When this started the Navigator just died while my wife was driving at 25 mph and it wouldn't restart! When I got to it found a 30 amp fuse out! Can't remember the fuse number (I think it was 19) but if you are looking at the fuse block under the dash cover and looking at the fuses it is the one on the bottom left that was out! I replaced it (unfortunately had only a 25 amp) it started and on came on the SES (Service Engine Soon) light. Scanned and found the P0306!

OBDII code P0306, I know that it's a misfire in cylinder 6! Replaced coil, spark plug and it comes back! Tried swapping coil, plug and fuel injector with different cylinder and still P0306! Performed compression test and leakdown and both perfect!!! Trying to diagnose backwards and can't figure it out! I don't have a manual on this vehicle and am trying to ascertain the electronics! BTW you can feel the misfire!

So thats my story, has anyone got an idea? Unfortunately had to take it to the $tealer since they were the closest shop, and they don't know yet either, but are trying to say it may be a problem with the head and will have to be replaced, but they sound more like they are guessing at this point! I have a hard time with that when compression and leak down are perfect. Does this beast have a central control module or ???? It sure is striking me as electrical and not mechanical!

Any and all help is greatly appreciated! I've posting this in multiple places on this forum, since being new I am not sure where the best spot to post would be!

Thanks

2000 Navigator, 107k miles

David

 

If we relate the fuse blowing to the dead cylinder, I would suspect a wiring problem with the #6 injector or the #6 little coil wires. One of them may have gotten against the block either by rubbing or a rodent chewing on it. It then burnt in two and blew the fuse, and is now not touching the block, but you get no signal to fire the coil and or the injector.

 

Just got a call after bitching the $tealer out yesterday about it being a short and not mechanical and guess what!

They found a wire to the injector was shorted out! Tried to sell me a complete wiring harness for over $1k installed and I said no, button it up and I'll fix it! A couple minutes later they came back and said oh, we can fix the wire we don't need to replace the harness!

Damn $tealer's, I don't care what I have to do, I'll not go back there again!!!

Thanks guys, I appreciate the help!