As you know the codes 301 and 306 are specific cylinders as a 'miss fire'.
Revisit the boots and plugs.
Make sure the boots are not enlarged on the tips such that a poor seal is the result.
Use grease inside the boot tips to be sure the tip of the boots has the best chance of finding the plug and slips on without hangup since you can't see this when installing the boot/cop assembly.
Another tip that might be of help is to install 2 greased #110 O rings on the plug insulator pushed all the way to the plug shell. They won't interfere with the plug socket for tighening. If there is water intrusion at the top of the boot, try a #10 O ring in the top grove well greased and carefully installed with a small twisting motion.
The plug rings will take up the room between the boot and the plug body and help seal against moisture. Worth a try for a few cents and some effort.
Last, no trick plugs, only the standard single electrode types.
And be sure you have eliminated the coils as a source of problems but do not swap locations. This method can cause the loss of good coils at the defective cylinders and cost $ and aggravation until all is caught up with. I know many do it but not a good practice.

 

Thanks again! Plugs are Autolite Double Platinum. Same ones I ran previously. Checked and rechecked. Good idea with the o-rings. I did notice some swelling on the boots, so I'll give it a shot tomorrow. I have swapped coils around as a method of testing. I have also disconnected them as well as injectors while running to see if I can pinpoint anything. Is it possible to damage them this way? Is there a preferred method of testing the coils?

 

ok guys.. i read through all of this thread, and i don't remember seeing anywhere in here to actually take a node and check the fuel injectors. Tell you guys why i say this:
I had a 2000 F150 with a 4.6L that was doing the same thing. But mine was a #5 and #6 misfire. Tried several different things, and got some weird codes. After taking a fuel injector node and checking the injectors for those cyl., what i found was 2 broken wires inside the harness that goes back to the PCM. What i found was that when the truck was assembled, the harness tray at the rear of the engine did not have anything on it to hold the harness to it. It eventually rubbed a hole in the harness and shorted the wires to ground. this finally caused the wires to break. But i would definately get an injector node and check to make sure the PCM is switching ground like it is supposed to. Good Luck!

 

That's a "NOID", not a "node"... If you ask for a node, the parts/tool guy will give you THAT look...

A open wire to an injector should set a fault code...surprised you didn't report any fault codes.

There's no such thing as a "power valve".......

If you have indeed eliminated both ignition and injectors as the fault (I'm not certain you have), it's time to look at the base engine. A compression check, especially on #1, sounds like it is in order.

Steve

 

Well thank you for correcting me on that Steve. Yes, it did have several codes, and I fought with it until I found the root cause. IF you want to see the entire thread on this, feel free to check it out for yourself. All i was doing was passing on what i hoped would be helpful imformation. But the link to my thread on this is as follows:

https://www.ford-trucks.com/forums/5...6-misfire.html

give it a look and hopefully this will help you bigdaddy. I just don't want anyone else to have to go through what I did until I actaully found the issue with my truck.

 

Thanks Guys for chiming in -This place is better than any book I've seen. Firebug - Your thread is a familiar sight, seen it several times since this happened. Is the noid light a dealer item? Previous testing was done with a stethescope and all were clicking. This morning I took each injector out, put power and 40 lbs of air/solvent through each one, spray looked good. I know this might sound like a dumb way of testing but it seemed like a reasonable thing to do at 5:30 am. ProjectSHO89- does this eliminate injectors? Also, if an open wire set a fault code, would it be any of the codes I've already gotten? I'm trying to locate some coil boots now and try that next. Then I'll run a compression test (as soon as my neighbor returns it). Thanks again!

 

Baddaddy, I bought them from advanced auto parts for $20.00. The set included 6 of them, basically for any vehicle. My truck did in fact throw several codes, all of which indicated a cyl. misfire. If I can help you anymore, just let me know. Good luck.

 

what did you buy for $20?
six what?

 

I bought a pack of noids to check the circuits for the fuel injectors. Small price to pay for a valuable tool.

 

Hi guys have had this same problem I also have a 2001 super crew 5.4L when I had this problem I ended up replacing the fuel injectors on the clinders that were misfireing this took care of the problem

 

Hey Guys - Its been awhile, had to drop this project to take care of some other things. Finally did a compression check - 0 lbs on cylinder #1, wet and dry. All others including #6 were good. Pulled the valve cover and visually checked cam and valve operation - looked normal. Plan is to button it back up and get it indoors to pull the head. Before I do that, are there any other checks or tests I can do, maybe valve lash adjusters? Seems I read something about those on here, but can't find the post.