Idle issue. Cannot pinpoint
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Idle issue. Cannot pinpoint
Hello everyone. I've been researching and changing parts as I go, but still cannot pinpoint why I cannot fix the problem. Tired of buying parts and it not be the issue. Love the parts though!
Anyway. 1992 F250. 5.8l 4x4. The truck is idling at 1500 rpm. Also it has a rough start, sometimes will need starting fluid to start up.
What I replaced:
IAC, MAP, TPS, IAT, ECT. Also change the plastic vacuum hoses to rubber. Cleaned out upper and lower intake manifolds and added new gaskets. Cleaned out throttle body and added new gaskets.
Now I don't know how important this is. The previous owner deleted the smog pump and also the vacuum hose that is behind the engine (the one that connects to each head).
I've noticed that when I unplug the IAC, the truck starts better and is at rough idle. Which is around 600 rpm. Then when plugging IAC back on, it'll jump back to around 1500 rpm.
I can't figure this out. I've read everywhere and been replacing. But nothing. Maybe I'm looking at the wrong place as the issue. Hoping someone can help.
Anyway. 1992 F250. 5.8l 4x4. The truck is idling at 1500 rpm. Also it has a rough start, sometimes will need starting fluid to start up.
What I replaced:
IAC, MAP, TPS, IAT, ECT. Also change the plastic vacuum hoses to rubber. Cleaned out upper and lower intake manifolds and added new gaskets. Cleaned out throttle body and added new gaskets.
Now I don't know how important this is. The previous owner deleted the smog pump and also the vacuum hose that is behind the engine (the one that connects to each head).
I've noticed that when I unplug the IAC, the truck starts better and is at rough idle. Which is around 600 rpm. Then when plugging IAC back on, it'll jump back to around 1500 rpm.
I can't figure this out. I've read everywhere and been replacing. But nothing. Maybe I'm looking at the wrong place as the issue. Hoping someone can help.
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New User
Joined: Apr 2017
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I changed the egr valve, noticed there was a crack in it. It only drop the idle down to around 1400 rpms. I change the fuel regulator, nothing changed idle. I adjusted the tps and got it around 0.87 volts. Nothing changed idle. Even put it up to 0.99 volts, no idle change.
Now I haven't drove it since I been doing this. I read to drive it for awhile for the computer to 'read'. But I always thought the computer had is already set and there no adjusting needed.
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From: Downingtown, PA
Hello, Sorry to hear you're having idling problems with your F250. I had a similar problem in a Bronco with a 302. The problem turned out to be deposits inside the throttle body not letting the butterfly close all the way. I just sprayed some 2+2 carb cleaner in the bore and the butterfly and cleaned them up real well. It took care of the problem. At least this one is a cheap fix. Good luck with it, George
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Joined: May 2006
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From: Central Mississippi
If you turn the key to run/no start & the check engine light briefly illuminates (bulb actually works) and you can't pull codes with either a reader or manually...
then you most likely have a bad computer.
The leading cause of computer failure is leaking capacitors, but is not a 100% sure thing.
Here's a couple links, mine first, you can search for more. There's a lot:
https://www.ford-trucks.com/forums/1...nd-thread.html
https://www.ford-trucks.com/forums/1...e-problem.html
Although it worked for Robinson in PA, before cleaning your throttle body (I believe you've already done) or adjusting its stop screw (and adding other issues on top of existing problems), bear in mind, it comes with a sticker warning you to NOT clean inside the TB & red paint on the screw to show if it has been moved from factory setting.
then you most likely have a bad computer.
The leading cause of computer failure is leaking capacitors, but is not a 100% sure thing.
Here's a couple links, mine first, you can search for more. There's a lot:
https://www.ford-trucks.com/forums/1...nd-thread.html
https://www.ford-trucks.com/forums/1...e-problem.html
Although it worked for Robinson in PA, before cleaning your throttle body (I believe you've already done) or adjusting its stop screw (and adding other issues on top of existing problems), bear in mind, it comes with a sticker warning you to NOT clean inside the TB & red paint on the screw to show if it has been moved from factory setting.
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