My F150, 4.6. 73000 miles has an intermitent skip, The engine feels like it is misfiring and there is a lack of power. This usually happens after driving about 10 miles and the truck is under load. There are no "codes". Fuel filter changed less than 10,000 miles. Plugs and wires are OEM. Any help would be appreciated.
Rick

 

when you say skip what does that mean? does the engine hesitate or does the drivetrain slip.

 

The engine misfires and "stumbles". There is some loss of power. As you accelllerate through it, it continues to misfire until you reach the desired speed and let off of the gas.

 

Sounds like your plugs are going bad. Start with replacing the plugs. If no luck, look to your ignition coils.

Good luck.

 

I have found that the new gas with 10% ethanol causes my 2003 Epedition (5.4L) to miss really hard when idling, but just every 60 seconds or so. It also has a sputter when accelerating from a dead stop. I only notice this after I filled up at pump with a 10% ethanol sticker.

Also there is a fuel system cleaner that I have had better luck with than Lucas and it is Red Line SI-1 cleaner. I found it at Autozone and online.

 

I'd start with changing your plugs and wires, and if you want to, your coil packs. Coil packs and wires are easy, spark plugs, not so much. You'll need 4 hours, and a few long extensions.

 

I have about the same skip developed in the last 3 weeks and is vaiable in intensity and intermittant.
It seems to be the transition from idle to low speed med loading on the engine from a stop as well as in the cruise range.
There are no codes even after trying to provoke them with running in the fault condition. I have however found a fault registration with no code assigned using the EDGE tuner scan function that may be the problem if I can get some info on it.
The plugs are about 10k miles old, fuel filter recent, fuel pressure at 35 psi and holding.
Start and idle -ok.
Removed and plugged the EGR line to see if it is related. No.
Inspected the COP for open cracks and moisture, none.
First thing was to put gas anti water additive in to see if it is water in the gas.
Let you know what I find since this kind of problem leaves us hanging.

 

same thing on my 2000 couldnt figure it out. changed all plugs ect like you all and still the little miss but no check light . the other day the light came on and it was a miss on cyl 6 bad cop . even thow they may be ok to the eye they could be bad.

 

1999 4.6's didn't have COP's...

 

sorry didnt know that

 

Haha..its ok. You learn something new every day.

 

i have the same problem right now on my 04 5.4. has fouled out two sets of plugs on cyl 3 and 5 the last set turned bright blue dealer has no idea what is causing it. and it never throws a code did this within 5000 miles.

 

I think it's your COP's - search previouse posts I have made to solve this problem.
Make sure your wiring harness is well away from your accumulator first. Then look to towards the COP's as the culprit. Theres a cheap way to eliminate a COP probem - I would use it lol..

Just read ...

Good Luck!!

 

Sooo.... Whats the cheap way? Im having trouble with #'s 3 and 5. Its funny how earlier there was a post with the same cylinders missing. Im going to look for the cheap way. If there is such a thing.

 

Read thru this post - this is the cheapest way that I know and far less headaches lol. I went thru the same problem and headaches. Hit the links provided in the thread I will post. You will find parts needed and save yourself quite a bit of grief let alone cash..

https://www.f150online.com/forums/sh...d.php?t=245779