2004 Ford f150 FX4 5.4 (Engine long block is brand new) I am running new Autolite HT0 plugs as I have a Roush Supercharger.

I have read most of the threads regarding this code but I have a few questions:

1) I was getting a misfire and a few COP type codes P0351 etc..I changed 2 cops even though these were new within the last year (all 8 were new). The FPDM was old but not completely rotted so I replaced it with one with 60K miles from my 2008 F150 just to test it. I bought a new one for the 2008.
The Misfire codes cleared but I am still getting misfire "feeling" and now a new P0171 Lean bank 1 code. I checked for vacuum leaks and found none.

Could the newer 2008 FPDM be sending a different signal that a 2004 can't recognize thus causing the lean codes? I noticed the male electrical plug on the 2008 is different from the 2004. In fact the new FPDM I bought and installed on the 2008 will not fit the "plug" from the 2004. The part number for the 2008 is 5L8A-9D370-AA and it "crosses" with the 2004 FPDM part number 4L3Z9D370A basically telling me they are same. However the Electrical connections, although the same size have different pins inside.

Bottom line could a good FPDM from a 2008 that worked fine in my 2008 be bad in 2004 and send a lean code and cause a "hesitation type misfire".

I have a wide band A/F gauge and the truck randomly shows lean readings under various throttle demands. I mean it will go from 15 to 22 and hover on 22 and then back in line to 15 It stumbles and hesitates a bit.

I have cleaned the MAF, cleaned the Throttle Body, check the injectors (only by unplugging them one at a time), and checked the COPS the same way. The Injectors are 39 pound Roush Kit injectors but have at least 30K miles on them.

Advice will be taken. Thanks!

 

The Rock Auto catalog shows the same FPDM for 2004 and 2008, both Dorman and Airtex-Wells.

 

Thanks GLC. I got my new Dorman FPDM from Rock Auto for the 2008, and it works fine in the 08 but it won't fit the 2004 due to the electrical connection. It is a bit weird. That's what made me wonder if the PCM may get different signals from them in 2008 than 2004?

Jeff

 

I put the Dorman FPDM from RockAuto on my 2004 without any problems.

 

Took off supercharger today and installed new HT0 Plugs gapped at .030. Re-greased COPS (These were new 5000 miles ago and 2 of them are brand new again...). Cleaned my 39 lb fuel injectors (Again). Installed a strip of Gasket maker under the supercharger on top of the aluminum gasket that Roush provides.

Not going to fire it up until Thursday. I am out of options. There is nothing unhooked, nothing broken or leaking, the plugs I pulled out had 2400 miles on them and looked perfect but I will admit I think the HT0 plugs suck. The problem is nobody makes a cooler heat range plug for supercharger applications that is worth a ****. This misfire thing has gotten bad (complete with overdrive shudder). I cleaned the MAF and the TB again (they already looked fine). The fuel filter has 5K miles on it, I replaced the FPDM and the Fuel rail pressure sensor. I suppose it could be a fuel pump but these trucks misfire their *** off and I don't want to replace the pump just to replace it. I also checked the wiring harness under the driver's side door and it was fine. I got a bank 2 lean code (P0174)too recently and an o2 sensor locked in lean position code (P2195) bank 1. I cleared the codes after doing all the work today and try again Thursday.

Any ideas?

 

It could be a clogged or inoperative injector on bank 1. If that happened one cylinder would be pumping only air or a lean mixture into the exhaust and you would read a lean condition on that bank.

 

I agree but I thought I would get an injector code? I cleaned them 2 days ago and put everything back together today. I will test it tomorrow after the liquid gasket sets up underneath the Roush Charger.