I have a 2001 F150 4x4 with a 4.6L, 5-speed. Engine had a bad miss, changed plugs with Motorcraft platinums. Did not help. My cousin looked at the truck and suggested a fuel pump. Replaced the fuel pump and it helped but miss is still there. Pulled wires on injectors and determined #4 was not firing. Swapped #4 COP and Plug with #2 COP and plug. No change. Installed a hotter plug in #2 and ran smooth while idling for 15 min. After a quick trip up the road still slightly missing. What should I do now? Install hotter plugs for the rest of the cylinders or replace the coil pack on #2. Any feedback woud be greatly appreciated.

 

Oh and after swapping the COP and plug from #4 to #2, #2 was not firing correctly and #4 was fine. So not injectors? Right?

 

Discribe how the miss presents it'self.
As a full time miss for which you should have a code or under certain driving conditions such as in OD and light throttle that comes and goes.

 

You need a new COP.

 

im with GLC sounds like a COP prob. can you still get the set from global for 90 bucks for all 8?

 

I have some old coil packs laying around. I will try switching them and let ya know if that fixes it.

 

Switched coil packs. No change. Only misses under load when its cold. After it warms up it misses at idle.

 

If you have a (solid) miss, there should be a code set that will tell you what cylinder it is.
How the system detects it is by actually measuring the crank rotation time and compairing it with the rest of the cylinders within rpm limits set in the program.
Makes little difference what causes the miss, it's time related for crank rotation.
Use a Scanner to see if one is set and possibly avoid all the extra work trying things and possibly getting confused with faulty old parts.
Good luck.

 

Why did you replace the pump ?

You need to let miss long enough to set DTC in the KAM. You have Coils on that engine, not packs. Does your CEL work ? Is it illuminated now? Has it ever blinked then shut off ?

 

I have an edge programmer installed in the truck and I checked the codes last night. It did not retrieve any codes. And Jbrew yes I have COP's on my truck it is a 2001 model. A hotter plug did make it run better. Should I replace all the plugs with hotter ones?

 

No, stop messing with the plugs, your not built or blown lol.

Return to stock with device. Once your in stock mode, -disconnect the battery, both sides for one half hour. Reconnect POSITIVE FIRST.

Tell me how it runs.

 

I agree, stop with the plug heat range changes.
A stock motor never needs this consideration.
Normally the plugs will look a little whiteish as it is because the OX sensors keep the A/F ratio spot on so the plugs are clean looking for color.
Using a hotter plug is not accomplishing anything in a fault free stock motor.
Do not apply the old carburation thinking to an FI motor. There is no compairison.
The EDGE monitor/tuner does not have "all" the codes and discriptions to display in it's program so you may miss some, at times.
Good luck.

 

NOW you tell us! Return it to stock and remove the programmer. If it runs fine, the programmer or the tune you are using is bad.

 

Sorry for taking so long with the reply. Went back to stock and switched another coil pack. Ran great for about 2 weeks. Now the miss is back. Any ideas? Should I replace all the coil packs or injectors?

 

Yea, - I wouldn't run coil packs on that one, -you don't have the drivers to run them. - Unless your an early 2000 model w/2001 engine ..?? Two completely different ignition systems

Yea, they started using dedicated coils , - late 2000 I believe. So, your coils don't run a pack of cylinders, - you know ? -They are however responsible for just one. When they're not eF'en off

Good Luck.