Engine won't idle
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
It's an IAC.
Start the engine and while it is Idling pull the plug off, if the RPM's drop and then it dies, it is working. If nothing changes it is stuck or bad. If it is stuck, take it off and spray carb cleaner in and around the two holes. If you can put 12V on the two pins while it is off and watch for any movement inside, You will also hear a click.
When you take it off you remove the bolts that go into the throttle housing and not the screws that you can see in your photo.
Start the engine and while it is Idling pull the plug off, if the RPM's drop and then it dies, it is working. If nothing changes it is stuck or bad. If it is stuck, take it off and spray carb cleaner in and around the two holes. If you can put 12V on the two pins while it is off and watch for any movement inside, You will also hear a click.
When you take it off you remove the bolts that go into the throttle housing and not the screws that you can see in your photo.
Last edited by subford; Nov 16, 2005 at 11:57 AM.
Fleet Owner
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From: Easton,Ks
Originally Posted by MICBAR
Yes I did remove the plug and the RPM's dropped and then it died. So this means it's working? I need to check the TPS?
The TPS is more than likely OK but to check it, engine off, unplug it and it will have three terminals labeled A, B, & C.
You would need to +5VDC on C and the neg from the supply on A.
The center pin (B) is the output and will read (or needs to be) 1 VDC with the Throttle closed and about 4VDC open. The 1 VDC is the adjustment if it has one and needs be adjusted to one volt.
This is normally done with a breakout box hooked to the EEC and the one volt is at pin #47 (+) and #46 (-).
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
Originally Posted by MICBAR
My F150 recently started running rough, and now won't idle. The gas mileage is terrible! Someone said it was idle sensor, and to unhook battery to reset computer. That didn't help? The engine light stays on too. Will I have to have
someone hook computer up to it? Thanks.
someone hook computer up to it? Thanks.
Here is how you do it.
http://fordfuelinjection.com/?p=13
Good luck
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New User
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Thanks subford....I will try this today after work. I really appreciate you taking the time to help me!!
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Ok...to check the TPS I will need to see if terminal C has +5VDC on it and the neg from the supply on A.The center pin (B) is the output and will read (or needs to be) 1 VDC with the Throttle closed and about 4VDC open? Correct? The 1 VDC is the adjustment if it has one and needs be adjusted to one volt.
Is this right?
Is this right?
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
Originally Posted by MICBAR
Ok...to check the TPS I will need to see if terminal C has +5VDC on it and the neg from the supply on A.The center pin (B) is the output and will read (or needs to be) 1 VDC with the Throttle closed and about 4VDC open? Correct? The 1 VDC is the adjustment if it has one and needs be adjusted to one volt.
Is this right?
Is this right?
I do not know how you are going to do this without a breakout box or a portable 5VDC supply unless you stick a straight pin in the center B wire (GRY/WHT) and the other end of your meter to a good ground.
More than likely the TPS is non-adjustable and you will only be looking for the 1 VDC and 4.8 VDC readings with the key on engine off. If you get them it is OK.
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From: so cal
I am having the same problem with my 90' 351ci. the same symptoms as MICBAR's only the exhaust is really rich. I checked both the IAC and TPS the way subford explained and i found nothing is there anything else that could cause this Im pretty lost.
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
Originally Posted by cody123
I am having the same problem with my 90' 351ci. the same symptoms as MICBAR's only the exhaust is really rich. I checked both the IAC and TPS the way subford explained and i found nothing is there anything else that could cause this Im pretty lost.
I do not think and never thought that the IAC or TPS was his problem but I was just trying to prove to him that they were not his problem without him spending a lot of money.
More that likely he has a bad ECT, ACT, HEGO or MAP sensor.
I would like to see if he has any codes that would point to any of these sensors.
Of course the Thermostat could be stuck open too.
This would apply to your truck also.
Last edited by subford; Nov 16, 2005 at 10:29 PM.
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
Originally Posted by cody123
Does autozone rent out code readers because I dont wanna chance driving the truck with 2001 tags on it.
http://fordfuelinjection.com/?p=13
And here is quick diagram borrowed from Dave Franklin's gallery.
