missing problems
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missing problems
I have a 2000 f150 with a 4.6L engine. I am having trouble with the engine maybe. When I am driving done the road it runs fine. After it warms up and I am traveling down the road and go to slow down to around 35 or 45. When I get back into the throttle hard or soft it has what seems to be a miss or hesitation. I am not sure what could be causing this. I have changed one coil pack and all spark plugs. could it be an injector or another coil pack? any ideas will help. it is not showing and OBD codes. any ideas.
David
David
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Joined: Oct 2005
Posts: 2,209
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From: Louisville, Kentucky
Originally Posted by Bluegrass 7
<TABLE><TBODY><TR><TD vAlign=top width="100%">One coil has shorted turns reduceing the output. When in cruise mode, the EGR opens, the fuel is cut back and the ignition timing advances.
Under these conditions the A/F ratio is very lean, the faulty coil fails to fire reliably and you feel the miss/stumble. The fault is not present long enough to register history and cause the PCM to see what cylinder it is, so you nor anyone can tell which one it is. The PCM keeps clearing the fault table when the fault is no longer present until the next time it occurs. Swapping coils around does nothing to find the fault except change to a different cylinder's fault table for the same action all over again.. Don't get to excited, not to many shops know this yet.
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Under these conditions the A/F ratio is very lean, the faulty coil fails to fire reliably and you feel the miss/stumble. The fault is not present long enough to register history and cause the PCM to see what cylinder it is, so you nor anyone can tell which one it is. The PCM keeps clearing the fault table when the fault is no longer present until the next time it occurs. Swapping coils around does nothing to find the fault except change to a different cylinder's fault table for the same action all over again.. Don't get to excited, not to many shops know this yet.
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I pulled this quote from a similar thread. Bluegrass has a lot of experience with this. You need to take the truck to your dealer and have the coils stress tested. Good luck!
