Hey guys! I’m brand new to Ford trucks and just got an used 2004 FX4 with 37K miles and regular cab. Last week I was on the highway at about 50 mph and when I pushed a bit the gas, it started to shake and stumble and had no power (like if it was out of gas). The check engine light came on, then started blinking, then it stopped to remain like that the rest of the way, which of course I kept at about 45 mph since any bit more of the gas will make it stumble (it seems that when I need more power the problem shows). Took it to the dealer where they got two errors: Knock Sensor and a Misfire on cylinder #2. They replaced both sensors and the spark plug along with the coil. Now there are no error codes but still have the problem… they told me that it could be the differential (I have bigger tires but the computer was reprogrammed for their size at the dealer). Next day told me that the differential was OK and they were going to check on the gas pump which it might have a short cut… they used some sort of thing to feed the engine not using the gas on the tank; still have the problem. Dealer is clueless but they are trying to find the problem. So, the question here is if someone knows anything about what could this problem might me related to. Thanks a lot guys.

 

That happened to me last year in my 2005 regular cab. Turned out to be a bad fuel pump. Dealer replaced under warranty; truck has run fine ever since.

 

Could be the differential... Holy S.... First thing you need to do is stay away from that service department. Then try a new fuel filter. From what I've heard these trucks are really sensitive to poor fuel flow from a clogged filter. I think the suggested interval is like 15K miles. 1 tank of crappy gas will cause issues. But seriously, run away from those guys. They will do more damage then good....

 

Thanks a lot guys. Yesterday afternoon I finally got my truck back. It turned out to be a wire harness running from the computer to the inyectors that was grounded... anyway, truck's fine now and I will definitively stay away from the dealers; this problem was found by a mechanic that used to work at the dealers and certainly was much cheaper.