That baby is the one that makes it difficult to remove passenger valve cover . It goes to the accumulator tank on the passenger back fire wall .then the other side of tank goes into firewall to ac coil .
You should not have any trouble with no 1 or no 2 , I remove computer and bracket to get to 3 and 4 .

 

A buddy of mine has a Tacoma that kept throwing lean codes on one of his banks. I was the friend with the code reader and am a tech type and good troubleshooter. He tried a lot of things on his own but I would help him, especially with the code reader. New O2 sensors didn't help.

Through all my buddy's problems the one surprising thing I learned is that the O2 sensor doesn't have a clue about rich or lean... not a clue about fuel or hydrocarbons. All it knows is the O2 level. That's the ONLY thing it can measure. If you are misfiring then you aren't burning all your O2 like you should... so the sensor says "Hey computer, I'm seeing too much oxygen" so the computer ASSUMES there isn't enough fuel and throws a "lean code". He ended up replacing two COPs before finally curing his CEL problems.

This is only one possible scenario out of many to do with a lean O2 sensor code reading... but it's the one I didn't suspect until it was explained to me what the O2 sensor and computer were actually doing.

As far as what to buy for your Ford: I put all new Motorcraft plugs and a complete set of COPs on my 2V 4.6. last June. Couldn't afford the Motorcraft COPs and heard bad things about the cheapo ones so I compromised on a set of MSD COPs from Amazon. The quality looks fine and the set of 8 was less than $100 if I remember right. They've been fine for 7 months so far... and they are RED!

 

^^^Link to $100 MSD's please.

 

^^^ 'ALMOST' 100% correct on everything, but I feel over emphasis on O2 sampling risks leaving a wrong impression - possibly leading to mis-diagnosis.



Absolutely 100% correct. Just keep in mind how 'FAST' the PCM is sampling and reacting, or you will describe an AVALANCH SCENARIO where the PCM will lengthen fuel trim pulse widths, diluting oxygen content, lengthening pulse width further - until TILT. The PCM is varying injector Pulse Widths longer & shorter about 6 times per second and sampling O2 readings each time. It (not the o2) can figure out pretty quickly that there are misfires. (It's fast enough it even verifies misfires by seeing the change in crankshaft rotation rate to count misfires).


100% correct again, - provided ONLY that the misfire is electrical in nature, and the rate does not exceed that which will shut off fuel to the offending cylinder and report a catalyst damaging condition. Periodic, random 'electrical' based misfires will drive Long Term fuel trims positive on the bank - and CAN result in a lean code.


100% correct, including a vacuum leak 'in reality' leaning mixture too much - or an injector sticking closed (The PCM will lengthen the Fuel Trim attempting to compensate for the lack of fuel from the sticky injector - resulting in a lean code, and the sticking /closed/ injector is actually causing the miss.


There is a lot to think about. Vacuum leaks are fairly easy/inexpensive to eliminate in the diagnosis process. The others pose a greater challenge. Mode 06 test results for misfire counts, and live data Short term & Long Term fuel trim monitoring are at the top of the list for that.

 

F150Torqued -- Thanks for the corroboration on my O2 sensor experience. You are correct in saying that the OP could have any number of causes for his problems. I just wanted to throw out one that surprised the heck out of me.

I was wrong about the MSD coil price. Ooops!
My 2005 2V 4.6L takes MSD part number 82428 and cost me $187 on Amazon. If you have a 2004 with a 3V 5.4 then you need a *different* MSD part number and I see that some of those cost as much as $245. Ouch! That's getting deep into real money.

I don't know if you have a Heritage Edition, 2V or 3V, or what so it's up to you to find the right parts for your truck. Don't take my word for it. Below is a link to the MSD webpage that gives an overview of their Ford COPs. Once you find the correct part number then go to Amazon and put "MSD #82???" into the search field and see what you come up with. Amazon is usually cheaper than buying direct from the maker, for some reason I don't understand. You could also check out prices on Rock Auto. They put a little heart icon next to the parts that they think are the best value/quality.
https://www.rockauto.com

https://www.msdperformance.com/produ...ord_cop_coils/

Good Luck...