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!

Thanks

2000 Navigator

David!

 

Did you erase the code after you swapped the COP & before you started the vehicle?

 

Unfortunately it is at the $tealer and they are the ones coming back with the continued misfire! I would assume that they are smart enough to clear the code! But I can't be sure!

Thanks

 

Never ***-u-me anything.

 

I hear ya! that's why I had to answer the way I did!

 

I looked up the fuse that you replaced on Alldata. The fuse is for the "throttle position output to pcm." You may have a bad throttle positioning sensor or the wire harness may have a broken wire in it. Something made the fuse blow.

 

Thanks for the information! I agree, something with the electrical system caused the issue and continues to be the issue! With all the details, I have a very hard time believing that the mechanical aspect of the head could our would cause this problem!

I did mention that to the $tealer when they called me yesterday to advise that head replacement is over $5k an would just suggest a long block for over $8k! They are supposed to be tracing that down but I haven't heard back yet! If they don't have a valid repair plan this morning, I'm having them reinstall the original bad coil and I'll bring it home and start tracing everything by hand!

Thanks again and if you think of anything else, please let me know!

 

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!