o2 Sensors?
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Junior User
Joined: Oct 2005
Posts: 89
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From: South-east Idaho
o2 Sensors?
I have an 01 F350 with the 5.4 liter. My problem is that the truck runs good while warming up, but when it gets to operating temp, it starts running rough. I don't get any check engine light. My research tells me that it is a bad o2 sensor. I found 2, one just below each exhaust manifold, and replaced both of those. I have read that there should be a least 3 sensors with one downstream of the catalytic converter, but I can't find one on the truck. Is this the case or can there be only two? After replacing the two I found the truck is still running rough when warm.
Could the problem be something else? All help is greatly appreciated.
Could the problem be something else? All help is greatly appreciated.
Logistics Pro
Joined: Aug 2007
Posts: 3,974
Likes: 17
From: Millersburg, OH
There is no O2 sensor aft the cat. You'll just have the two on the y-pipe. 1999+ F250/F350 are over 8500 GVWR and or not required to be ODB II emission compliant. Basically they have ODB I system with an ODB II interface.
You may have a COP that is misfiring. If you have a scanner that reads pending codes hook it up and check for misfires.
Also clean the MAF sensor. Probably not it but doesn't hurt. Others will hopefully chime in with more ideas.
You may have a COP that is misfiring. If you have a scanner that reads pending codes hook it up and check for misfires.
Also clean the MAF sensor. Probably not it but doesn't hurt. Others will hopefully chime in with more ideas.
Post Fiend
Joined: May 2006
Posts: 10,007
Likes: 4
From: Central Florida
Yes, the coils can fail once warm but give little sign otherwise. You might try pulling each one and looking at the boots. Inspect them for color changes and cracks that could arc to the heads.
Closed loop glitches are usually o2 related, but it could also be a sticky IAC or EGR valve. Both can cause hesitation, but I am not sure about a miss.
Closed loop glitches are usually o2 related, but it could also be a sticky IAC or EGR valve. Both can cause hesitation, but I am not sure about a miss.
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Schwinn240
1987 - 1996 F150 & Larger F-Series Trucks
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Mar 25, 2010 06:57 PM
