4in gap. So tried tighten the bolt no luck it is stripped out. Going to fix it with a longer bolt so that we can tighten it. Hopefully this will fix the issue.
Trav
Lead Driver
Joined: May 2011
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You can spray ether, carb cleaner, or brakleen around the penetrations of the intake in order to isolate it. Also check pcv valve, if it's stuck open it is a gaping leak. Having rags in the intake while spraying helps.
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Post Fiend
Joined: Mar 2011
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From: Backwoods of Snowflake AZ
Trav