So I have had a misfire in number 5 and a random misfire for over a month after replacing all spark plugs and coil packs. I'm assuming I got a bad plug but havent looked into it yet, just dealing with the misfire at the moment. Yesterday, while driving, I accelerated to pass a vehicle, and the misfire got really bad, like the whole truck was vibrating. I pulled over to shut off the engine to let it sit for a minute. After sitting for a minute, I tried to start it, but it cranked a couple of times and acted like the battery was dead. Tried a few more times and still the same behavior. I was able to jump start it, but as soon as the cables were unhooked, it acted like it wanted to die, then it did die as soon as I put it in reverse. Thinking it was the alternator, we got a freshly charged battery, hooked it up, and it started but was running very rough, misfiring horribly, like it was before I originally shut the engine off. I made it approximately 5 miles on the freshly charged battery when I got to a red light. When I came to a complete stop, the battery died. We jumped it again, but when we took the cables off and I put it in drive it died. Had it towed home where we charged and tested my original battery, it is holding a charge and tests good. The next day we checked the alternator and it is working properly and putting out the correct voltage. It is now running without dying and still has the original misfire. Anybody know what would cause this behavior?

 

if you jump it and it starts, but wont start on the installed battery, then the installed battery is not putting out the required voltage.. If the battery is GOOD... then i would look at the battery cables themselves.. Maybe had some oxide corrosion and you scrapped some off during the battery change... I would clean the cables..

 

and definitely fix the mis-fire condition. do you have a CEL ? how about a red battery light ? any codes ? what was the Alternator output ?

 

X2 do you or have you had a CEL (check engine light), WRENCH light, or Battery looking symbol on the instrument cluster? Sounds like you you migth have a intermittant alternator issue. Any chance you can hook up a OBD II code reader? O'Reilly's does it for free, I am sure Auto Zone migth also.

That might also give you a code on a bad spark plug/coil pack for the miss. The 5.4 is bad for that and cam phase sensors/timing chain issues.


This guy is pretty smart about all the 5.4 miss fire issues. https://www.youtube.com/user/FordTechMakuloco

 

Thank you guys for the response, my dad finally figured it out. It's an issue with the timing chain that has caused other problems as well.

 

Yes as I understand it and unfortunately the 2004-2008 Ford truck 5.4 3 valve has a bad rep and can tend to have a lot of engine issues. Some are related to the use of plastic timing chain tensioners. And when oil changes are not done as required, they can get hot and brittle. And when pieces break off they can clog the oil tube pick up screen. And that can lead to a lack of proper timing and causing all sorts of other issues.

And the timing chain gets loose and can be slapping on the aluminium timing chain cover (start up tick) and that leads to aluminium getting into the complete oil system. Also it being a dual over head cam engine (meaning 2 cams per side and that means 2 timing chains)...and the cam phasers/sensors VCT...bla bla bla are all tied into it, or some such stuff like that. And all that can lead to needing a bunch of $ work and a Lock Out Cam Phasers/3V VCT Elimination Kit and or some other things.

. https://www.freedomracing.com/4-6l-5...BoCuHkQAvD_BwE

Just a painful remider to change your oil as required. Parts cost are painful, labor to replace the parts are just a painful.