4.6 Runs Rough
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Joined: Sep 2003
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From: Kelowna B.C Canada
4.6 Runs Rough
I have a 2001 4x4 ext cab with a auto tranny. It runs rough at a idle when warm and in gear only. It has new plugs fuel, and air filter cleaned maf sensore and throttle body. Help please.
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Joined: Jun 2003
Posts: 186
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From: Biloxi, MS
need more info. does it do after a hard run? where are the rpm's dropping to? has it died out yet? need to check for vac leak, egr system, and check or replace the pcv valve... i'm having the same problem and have replaced a ton of stuff. nothing yet, but i'm working on it. also clean the IAT sensor. does have a light set?
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Account Suspended For Inappropriate For Using Email System To Send Inappropriate Messages
Joined: Sep 2003
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From: Kelowna B.C Canada
No lights come on rpms dont drop. Have not changed pvc valve.Yes it does do it also after hard run.
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Joined: Jun 2003
Posts: 186
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From: Biloxi, MS
at what rpm does the truck idle? does it act as if it is going to die? most all 4.6L have mild rough idle... just a design flaw of ford, but an idle that shakes the truck or almost stalls the engine is a problem... have you put a volt meter on the TPS sensor? it should read between 0.5 and 1.0, i believe.
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Joined: Sep 2003
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From: WY
I had this exact same problem with my Jeep. The driver's side motor mount was cracked.
With it in DRIVE and my foot on the brake, you could feel a wicked vibration. There was no vibration with it in PARK or while driving. I tuned it up, no help. The dealership ran it across the computer and said there was nothing wrong with it. I took it to another dealer who didn't like my brand of spark plugs, and tuned it up again. No help. Finally, I took it to a Mom and Pop garage and he immediately checked the motor and transmission mounts.
With it in DRIVE and my foot on the brake, you could feel a wicked vibration. There was no vibration with it in PARK or while driving. I tuned it up, no help. The dealership ran it across the computer and said there was nothing wrong with it. I took it to another dealer who didn't like my brand of spark plugs, and tuned it up again. No help. Finally, I took it to a Mom and Pop garage and he immediately checked the motor and transmission mounts.
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Joined: Mar 2000
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From: Augusta, GA
I have had the same problem as you have. My truck would just idle real rough almost to the point of dying and then just smooth out with no RPM change. I changed the PCV valve, checked for vacum leaks, did a check on the IAC with multimeter and everything was fine. Then out of the blue last week, I got a check engine light that never got before. I went to Autozone and had them download the code. It turned out to be the forward O2 sensor on the drivers side. After alot of work, I got it changed, and I've driven my truck quite alot and have yet to get the rough idle again. I'm keeping my fingers crossed and hoping this is a perminant fix. I hope this helps and if it does let me know.