4.6 misfire on #6
 

i have a 98 150 4.6 romeo if it makes a differance started missing when it shifted into passing gear but has progressively got worse to missing at a idle changed coil pack checked wires for short pulled plug looked a little chared but not bad whats next

also i cleared the codes and cel has not come back on but it continues to miss

Did you read out the codes before you cleared them? How old are the plugs and wires? What brand are the plugs?

yes the codes were misfire cylinder 6 something about a fuel relay swaped the relay in the distribution box is there another one

one thing i just thought of is that it started missing after i took a super chips programmer out of it could this have anything to do with it :confused:

Can you answer the other 2 questions?

yes I did thy were p0231, p0306, p01000 . the plugs and wires should be between 30k & 40k

I'd sure try a new plug and wire in #6 at the very least. The P0306 is the clue there. You still haven't identified the brand of plugs, and are they OEM wires or aftermarket, and if aftermarket, what brand?

Not trying to give you a hard time, but you aren't answering the questions. Non-Motorcraft plugs and wires often don't last as long as OEM or can cause problems - just read some threads here to see what kind of luck people are having with Bosch plugs in Ford truck engines..........

You are taking things a bit to simplistic.
The 306 code is a monitor telling you that cylinder is misfiring.
The causes can be a fuel injector, a plug, a wire or a coil pak.

The 231 code is a monitor and command of the fuel pump circuit.
Many places a failure can occurr.

The 1000 code is telling you one or more diagnostic tests have failed to complete and clear all flags. Emmision's testing looks at these for a pass or fail and sticker issueing.
This happens when you clear codes, power down the PCM and when insufficient drive cycles have been made so all tests have a chance to run to completion and when a fault is present that fails the peticular diagnostic during the drive cycles.
Fix the 306 cause then the 231 cause, then the drive cycles will clear the 1000 code after all drive condition have been met.
This is why I stated the first line as I did.
Good luck.

the truck is backfiring when you get in it hard if that helps narrow it down

If the truck is backfiring and you can't figure it out, I would not play around with that kind of problem. You could lose your engine over this. My area that I would look at is a injector problem if you are using the correct plugs.

My first thought on backfire on this engine type is a possible low fuel pressure condition assuming no other faults.
This tends to explain the easy starting and idle but not enough fuel for power.
Test the fuel pressure. It should be found somehwre in the 38 to 40 psi range and not fall with acceleration.
Possible a fuel filter needs changing or water in the gas, fuel pump etc.

Back fire can be the results of very lean conditions making the combustion very quick and very late or early to the point the cylinder can either combust in the intake tract or the exhaust tract before the valve closes.
On this type engine with the ignition so precision, it can't be the results of timing but of fuel conditions or if the cam chain drive were to slip a tooth altering valve timing in relation to the ignition. The cam position sensor would be triggered at the wrong time also.
Just some thoughts..

Check to see that your muffler is not restricting the air flow... I had an old dodge that started missing and I did everything tuneup wise and it still missed came to findout the muffler was no good causing a restricted flow of exaust...