5.4 still runs rough
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Joined: May 2003
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5.4 still runs rough
My 99 F250SD 5.4 w/158k still runs rough intermittantly. It has done this ever since I bought the truck 1.5 yrs ago w/130k on it. I have changed the plugs, COPs, fuel filter,air filter, etc...
I had some luck when I changed the COPs, but I did them one at a time b/c I never got a fault code...just kept moving the new one around until the misfire disappeared(buying all 8 at once was too$$). All are replaced now. It misses below 2000 rpm, esp in OD. It finally threw a code of 401-EGR insuffcient flow detected. I cleaned the EGR valve...didn't help.
Also-is 10-11 mpg bad with an even mix of highway and city driving? EGR problems can be assc. w/ bad mileage. The truck is a longbed extra cab 4x2 w/3.73 open diff usually unloaded and not pulling anything.
Thanks,
Chris
99 F250SD
97 F250LD
I had some luck when I changed the COPs, but I did them one at a time b/c I never got a fault code...just kept moving the new one around until the misfire disappeared(buying all 8 at once was too$$). All are replaced now. It misses below 2000 rpm, esp in OD. It finally threw a code of 401-EGR insuffcient flow detected. I cleaned the EGR valve...didn't help.
Also-is 10-11 mpg bad with an even mix of highway and city driving? EGR problems can be assc. w/ bad mileage. The truck is a longbed extra cab 4x2 w/3.73 open diff usually unloaded and not pulling anything.
Thanks,
Chris
99 F250SD
97 F250LD
Freshman User
Joined: Mar 2003
Posts: 26
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Oxygen Sensors
I will recommend to get a good scanner (Autoxray 5000 or 6000) and check for the oxygen sensors, voltage reading. I had similar problem and it was caused by the oxygen sensors located after the catalytic converter.
Good Luck!
Ponsik
Good Luck!
Ponsik
New User
Joined: Nov 2003
Posts: 10
Likes: 1
Check for plugging
Check for plugging downstream of the EGR valve. This picture shows just how bad it can be. Both me (98 expedition) 110k and my brother in law (98 F150) had same problem. Codes showed low EGR flow. Tried all the suggestions first, bought new DPFE switches, Cleaned EGR valve and exhaust manifold tube, etc. All the time it was this simple ugly plugging. Relative easy to clean after removing throttle body.
A business card is inserted in TB so you can see black sludge ball. There are two one for each port and there shadows on the card. Passage ways totally plugged. Used coat hanger to clean.
A business card is inserted in TB so you can see black sludge ball. There are two one for each port and there shadows on the card. Passage ways totally plugged. Used coat hanger to clean.
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