99 f150 rough idle after tune up
#1
99 f150 rough idle after tune up
Hey guys I'm new here and need some help. I just bought a 99 f150 with a 4.6 in it. I just put plugs wires and coils on it and it is still running rough most noticeably at idle. I have also put a new fuel filter and idle air control valve, cleaned the throttle body. Any help with this would be appreciated.
Last edited by Bgmik1313; 06-29-2015 at 08:23 PM. Reason: More work done
#3
I sure haven't. It's got me puzzled. I've noticed that it idles around 600 rpm and the miss doesn't show on the tach but it runs rough through about 1500 rpm then seems to smooth out. It's getting really bad fuel mileage also. I used almost half a tank in around 100 miles.
#4
#6
I had the exact same issue, and I finally fixed the problem. When I changed coils I used accel. They were putting out spark. But they weren't right. Switched to motorcrAft coils and all is well. My friend scanned my truck. I was misfiring on cylinders 4,5,8. This was very noticeable while doing a very light brake torque. Never threw an engine code. New motorcraft coils and the problem went away
#7
I had the exact same issue, and I finally fixed the problem. When I changed coils I used accel. They were putting out spark. But they weren't right. Switched to motorcrAft coils and all is well. My friend scanned my truck. I was misfiring on cylinders 4,5,8. This was very noticeable while doing a very light brake torque. Never threw an engine code. New motorcraft coils and the problem went away
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#8
#9
Thanks. I'll check into it. The dealership wants $90 to scan it. I guess it might be worth it.
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