misfires only when cold

[docraymund]

Good evening, I had a recent problem with my 4.6 2000 expy. When you start it for the first time it has a misfire and exhaust fumes smell of unburned gasoline. After about 10 mins. of revving, misfire disappears and it runs normally. What could be the problem?

 

[stamp11127]

Any codes?
Your either having an issue with fuel delivery or spark. Maybe both.
Need more info:
How many miles on engine?
When have plugs - wires been changed?
Hard to start after sitting?
Rough idle when cold?

 

[FordandPolaris]

My guess is ignition issue. CoP's and plugs.

 

[DMills]

I have the exact same issue on my 2000. Replaced plugs and CoPs which made for a smoother idle but didn't solve this issue. 107k on my ride. Hoping someone has a solution.


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[FordandPolaris]

Good evening, I had a recent problem with my 4.6 2000 expy. When you start it for the first time it has a misfire and exhaust fumes smell of unburned gasoline. After about 10 mins. of revving, misfire disappears and it runs normally. What could be the problem?

One question I should have asked is do you feel any loss of power during the misfire condition? If not it is probably an exhaust leak, which would go away once the pipes warm up unless its a big one.

I have the exact same issue on my 2000. Replaced plugs and CoPs which made for a smoother idle but didn't solve this issue. 107k on my ride. Hoping someone has a solution.


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If plugs did not solve it, next I would look at vacuum leaks. Do you have a check engine light, and if so can you pull the codes and post them here? Autozone and O'Reilly will both read the codes for free.

 

[docraymund]

Thanks, it only misfires when you first start it say, tomorrow if you start it. Very sluggish and you have to wait for at least 5 to 10 mins. after that it runs fine. No cel and no codes yet for the engine I disconnected the battery and have not driven it far enough for the pcm to complete it's test. But at first start, exhaust smelled like unburned gasoline.