Misses when cold, stops missing when warm
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Misses when cold, stops missing when warm
Having a tough time with this one. Check engine light on, P0305 code, cylinder 5 misfire. When I start the engine in the morning or after it has sat a few hours, (keep in mind we are having 100+ degree days) it runs rough and there is an obvious miss. After it reaches full operating temp, usually within 10 - 15 minutes, it smooths right out. I've swapped coils, injectors and installed new plug, no change. 2000 Ford Expedition, 102,000 miles on it. Immaculate, maintenance always kept up, new plugs, almost every sensor has been replaced whether it needed to or not, new O2 sensors. (By new I mean none of the parts have more than 10k miles on them. Any suggestions would be appreciated. I'm wondering if a sensor is not kicking in until it is warm and I really have more than one cylinder misfiring.
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Joined: Dec 2003
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From: Foothills of NC
Very possible that you have a slightly burnt valve. The compression is right on the edge of not being enough until the engine warms up, then the cylinder will fire.
Since #5 is easy to get to, run a compression check on it and #6 to see if they are the same or not.
If you do both you will have a reference from a cylinder that is firing ok.
Since #5 is easy to get to, run a compression check on it and #6 to see if they are the same or not.
If you do both you will have a reference from a cylinder that is firing ok.
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Thanks, I'll give it a test this evening and see what happens. I was hoping it wasn't something like that but it is very possible. I did check all of the plugs and they all looked the same, including #5. I was hoping if I had a compression problem or bad valves that I might detect a different coloring. I do need to do the compression test to find out for sure.
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