Rough idle 250 v10

ford
f250

#1

2004 ford f250 superduty v10, truck has a cold run miss,no matter the temp.(0deg. or 100 deg.) when i start truck it misses for about a mile or so until temp. rises,after that it runs fine all day even if i park it for a few hours,next day same thing.i have changed all 10 plugs,gas filter,air filter,cleaned mpf censer,throttle body. also it shows no codes,and there are no codes in history.HELP


#2

One guess here is . . vacuum leak ?
Like intake manifold gaskets. expanding at running temp plugs that cold leak.


#3

Flaky coolant temperature sensor?


#4

I think this is a fuel problem. It could be the ignition, but ignition system problems tend to occur when the engine is hot, the opposite of this one. Still, good idea for OP to verify the battery is good , holds charge, passes a load test, and has clean connections to the posts. One idea, charge the battery overnight with a battery charger and see if the problem goes away for that first drive of the day. That would indicate a battery problem. OP could ask their shop to do a visual test for a good, hot spark when the engine is cold too.

On to the fuel. When the engine is cold it requires a richer mixture. So probably something wrong there. It could be too rich, or too lean. More likely the latter, caused b/c the computer is thinking it is injecting more gas than actually gets injected. Clogged fuel injector for example. Or low fuel pressure. Shops have ways to test for both.

A cylinder with low compression might cause this symptom too.