misfire when cold

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firefighter407

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I got a 99 expedition with the 5.4, My problem is when I start the truck when it's cold I have a misfire until the engine is at normal operating temp.

I changed the plugs ( motorcraft sp-479) and coils ( ebay from uneek) last month. it ran fine till last week.

the check engine light came on and gave a misfie on cyl. #5, I changed the coil and still the same. Any ideas or suggextions?

Thanks
 

KWT2000

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pull the plug on #5 and check the gap also check the pigtail to the coil its self... how cold are we talkin, if its freezing crappy gas or a little water could cause a weak injector of act up aswell
 
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firefighter407

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pull the plug on #5 and check the gap also check the pigtail to the coil its self... how cold are we talkin, if its freezing crappy gas or a little water could cause a weak injector of act up aswell


yup just checked the gap it's about .050, checked all the connectors, changed the plug again, put the old COP, checked all vacuume hoses that I could get at.

Now it even has the miss after the engine has warmed up, at idle it seems fine but if I put it in drive and hit the gas i misses or if n neutral and i give it a quick shot of gas it hesitates rpm comes up and it misses.

Temp out side is average fall weather in canada (12 C today)

any more suggestions? Thanks
 

KWT2000

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theres only three things that can cause a missfire on a specific cylinder... no spark, no fuel, no or low compression... it is possibile to have a bad spark plug i see that everynow and again
 
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firefighter407

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finally figured out the problem, also had misfire on cyl.# 2,3 and 4. but only thing I can't figure out is why the check engine light didn't come on?. and is it ok to mix coils ( I have 3 new ford COP 1 old and 4 from Uneek)?
 
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