My dad has a 2003 F150 SuperCrew 5.4. It has 80,000miles on it. The truck never goes offroading and is babied a bit. The hardest thing it has done all year was pull a 4000lb trailer accross Nebraska on 2 different occasions and a 7000lb trailer around town. It hasn't had a problem up until today after leaving the state fair and getting on the highway.

He said it drove for a good 20 miles at 70mph and then he noticed he was loosing speed. It settled at around 50mph top speed and was bucking. He found out that by taking it out of overdrive and keeping the revs above 2000 allowed it to have enough power to keep going. In town he says he has to keep on the gas or it will stall. Once home we hooked it up to a scan tool and this is what it found:

1.) P0171 - Bank 1 Lean.
2.) P0174 - Bank 2 Lean.
3.) P1131 - Lack of H02S1 Switches; Bank 1 Sensor 1
4.) P1151 - Lack of H02S1 Switches; Bank 2 Sensor 1
5.) P0136 - 02 Sensor Circuit Malfunction; Bank 1 Sensor 2
6.) P0156 - 02 Sensor Circuit Malfunction; Bank 2 Sensor 2
7.) P0300 - Random/Multiple Cylinder Misfired Detected.

All of this popped up at the same time without any warning, it just suddenly happened. We don't think that all of these sensors could have went out at the same time. So it has to be one part that just failed and is throwing everything off right? Anyone have any ideas or help? Thanks.

 

Has the fuel filter been replaced?

 

No it hasn't. I wondered that earlier but figure if that was the problem this would have slowly developed instead of instantly happening. Fuel filters usually don't get plugged instantly. My dad is a little lazy about services. Nothing has ever been replaced on the truck. All filters, plugs, wires, everything is original. Minus the air and oil filter, which are also somewhat neglected. He is about 3k miles and 4 months overdue for oil service.

Another thing I think we're gonna check is vacuum leaks. I did some google searches and it seems that at least 4 out of 7 of those codes will pop up at the same time if the right tube is leaking. I did a quick inspection by flashlight but didn't find anything. This would also probably go hand in hand with everything spontaneously happening at the same time if a tube suddenly came off on the highway.

 

sounds like the truck went into default mode. Check your fuel filter and mass air sensor

 

It doesn't seem like default or reduced power mode. It has a very rough idle varying between 300-800rpms and jumps back in fourth. It kind of reminds me of a high powered drag cars rough idle and kind of makes the sound too.

I just took it around a second ago to see what it was like. It bucks and shakes horribly at 1500revs on the highway. When you come to a stop, assuming it doesn't die, it has the rough idle and you have go WOT for about 4 seconds or so to go anywhere. In the four seconds the rpms are jumping between 800 and 1200 and it shakes. Then suddenly it flies to 2500rpm burns out and has all the power it normally would.

I disconnected the oxygen sensor so it would go into default in case the sensor was putting out some absurd value. But it made no difference. Still have yet to check fuel filter, will be done tonight.

 

It's fixed. Unbelievably a leaf somehow bypassed the air filter and landed on the O2 sensor. Pretty crazy. Runs great now. We're still servicing it tho.