Hi I have an 2003 E-250 with the 4.2 engine, it has 180k on the original engine. It had sluggish acceleration and gas knocking as accelerating so I replaced the plugs, wires, coil, and gave it a seafoam treatment. After replacing the plugs I started getting misfire codes on #5 and #6. I pulled the Autolite double plat plugs out and put motorcrafts in all gapped to .054. Still getting misfires. I noticed #5 and #6 plugs were fouled. I then changed the PCV valve and hoses and the EGR valve but still getting errors - now I am geting P1151 and still the misfire codes P0300, P0302, p0305, p0306. Rough idle in drive and reverse - idles fine in park. Any idea why the #5 and #6 are getting fouled and any help on what to try next? Thanks in advance.

 

Sometimes we solve more problems by asking questions.
When you changed the plugs the first time could you have crossed #5 & #6 wires ?
If you didn't have the misfire problem before changing the plugs and now have it, did you put any kind of antiseize on the plug threads ? If so, maybe too much ?
If you pulled on the wires too hard when removing them from the plugs could you have separated the wires internally ?
Is it possible in the process of installing the plugs and tightening them at a bad angle the insulators could have cracked?
Could you have moved the injector plugs and they are not making good contact?
I don't know the answer to your vehicle's problem, but maybe the questions might .

 

Thanks for the help, I have been reading some of the other posts. I think they should rename this forum to Hanky's garage.
To answer your questions:
Yes, I had the misfire in #5 and #6 on the first set of plugs.
Yes, I did put anti-seize on the plugs but I did not put much so I don't think that is the problem. I did not put it on the second set.
I replaced the wires but was very gentile with them after ripping one on removing the first set. I suppose I could check them but I don't believe that to be the problem.
I don't think I cracked any plugs. I tightened them to 11lbs per ft. as per specifications. I have a couple of 2006 F150s 5.4 triton v8s from which I learned about cracked plugs.
Injector plugs? What do you mean?

Is it possible this is caused by the ERG? I was going to plug the vacuum to the ERG and see it the misfires/rough idle stop tomorrow. Maybe it is the EGR sensor or the AIC?

Thanks again.

 

I asked about injector plugs, but if the fuel is getting there to foul the plugs , that would eliminate the possibility of no fuel available to them.
The cyl numbers on the coil wiring looking at the coil from the front of the engine should be,
passenger side, front to rear, 1-2-3
driver's side, front to rear, 5-6-4 Is this what you have ?
Usually if you get gas knocking on acceleration the EGR valve may not be working or the passages could be plugged with carbon, but you don't usually have a loss of power. On the other hand if the EGR was stuck open even partially it would not idle or would idle rough.
I don't remember if you stated whether the vehicle had this problem before changing all those parts. Did it?
Just in case, the cyls are numbered from front to rear with #1 starting on the passenger side then on the driver's side 4,5 &6 front to rear.
You can see how confusing it can be when replacing wires from the coil to the plugs.

 

Well, thank you. Yes I had the #5 and the #6 reversed at the coil. It runs much better now. Thank you!!!