Rough Idle and Check Engine Codes
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Junior Member
Joined: Aug 2009
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Rough Idle and Check Engine Codes
Newbie here looking for some help with my 02 F150 V6.
For the past few months I have been dealing with a rough idle and constant engine codes. The codes I have found are p0174, p0171, p1131 and p1151.
At first the truck was running perfectly fine - even though the check engine line was on. Over time however it has developed a pretty rough idle when sitting still. On top of that when I put it in reverse it really starts to thrust back and forth (the rpms jump back and forth between 500-1000 rpms and the truck jerks violently). When it does this I can put it in neutral and rev it up a bit and it will settle down. The truck still runs great on the open road and as long as my foot is pushing the accelerator its fine. It's just isolated to the idle.
I have read loads of stuff on this forum for these codes so I have already tried many things lincluding:
1) I replaced the fuel filter
2) Replaced the MAF
3) Replaced both forward O2 Sensors
4) Replaced the top large Plenum O Ring gasket
5) Replaced the lower "figure 8" Plenum O rings
6) Replaced the Plenum isolator bolts with the "green trim" types
7) Checked all the PCV vacuum hoses and elbows for leaks and found none
8) Sprayed carb cleaner around intakes with no indication of any leaks around plenum
I am running out of ideas. It seems logical that I have a vacuum leak but I just can't find any evidence of anything leaking. I have not done anything to the EGR or DPFE yet except pull the vacuum tube off of the EGR while engine running which didn't seem to make any difference to idle.
I am running out of ideas and almost to the point where I will have to bite the bullet and take it to the dealer. Anyone have any other ideas?
For the past few months I have been dealing with a rough idle and constant engine codes. The codes I have found are p0174, p0171, p1131 and p1151.
At first the truck was running perfectly fine - even though the check engine line was on. Over time however it has developed a pretty rough idle when sitting still. On top of that when I put it in reverse it really starts to thrust back and forth (the rpms jump back and forth between 500-1000 rpms and the truck jerks violently). When it does this I can put it in neutral and rev it up a bit and it will settle down. The truck still runs great on the open road and as long as my foot is pushing the accelerator its fine. It's just isolated to the idle.
I have read loads of stuff on this forum for these codes so I have already tried many things lincluding:
1) I replaced the fuel filter
2) Replaced the MAF
3) Replaced both forward O2 Sensors
4) Replaced the top large Plenum O Ring gasket
5) Replaced the lower "figure 8" Plenum O rings
6) Replaced the Plenum isolator bolts with the "green trim" types
7) Checked all the PCV vacuum hoses and elbows for leaks and found none
8) Sprayed carb cleaner around intakes with no indication of any leaks around plenum
I am running out of ideas. It seems logical that I have a vacuum leak but I just can't find any evidence of anything leaking. I have not done anything to the EGR or DPFE yet except pull the vacuum tube off of the EGR while engine running which didn't seem to make any difference to idle.
I am running out of ideas and almost to the point where I will have to bite the bullet and take it to the dealer. Anyone have any other ideas?
Member
Joined: Jun 2007
Posts: 16
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I had this same problem on a 2004 model (new body style). I cleaned the Throttle Body and it fixed the problem, smooth idle now. FYI, I actually took my TB off to clean it, I don't know if that is necessary but it cleaned it really good.
Good Luck!!!
Good Luck!!!
