just changed my spark plugs on my 2001 F-150 5.4L ran fine for 3 days now runs rough at low speeds and seems like its missing also the check engine light is on now!! any ideas what caused this?

thanks for any info

 

Have you checked to see what cel code it is?

 

no.... where can I get this done? im an old school mechanic with little knowledge on newer vehicles with computers

thanks for the reply

 

Autozone or Advance Auto will scan for free...

 

Advanced auto will read it for you

 

You can take the truck to Auto Zone or Advance Auto and they can read it for you.
A better choice if you want to keep working on this truck (or anything else younger than 1996) is to get a reader. They range in price from about $ 49 to $300, depending on what features you get.

I'd bet on at least one bad coil or possibly a coil not seated properly after reinstall. New plugs can reveal weak coils.... Either one will be indicated by a Misfire code on one or more cylinders.

 

thanks people, i'll have it checked tomarrow and will post back

 

Is the light on steady or flashing? If it is steady, it is not a misfire. The light will flash for a misfire.

 

a code reader or better yet a code box hooked to a pc is a great tool to have

 

just got back from autozone and guy told me its against the law so they don't scan anymore.............im in california

thanks


re:yea its true what can I do next?
thanks