Persistent #8 misfire, 01 Navigator

[Fordgirl01]

Items have to be moved aside. Also you'll need a 7mm flex 1/4 inch drive socket to get off/on the bolt that holds down the coil. A sparkplug socket that has locking extensions helps. A hunk of hose that fits snug over new sparkplug to start into threads helps a bit. No one said this is going to be easy! But once you figure it out, it's not that bad the next time you have to change those back 2 on both sides. Lots of videos online to show you how. You can do it!

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I do have the fancy plug socket for that purpose and plenty of other tools. I am very stubborn so I’ll get it if it takes me all summer!! I rarely admit defeat. Thank you for the encouragement[emoji16]


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[1955moose]

If it gets to you, walk away, have a drink, go back at it. Why pay some idiot to screw up your SUV, when you can do it for free. Scrapes on your hands and arms, are battle scars, the more the better the job. Band aids, Neosporin, tape, all part of your tool box. Like lifting weights, no pain, no gain!

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[Fordgirl01]

My thoughts exactly!! That’s why I have more than one vehicle-so I can walk away and finish it later.


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[Fordgirl01]

The lean running codes can be bad catalytic converters. As we've posted here, concentrate on those 2 cylinders for now. #3 is a new code, so you'll want to replace that coil with one next to it, see if miss fire moves. After that I'd get a smoker, and see where the smoke comes out from in the intake. I also like taking old school compression tests of those suspect cylinders. If you've got a bad valve or 2, you can be chasing your miss till Christmas. After you get a handle on the miss, run it by an exaust shop and let them check the back pressure of the 4 cats. Are you doing the work yourself? Report what you find, we'll get you through it.

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OK-I am finally getting after the 01 Navigator. I pulled the coils out (5,6,7,8). No sign of dielectric grease-isn’t that standard practice? I’ve always seen evidence of it when I pull out a coil. Maybe it’s standard dealer practice not to bother!!

So, the #8 plug looks crappy. I haven’t got #5 out yet (I decided to pull them all to see if it even looked like the dealer changed what they said they did-2 out of 4 coils are either different brands or just have he gray boots instead of black, but they all seem new). I’m waiting for #5 to soak for a bit (and charging my work light). It’s in there really tight.

I plan to do a compression test on #8. Hopefully I can-that spot is a real PIA!!

I will update later.



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[Fordgirl01]

Can I do the compression test with the coils out as long as the other 3 plugs are back in? I also have some evap hoses off-I assume that doesn’t matter for the test?


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[Fordgirl01]

I got plug #5 out-it was tight enough I thought I broke it when it let go. Luckily it wasn’t broken.

I was able to get the compression tester threaded into #8 without too much trouble.
Compression test attempt.... I looked up ignition fuse and pulled #111. It started so I panicked, immediately shut it off, watched some YouTube videos and looked at my fuse diagram again. I see there is another ignition fuse so I also pulled 113. The videos I watched said disable fuel pump by pulling fuse, so I pulled fuse 10 for the fuel pump. Now it won’t even turn over I assume because of the ignition fuses being out.

Do I just have to remove the fuel pump fuse and put the ignition fuses back in to do the compression test??


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[Atman246]

The other way would be to unplug all of the coils,and remove the fuel pump fuse. No fuel and no spark,no start. Good luck,you're doing awesome.

 

[Adieu]

Swap an injector to #8 and see if the problem moves cylinders (I assume you have a code reader? If not, spend 12 bucks on Amazon for an elm327... Panlong brand works well and last)

If somebody DID give the engine bay a bath, drowning an injector along with a coil is pretty typical

 

[1955moose]

Easiest way to be sure it won't start is pull the plug going to the crank position sensor up front. Yeah the Moose is back, well for now.

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[TobyU]

No big deal if it starts especially if only one plug out. You cold run it all day if you wanted.It just puff puff puffs fairly loudly.
However you can kill fuel or injector pulse and get it to still crank. Could pull FP reay as I thing an 01 has a removable one, or injector or fp fuse/fuses. Some ecm/pcm fuses will let it still crank.

A proper compression test is actually done on warm engine (usually) with all the plugs out and with throttle at WOT (wide open).
Not that dealers even have or know how to use a compression tester anymore. They do a computer cylinder balance test.

I would swap that coil on 8 for one of the new ones you have in it or at least to the easiest spot to get too. It is probably misfiring at least some. Or go buy a single new one at parts store with lifetime warranty....about 35-45.00.
I have been using the ebay sets for under 40 for all 8 and had nothing but great results with them. Earliest I had any fail and they were only occasionally misfiring was over 7 years.