I,m very new to this. 2003 f150 screw 4.6 no power, misses, valve clanging on acceleration. Codes read are p0174, p0172, cyl 1 and 2 misfire. Things recently done are new plugs, new set coil pks, new oem maf, new air filter.
Still runs very poorly. Just wondering how one side can be rich and the other lean. It seems that after reading some of the other problems in the forums that I have a lot of checking to do. Thanks in advance for any advise!

 

The only time I've ever seen that is when the upstream O2 sensors were swapped, the bank 1 sensor is connected to the bank 2 connector, and vice versa.

 

What misfire codes did you get ? 301 & 302 ? BTW - You don't have coil packs on an 03 4.6L . It's a Coil Over Plug (COP) system - very different form a coil pack system.

Sounds to me like the motor got wet at some point and a few coils got toasted. That's a common problem. If you didn't use Motorcraft plugs when you changed them - that can be part of the problem. This model doesn't like Autolite plugs.

Also - your reading Rich on Bank one because your dumping raw fuel into the cylinders that aren't firing. Take care of your misfiring issues first and that code will disappear.

The lean problem could have something to do with the misfiring problem as well. Replace the coils on 1 & 2 - get all 8 cylinders firing and go from there.


Best place for coils is here -

http://search.stores.ebay.com/GLOBAL...271212QQsofpZ0

Replace the whole set and use Motorcraft (ONLY) plugs is what I would do in your situation.

Good Luck

 

I thought they were swappable Quintin ? Isn't the harness just wired differently in the rear ? In earlier models maybe ? I know they have two different Bosch part numbers, but mann , they look identical and the sensors themselves are wired the same - on my 98 model anyway . I never swapped them personally - just thought I had the option.

I did try Borg/Warner sensors once in both forwards and got 9 mpg - Went back to factory Bosch sensors and was back up to 16 mpg on average. I was surprised how much difference that made.

 

P0301 and p0302, motorcraft plugs, 8 new (COP). Will start running down vac leaks, have fuel system checked, Check on those o2 wires - Thank you!

 

Yea, make sure your wiring harness isn't to close to your AC accumulator - that can freak out the ignition system. This is a strange problem. I didn't catch that you changed the coils already. Seeing that you have and also have Motorcraft plugs in there, you are still receiving misfire/rich codes ? I was going to suggest a fuel filter being 1 & 2 are the furthest from the pump, but , yea, this problem isn't making much sense unless you have a harness problem - something in the wiring or like Quintin suggested . Quintin's a tech , definitely trust that information.

Strange problem - Good Luck with it.

Just a thought - If she was missing on 1 & 2 before you changed the plugs and coils and the same problem after it would almost HAVE to be a wiring problem or an internal one. A compression check on 1 & 2 would be in order. Check to make sure your receiving proper volts to both connectors on the harness as well. It's not a vacuum leak, not in this case.

 

I have seen fuel trims like that when the motor was out of time by a tooth, pinged real hard on acceleration too....just something to keep in mind,

As Jbrew said as well, a compression check or hooking up a vacuum gauge may be in order to track this down would give an indication to any internal problems.

How many miles are you at, maybe a little more history of what happened?


Also I remember we had a few 4.6's come in before that had spit the rockers out on the valve, can't remember if they were intake or exhaust, however the result would probably be the same....

 

I know this is an old post but hoping someone has figured something out. 03 expedition 5.4 original codes p0300 p0301 p0305 p0171 p0175 got misfires taken care of still reading bank 1 lean bank 2 rich. Clean maf sensor replaced tps fuel filter and still runs like garbage. Stutters chugs lifter knoch at times and just stalled at stop. Anyone have any ideas?